Homemade rigidizer?

[Frosty]

Mark: You're making some common beginner's mistakes: Forget what you see on Youtube. There are I don't know how many ways to make a refractory that doesn't work very well. The video how to in your last post is a perfect example of putting WAY too much work into a simple piece of equipment that isn't going to work well for very long. You're also combining ideas and methods from several different "experts" with a camera and ISP connection.

Metrikote is NOT a rigidizer or refractory. It is a kiln wash. Putting it ANYWHERE but the fire contact surfaces IN the furnace is a waste of money and time. 

Sodium silicate is a popular internet expert material and it WILL stick stuff together but it melts at a lower temperature than a decent forge's every day operating temperature. Using sodium silicate as the binder means using a 2,000 f. material to build a 2,600 f. piece of equipment. Colloidal silica rigidizers won't take much more than sodium silicate but it doesn't break down at high temps. it melts.

Rigidizers MUST be shielded from the flame face, they WILL NOT take forge temperatures no matter what someone on the web says. Nor will perlite.

Prepare your ceramic blanket refractory OUTER liner. I use the name Kaowool only because it's what I have available and I'm too lazy to remember any of the other brands. Some things are standard though, 1" 8 lb. is preferable and is commonly a 2,300 f. refractory blanket. And NO, Kaowool is NOT appropriate for the contact surface unless you're going to be running your forge at high orange and below. The ceramic blanket MUST be shielded from the flame. It will compress and covering it with a brittle substance like castable hard refractory endangers the refractory. If you bump the forge too hard and the blanket compresses under the hard liner the liner will break up. That is why we rigidize the blanket, ONLY the blanket. You don't thicken it you WANT it to flow into the blanket's fibers and dry. Firing it fuses the silica with the fibers making the blanket stiffer.

Sodium silicate falls under HAZ MAT. rules and requires PPE to use safely. Colloidal silica only requires a good dust mask bug eye goggles and a cool shower. Hot water opens your pores before it can rinse the almost molecule fine silica off your hide. This is the reason emergency showers are all cold water. The stuff is listed as an irritant and otherwise has a pretty clean MSDS.

It's inexpensive, carries no HAZ MAT restrictions and works a treat. Just mix it with clean water and spritz it on. Spritz the blanket with clean water first to butter it, this will allow the colloidal silica rigidizer to penetrate more deeply. This is a GOOD THING.

That's rigidizing, no magic, no secrets it's been standard practice since before ceramic blanket refractories were invented.

Use 2 layers of 1" 8 lb. Kaowool. Place them in the forge shell cut slightly oversize so it holds itself in position by compression. Rigidize it and let it dry. Fire cure the outside layer now, a Bernzomatic torch will do the job nicely, just bring it up to red heat, that's plenty. 

Cut and lay the next layer of Kaowool. Butter and spritz the first layer's inside surface and the surface of layer 2 that will contact it with rigidizer. This isn't a  must but it does provide a better bond, it's a "can't hurt, might help" thing. Once layer 2 is place butter and rigidize it. Let it dry and flame cure it.

Press the liner with your finger, it shouldn't compress without pressing hard. If it does compress butter and rigidize it again. 

Once the insulating outer liner (Kaowool) is dry and flame cured, cut your burner port(s). I use a sacrificial hole saw, don't hog it and it won't tear the rigidized Kaowool. Drill it over sized so you can plaster it with the flame face refractory. 

Once you have all the mechanical mods made it's ready to lay in the hard refractory flame face. Recently "Kast-O-Lite-30 hi." has become the popular consensus "best stuff." It's a castable, 3,000 f. high alumina, bubble refractory. It is concrete hard at it's top operating temp 3,000 f.

High alumina refractories are not subject to being dissolved by borax containing refractories like we use during forge welding.

Mix the refractory with only enough water to make it workable, butter the kaowool and plaster it approx 1/2" thick with the hard refractory. It isn't going to want to stay in place hanging from the roof. However Kast-O-Lite sticks to itself well, heck the stuff sticks to anything meaning there is NO problem plastering one half letting it set and cure then roll it over and do the other half.

However, if you wish to make a mold and cast it between the insulation and the flame face it's okay, just a PITA. The stuff may look like wet low slump concrete but the aggregate is crushed so it doesn't flow well. Commercially it's troweled or gunned. (sprayed) The wetter you  mix it the weaker it is when cured. It's still darned strong stuff.

Once the inner liner is set and cured. Kast-O-Lite cures like concrete, it does NOT dry, it hydrates and cures. Once set the recommendation is to keep it at 100% humidity between 70 f. - 120 f. I just wrap my castings in a wet towel and give it over night to finish setting and do some curing.

The stuff will cut you a LOT of slack though you can get away without the "proper" curing time, just sitting over night will work for our purposes. I HOPE I don't have to tell you not to let it freeze!

Kast-O-Lite as it is doesn't need a kiln wash to protect it from abrasion and chemical erosion, it isn't susceptible to caustics like borax so there's not need to protect it. However an IR re-radiating kiln wash WILL increase efficiency. Butter it and paint on the Metrikote. Let it dry and flame cure it. Mount your burners bring it to red heat, let it cool.

It's ready to go to work. 

I know I started off with a list of beginner's mistakes but left off one of the biggest. Trying to understand all this stuff will only make you crazy. We see guys spending months trying to find the "BEST" . . . whatever. Unless you know and have experience with the craft you won't know the "BEST" if it falls on your foot. Honest best is a very personal and subjective thing. What's best for me isn't worth doodly to many other guys but the way they do it is just silly. 

You really need some time at the anvil before you can sift the good Youtubes from the idiot junk. Especially building smithing equipment, Youtube forge builds in particular are bad and often just plain dangerous. Not all of them but the vast majority.

And yeah, I've built a forge or 20.

Frosty The Lucky.

 

[BeaverNZ]

Frosty

Thankyou very much for compressing all that great info into one area there are several things that you have enlightened me in that I have been trying to find about ridgidiser use and when to cut the burner ports now i have some specifics I will finish my gas bottle forge.  Cheers Beaver

[Mark Thomas]

On 11/9/2017 at 12:23 PM, Jasent said:

I'm talking about metrikote as a rigidizer. 

Agreed.. I think Matrikote or Matrikote 90 would make a good rigidizer and IR for a Blanket if applied directly to the blanket.
I think the internet may misspell the product. I can't find that spelling anywhere, but, can find Matrikote.

I think I would make two mixes. A thin to soak in, and then a second thicker one to firm it up. ..
It seems to do fine as the only thing you need to use on a blanket.

No.. It won't work on top of a Refractory. It is for blankets..
And, It would be a moot point to cover anything IR with anything not IR..

Not sure if I said something to make you mistake that.. Sorry if I did.

[Mark Thomas]

Nice Post Frosty.. Very informative..
It's what this thread needed..

Just a few notes to consider..
Metrikote/Matrikote: I believe it to be the same product.. The only place I have seen it spelled with an "E", or someone referring to or asking about his product.
If that is the case, then, agreed, it was not originally designed as a Rigidizer, but works great as one..
Same thing as Zircoat W. It's use is coating a mould just before you pour the molten metal over it, but, works great on Fiber Blankets and in a furnace that regularly melts Cast Iron, holds up for years.. Paint it on and Fire Cure it. But, don't ask the manufacturer if it will work for fiber blankets,,, they have 2 other products for that you need to add to your order..
Zircon W can be used on Refractory , sand, fiber blankets, etc.. (verified). I believe is also IR.

According to this page, which has the video I posted before showing the fiber blanket vs the Matrikote coated blanket is on the same page..
link removed
It says, can be used on Fiber Blanket, but not to be used on Refractory..
Were you aware of that, and people are using it over Refractory,  and it is staying on there?  (If so, then, Crazy to read it is..! Ha.)
I guess would be the same as Zircon W if you asked if it would work as a Rigidizer..

Wouldn't it be nice to have 4 or 5 who like to experiment, live a couple of miles away from a distributor who would put all of their extras, broken bags, etc.. aside for testing..Ha.. Nice..
 
I think IR is more important than Insulation in a forge (not melting furnace)..  The ends of a forge, or at least one end is usually wide open anyway..
That is one of the things that I like about my "It won't work" hard brick (No insulation factor) forge still working the same after 4 years..
It heats up quick, and if I want to forge weld, just crank up the propane a bit and forge weld.
It really doesn't get that hot on the outside anyway, and I don't know who would insulate a forge to keep from getting burned by it.
A furnace however, yes, extra layers, extra insulation, etc.. to save money on running it makes perfect sense.

I can't find any distributor  of products like this, or forge/furnace company anywhere close to me.. 3 hours away is the closet.
The stuff I would really like to buy is 6 hours away.. Grrr.. 
And building two units, the idea was, buy larger and use both and kill two birds with one stone..

I have 50lbs of high Alumina (Aluminum Oxide sand blast abrasive) that I ordered and finished the project before it arrived..
Most commercial Refractories use this in their high temp refractories, but, use it  in a finer grade..

The guy in the video uses 2lbs of Aluminum Oxide (Alumina) and 150ml or Sodium Silicate as a binder for his hotface..
Will the binder (which is 22% silica fail before binding the 88% Aluminum oxide(Alumina) ?),, I'm not sure exactly how that works, but, I don't think so..
Kast O Lite is a 35% Silica mix with 55% alumina..

link removed
Not sure.. One has more of the Higher temp and less of the lower temp, but, silica (I forget the term) fuses for a better word over/to the aggregate.

Either way, Fiber or Refractory or both, I'l have the Sodium Silicate, or Sodium Silicate with glass spheres (colloidal Silica) with slightly different ph's, for the project and will mix some up and put it on some fiber blanket scraps I have to put in the bottom of the forge.. In fact, if there is any forge welding going on, I'll do it on top of it for testing it and keep notes..
I only forge weld for Authenticity, otherwise, I either Arc/Mig or Tig it, so will pay close attention.. Usually when I do, it is during production, so,  should get a workout.

All of the Caustic/Acid/flux resistant products I have seen have had an acid (phosphoric acid base) up to this point in my reading.. I don't see any of those products in Kast O Lite.
If it's just alumina, then, the hotface on youtube should do well on both accounts. 
link removed

And, I'll make a small flat brick or two and swap it out with the slivers of firebrick I keep in the forge to set pieces on to make them easier to pickup with tongs, etc..
I'll make some with Perlite and some with Crushed Perlite too, just to see how it holds up.. If it fails, it will go to the do not use list, if it lasts, it will go to the todo list again..
They make "High Temp Adhesives" with Crushed Perlite and Crushed Vermiculite mixed with Sodium Silicate.. I failed twice to find an adhesive made with those products, to find the temperature ratings.. You would think it would be in the 2000 degree neighborhood, but that is not always how it works as I have seen so far..
Anyway.. Lots to learn. And, it's not easy, when the manufacturer says it won't and it will. Ha..

I'll get around to this in a few weeks.
BTW.. Spend some time on the Anvil?? Ok.. Here are some pics of one I spent some time on.. Still using it today. Still looks just as good.
I graduated from Leaves and hooks a while back..

[Jasent]

7 hours ago, Mark Thomas said:

Agreed.. I think Matrikote or Matrikote 90 would make a good rigidizer and IR for a Blanket if applied directly to the blanket.
 

Your misunderstanding me. I disagree that metrikote  would make a good rigidizer.  It makes a good refactory wash.

Fumed silica and water makes a GREAT rigidizer. It is super cheap and simple.  Why re-invent the wheel?

[Frosty]

Mark: would you mind putting our general location in your header? I'm not aware of a number of things you're talking about. Phosphoric acid based forge welding fluxes for instance. Everything commercial I know of is anhydrous borax and boric acid.

Metrikote is NOT intended to be applied more thickly than a heavy coat of paint or it most certainly will flake. It is a kiln WASH, nor a refractory liner material.

Frosty The Lucky.

[Mark Thomas]

On 11/11/2017 at 7:54 AM, Jasent said:

Your misunderstanding me. I disagree that metrikote  would make a good rigidizer.  It makes a good refactory wash.

Fumed silica and water makes a GREAT rigidizer. It is super cheap and simple.  Why re-invent the wheel?

Sorry Jasent.. I misunderstood...
I agree that Colloidal Silica / Fumed Silica and water makes a good rigidizer.. 
I also agree that Matrikote is designed to be a Refractory wash, same as Zircon W is designed to be a mould coating just before the moulten steel is poured onto it.

Just saying, they both work well for Rigidizing the blanket, and the also both work as IR products..
I have not looked at the MSDS to see what "reflective product" is in it, but,  that is what it is sold for, (Reflective Blanket Rigidizer) from this page:
link removed
It is also where it states it is not to be used over refractory, but, used on a blanket...
This 9 Second video shows Matrikote after installing it on a piece of blanket.. You be the judge as far as whether it (Worked or Not) in that capacity..
My vote would be a Yes..
https://www.youtube.com/watch?v=vsi32OIXo7c
Looking at the video, what other properties is it missing for a (Dual Purpose, one application product for both rigidizing and IR on a blanket?)
If that does not appear to be good rigidizing properties,,  what else am I looking for?

I have not yet rigidized a piece of blanket, so, I am only imagining what it "Should" be like.. Seems like I would be happy with the sample in the picture..
Would love to have that particular sample to put a torch on and see if the other side gets hot..

 

[Jasent]

Making the outside hard or even 1/4" penatration isn't going to help much in my opinion. Reasoning for rigidizer is to stop or greatly slow shrinkage and to give a firm base for refactory without inhibiting insulative property's. With out trying it my self and with my limited expirence with matreikote is that it would not penatrate the blanket enough and if it did would take up some of the air voids that are the insulative property's. When I bought matreikote it was $20 for enough to mix one pint. Even if you  watered it down to one gal that's more than double the cost of making colloidal silica rigidizer. 

 

When you you rigidize with colloidal silica and cure it. The blanket gets hard like a dried out sponge all the way threw. Not just a hard shell. The silica coats each fiber taking up almost no air voids at all. 

I see where your thoughts are coming from but like you said with out inspecting and testing the blanket in the video I'm very sceptical.  

I'll stick to proven results I've seen with my own eyes. 

Prove me wrong, seriously.  It   Would be a huge service to the gas forge community to find a better rigidizer that's cost effective! If it works better the extra cost could be worth it.  I just don't see it being matreikote/ metrikote  what ever it's called lol. 

Personally im happy with the results I've gotten with colloidal silica and so I'm not willing to spend time experimenting with finding a better alternative.  Too many other lesions for me to learn

[Mark Thomas]

On 11/11/2017 at 8:39 PM, Frosty said:

Mark: would you mind putting our general location in your header? I'm not aware of a number of things you're talking about.

Ha.. As many times as I have read you guys asking people to put their location, I was sure I had mine, but, didn't look after posting..
Bryson City, NC.. I have it updated now.

Phosphate/Phosphoric: I found this site which is what I go to when I see something new I want to look at in more detail.. It has lots of competing products..
We are all looking for something that will last.. When I see a product that says "Caustic/Acid/Flux/alkali attack/Slag Resistant", up until just now, has had a phosphate base on this page.. Out of the 5 products, one of them says specifically "Super Hybond: phosphorous free for applications where phosphorous contamination is critical".
From what I understand about these products, they are acid bases themselves, therefore resist the Caustic/acid materials in fluxes, etc... I think also what makes a good flux is the acidic base, which actually reduces the melting point of the metals they are fluxing, which makes them good candidates for fluxing..
These are all listed under "Plastics" on this page.. All designed for Patching refractories (lasting patches with good adherence). Also appears that all of the products are designed for direct contact with molten metal.. I have read a couple of times that the worst part of damage to forges/furnaces is the thermic cycling. Heating/cooling, and worse, heating/cooling rapidly.. I would consider slopping hot molten metal onto these products as a worse case scenario, so, seems like some good products to look at...
In some of my other notes,, I was looking at a product that you actually mix Phosphoric acid with the powder (Thermosetting), to cure the product overnight. Creates it's own heat for the setting of the materials.. It was also a high flux resistant product.. Like I said. I did a whole lot of reading in a short period of time without any kind of Chemistry background, so, I was looking for Concept and groups and base ideas as things started to gel in my brain, to later use those things to refine my knowledge.. So, saying that. I possibly could have misses some things.. That's why I always try to post references to what I am describing.. In case I have missed something.
Here are the 5 products on that page that seem to be targeting what we would like to use on the floors of a forge that would be used for a lot of forge welding.
link removed

"Metrikote is NOT intended to be applied more thickly than a heavy coat of paint or it most certainly will flake. It is a kiln WASH, nor a refractory liner material."
I would imagine you are correct.. It does seem to be like the Zircon W in this capacity.. The thickness of paint, so, not designed for thick coatings.. How much of it is actually necessary to do it's job? That is the real question here I think.. Will a thin coat of paint, soaked into a fiber blanket be rigid enough?
Referring back to the 9 second cured Matrikote video: https://www.youtube.com/watch?v=vsi32OIXo7c , it does appear to be "Thick Enough to make the Blanket Rigid",, and it is Marketed as a IR product, which means reflecting the heat from it's surface.. Like I said. I have never used the product.. Only reading about it.
How thick does a IR coating need to be, to protect the substrate behind it (Rigidized Fiber Blanket)?
How much insulating value does an IR product have, if it reflects heat back and away from it? Is 1/8" or 1/4" thick of a Reflective coat the same as 1" of Blanket which does not reflect heat? I don't have the answers to these things, and have not yet purchased a swath of products for testing... But, it seems to me that a paint thick soaked in coating of IR reflective material may be all that is needed for "Forge Walls/Ceilings", if the user of the forge didn't swing their tongs around slapping the walls to see if the coating would break or chip off...
As far as Thermic cycling, would it hold up to the heating/cooling? I know that Zircon W will.. Luckygen1001 is proof enough for that.. It is the product he has been using for years..
What does Matrikote have in it? I have not looked at the MSDS sheet yet. Not sure.. Or, don't remember.. Ha..
Ok.. So, I admit it.. I hate saying that I don't know.. So, I just looked for the MSDS Sheets for both Matrikote and Metrikote..
Still can't find anything on Metrikote, but, Matrikote has several products and names.. link removed

Ahh.. Interesting... Calcined Fireclay, Silica, Alumina, (that pesky Phosphoric Acid), etc..
So, I would be willing to bet that it would also hold up well to fluxes, etc???
In that case,, I am beginning to doubt the warning here: link removed  that says it is only to be used on a fiber blanket and not on refractory.. But, I guess it all depends on how much of the acid it has in it, etc.. So, would have to test to see if it would hold up applied over refractory.

That is kind of the whole purpose to opening up this old post.. It had the most amount of information on it, and it just stopped after some suggestions that we might be onto something else better.. Considering the two biggest problems we have: Finding the right product (not having to buy 55lbs when we only need 5lbs), and not being able to test products that seem to work better than what we are using, because of that...
The other problem we face,, or let me say, problem I ran into.. Was, opting on the side of caution, and using a premixed refractory, and followed the directions to the "T", to get it right the first time and had what I consider a complete failure (Blistering/cracking), when I could have used something completely different and had lasting and immediate results..
I figured after hearing all of the fails using this and that, I would do something quick and easy, and short life and see if it would work anyway when I built my little Lowes Hard Brick forge.. It said 1800 degree brick, but, I think it was 3000 degree brick now, and putting some refractory over the face of it..
I could have built it in the same amount of time or less and used ceramic blanket and Zircon W and been using it the same time I built it.. Fire Cure..
I think it would be well worth someone's time to look at these two videos, and take quick scan of the videos on this channel just to see how much work goes through these furnaces..
And, possibly read some of the comments... I'll say what I know about what he is using.
The Product he calls:
Gannister: Fireclay and coarse Silica Sand.. (Mixed and rammed)
Zircon W: A coating used to coat sand molds just before pouring molten metal in them.. (Painted on with a brush then set with a torch)
Fiber Blanket we all know about..
J-Coat: Similar to Zircon W. He uses the last of his container in the "Rebuild video"..
Waste Oil Furnace Overhaul. (This furnace is 5 years old when it got rebuilt).
https://www.youtube.com/watch?v=MgsU5EibFbA 10 minute video
A fresh build of a propane furnace:  (built one for a friend to use) (3+ minute video)
https://www.youtube.com/watch?v=1DyeESQpac0 
What I really like about both of them is the fact that you can build it and go right to work with it, and it doesn't blister/peel/crack..
Seems like we would see more people using this same recipe, since lots and lots of people are just looking for something that works to copy..
Remember.. Zircon W is a coating used to put on molds before pouring molten metal on them..
It is a reflective coating that some are using mixed with Kaolin clay to do the same right here on this forum, but, with less than lasting results, but, satisfactory for at least one person willing to recoat it from time to time, but another who doesn't care to use it for the same reason..
I am on a different project at the moment, so, don't have all of my notes open, but, there is a replacement for this Zircon W that seems to be hard to find now, that does the same job for the same smelting factory, but, when you ask the supplier about using it for that purpose, he has something else that works better, but, not reflective and requires another product..
Goes back to saying.. They said the same thing about Zircon W, and it works great too..
If it provided enough IR properties to reflect the heat, would it not be sufficient to protect the blanket?
In the first video, if you look at the condition of the inside of the forge, it really does not look like a 5 year old unit.. The wear and tear is on the top.. Wonder if he would have stopped the Gannister 2 inches up and covered it with ceramic fiber blanket and zircon W, if the top would not look like the inside of the forge after 5 years, or even 3?
In his second video, he does not use the gannister. He only uses fiber blanket and Zircon W., and brings it all the way to the top.. In his rebuild video, it appears that he only used 1" thick fiber blanket, but, when he rebuilds, he uses  40mm=1.5" thick Fiber blanket with Zircon W. Maybe he figures that is plenty of insulation, and moves to ether 2" or 3" of insulation and Zircon W in his future build smaller furnace..  In the rebuild video, he does not show coating the top with Zircon W, but, in the smaller furnace build, he does have a short incert of painting it..
Anyway.. 5 Gallons of the stuff isn't cheap.. But, at $2.00/lb, not bad.. I think without looking at my notes, close to 60lbs in 5 gallons. $120 plus shipping.
Still have to decide between one of a couple of products..
The blanket is not cheap, but, the best price I have found on 8# 1" x 24" x 25 feet $33.44/roll +66 ship =$99.44 which isn't too bad..
link removed
Then, have to get something for the floor of the forge.. Which would be another 55lbs of Plastech 85, which I would only need 2 or 3 lbs ($130 with shipping roughly).
So, I might go with a trial of Aluminum Oxide and fumed silica mixed with Sodium Silicate and hope the binder does what it is supposed to do, which would also be reflective for about the same price and still have a bunch left over but have something that can be used in other places..
Thinking: If Matrikote has a phosphoric Acid base (flux resistant), and Zircon W is designed to be places with molten metal would also be flux resistant,,, I would bet that Zircon W or it's replacement would come in a powdered mix, and could be mixed thicker, which would actually increase it's acidity level, it could most likely be used in place for both a Rigidizing IR for the blanket Plus a rigid coating for the floor if mixed thicker.. Or, according to luckygen,, (zircon is a flower base product designed to stick to anything), could be painted thick over a firebrick base in the forge also reflective, an be back to a blanket an one additional product for a complete build..
I think you can see where and why my thoughts are when looking at these products..
BTW.. I read somewhere that you could put new life back into Matrikote by adding more powdered phosphoric Acid to an old product..  I don't know in what quantity.. Would have to dig into a bunch of MSDS sheets to see if I could locate it in percentages without too many competing products in the mix..
Just thinking outloud..
If it worked great, and more people tried it and liked it,, then, we would have more re-marketers of the product,, and hopefully, could get a reasonable price on it..
I have on my todo list to contact boiler repair companies to see if they have leftovers of what I am looking for, but, have not made it to that point yet.
Shame,, I don't even have any of those anywhere close to me. Closest I have found is 4 hours away in South Carolina..
But, I would bet that, if someone did a full length video with these products, already cut out and ready to install.. Just the assembly of the forge,, and posted it on a few forums like this,, you would see pretty quick, a lot of people building with the same products. I wish I had more time, and could get a reasonable price on shipping.. I would try it myself, just to prove a point.
Thanks for your comments again.. I have to get back to work...

 

[Binesman]

Mark i built my forge as 2 1" layers of ceramic blanket ridgidizes with fumed silica/water a 1" layer of kastolite 30 then painted on a layer of matrikote90ac that was about sourcream consistancy(mixed a little thicker than its supposed to be).  It works just fine the forge gets hotter than before i added the matrikote and holds its heat much better.  It does seem to take a few more minutes to come to heat but that is to be expected when you add any amount of thermal mass.  The one thing i have noticed that is different from a forge that has matrikote added directly to the blanket is that when you bump the walls with your work the matrikote scrapes off of the kastoloite easier than it does the blanket. 

[Mark Thomas]

On 11/15/2017 at 4:50 PM, Jasent said:

Making the outside hard or even 1/4" penatration isn't going to help much in my opinion. Reasoning for rigidizer is to stop or greatly slow shrinkage and to give a firm base for refactory without inhibiting insulative property's.

Your description of "Dried out Sponge" is interesting, because, like you said,, keeps the insulating properties of the blanket, which is why you install it in the first place..
So, surely for a Rigidizer, it is doing it's job.. I would think that is a perfect property for a rigidizer.
Your statement: " Reasoning for rigidizer is to stop or greatly slow shrinkage and to give a firm base for refactory without inhibiting insulative property's."
Agreed.. Let me ask about that...
Why do you put the Refractory over the blanket, and then an IR over that?
Is it because you have not found a product yet that does both? (Protect the blanket and has IR properties?)

In my last post (reply to Frosty), I mentioned.. How much is enough, relating to IR.. 
Is 1" of IR more effective than 1/4" or 1/8" IR coating? How much IR coating is required to reflect back the heat in the forge to keep it from destroying the blanket?
 
The reflective coating on the back of a mirror is paper thin, but, it would reflect the suns heat away from the substrate behind it and reflect the heat forward..
I realize it is not apples to apples but, probably would qualify for apples to oranges..Ha..

What is more important at this point of the forge... When you look into a forge, it is definitely hot just under the burner and progressively cools down as you move away from the burner, even though the fire breathing dragon has dragons breath blowing out 12 inches from the opening of the forge, but, the face of the forge is not glowing, neither is the area of the forge away from the burner.. All normally aspirated forges have to have at least one open end, or the burner won't work with the back pressure.. The cool air mixing is having some cooling effect in the forge.. Any moving air that is a lesser temperature than something around the heat source is going to suck heat out of the forge..

Is the Reflective coating, reflective more than on it's face? Like a thin coating of reflective material on the mirror back? What if it were 1" thick? Would it be any more effective? I think at this point, the IR properties are done and satisfied and we are only looking for "Physical protection" of the blanket..
I wonder what might be more protective to the blanket..  1/2" of Insulating refractory, or 1/8" of IR coating? (And agreed, both would be better, Refractory better than 1/8" coat of IR)..

I think back to the video of the Luckygen1001 furnace rebuild. The inside of the furnace looks pretty good for 5 years of service.. Zircon W over Fiber Blanket.. The outer of the blanket in inside of the metal case is packed gannister(fireclay and silica sand mix).  The top of this is what is looking bad.. But, he does say it was cheap.

I am pretty careful when moving stock into or out of my forge, even though it has a thin layer of blistered and cracked factory refractory over it, and, I am not going to hurt the bricks by bumping them with my tongs, or stock.. Would an IR coated fiber blanket be enough for me? Yet to be seen, but, it appears it would.

 

[Mark Thomas]

On 11/15/2017 at 7:41 PM, Binesman said:

Mark i built my forge as 2 1" layers of ceramic blanket ridgidizes with fumed silica/water a 1" layer of kastolite 30 then painted on a layer of matrikote90ac that was about sourcream consistancy(mixed a little thicker than its supposed to be).  

Interesting.. I thought that might be the case.. It does say not to use it on refractory on this site..
link removed
I have the firebrick forge and a coal forge.. The firebrick forge.. One of the things I like about it, is, it fires up quickly and comes to heat quickly. The outside of the firebrick takes a very long time to heat up.. You can still hold you hand on the bricks after 15-20 minutes of forging.. I have never seen it hot enough to keep a set of your fingerprints..
I must confess.. The most amount of my forging takes place during the winter, so, I would imagine the cool air currents help that quite a bit, but, I don't think it is the rule of thumb of why it doesn't get that hot. Even warm Summer air is going to move when it gets next to something hot.. Just not as fast..
Where I live in the Gorge here, I can guarantee you some wind(thermal currents), on a hot day, just as soon as the sun goes over the mountains.. It is quite significant on a hot day.. They settle down pretty quick.. I would say 1 hour on a hot day, less on a cool day or a day without direct sunlight on the ground.. It is just temperatures evening out since the significant source for the differences is gone..
2-1" layers of Ceramic Blanket is pretty good insulation from what I understand... More so, if you coat each layer individually with rigidizer from what I read..

So,, since it appears it takes longer to heat up, that is either because of the thermal mass, or, some property of the Matrikote not working properly due to being installed over refractory, or, the fact that if that wasn't a problem, there is still a significant amount of heat transferred through the Matrikote,, which might only be up to some point, that the IR kicks in.. Which might be after the forge heats up quite a bit and starts getting in the Orange neighborhood, where maybe the reflective properties of the IR are more effective.. That would make more sense about it getting hotter, and then, holding the heat longer, but, might be voided out due to the extra mass. Voided meaning, can't pin that down either..
Man.. This physics stuff has more legs than a den of spiders...ha.. Seems near impossible to pin anything down for certain..
Thanks for your comment.
If I have time to make it to another hammer inn, I will go and most of my focus will be on how each of the forges there were built..

[Jasent]

The more I think about this the more I can see Matrikote or any IR reflectors be beneficial under the refactory since the source of IR is the refactory once up to those temps where IR is emitted.  Not as a rigidizer but as a pre coat to refactory. It seems I have some reading todo

[Latticino]

A lot of reading I think.  What IR do you anticipate the layer under the refractory is exposed to?  If the refractory does not reflect all the radiation within the forge it must absorb it(basic physics).   However it does reflect a significant amount, or non-IR coated forges wouldn't work, so the inner face of refractory will always be radiating more energy than the outer face, making placement of the IR coating on the outer face less effective. 

Ideally we want to keep the bulk of the heat inside the forge and not let it be transferred to the exterior of the forge.  There are three mechanisms for this heat to be transferred: conduction, radiation and convection.  The convective losses are mostly from heat loss of the combustion products gasses and any dragon's breath that exists the forge openings (minimize with good doors, appropriately sized combustion chambers and slower flame speeds).  The conductive losses are due to imperfect forge insulation (the heat transfers through the forge liner till it reaches the outside of the forge, then convects and radiates to the surrounding environment).  The bulk of the primary radiative losses are also through the forge doors, where you can see visible glowing from the forge interior (though a very poorly insulated forge can have significant radiative losses from the outer skin - if you see the forge skin glowing you know this is taking place).

I am not sure how the mechanism of the IR reflective coating works, but while theoretically it will help block radiation between layers of forge lining, I doubt that is the best use of the material (even if it continues to function with the surface pores covered by refractory).  I believe that conventional theory is that the primary heat transfer process within the walls of a heating chamber is by conduction, not radiation.

[Jasent]

From what I found today it may help protect the wool from the radiant heat of the refactory. Once your forge is up to temp the refactory is radiating IR and not just toward the bolus or forge chamber.  Still a lot of research todo before I change anything in my forge builds though

[671jungle]

reading through and researching and can't find info on what kind of fumed silica to use. I've seen hydrophobic, aerosil?, amorphous. Are they all the same/colloidal? Joann fabric sells amorphous silica which is the same as the RC rigidizer 23 I let freeze and waste. Is there a reliable brand I can buy?

[MaxwellB]

I purchased  1 Quart, Fumed Silica, Thicker,Resin Filler 1 Quart Pack

Planning on doing the home-brew mentioned above, 1 cup powder to 1 pint water, with a pre-spray of water so the rigidizer penetrates better. Then I'll be coating the rigid blanket with the refractory that came with my forge. After reading the back and forths above, I'm left with a few questions:

1 - Should I look into an IR-reflective coating to go over the refractory, or will it be diminishing returns due to the extra amount of material in the forge needing to get hot to get to proper temp?

2 - Should I get a water glass/kiln wash product for the firebrick that'll be the floor to prevent it from getting damaged due to flux?

2a - Can I use water glass as the IR-reflective and kill two birds with one stone?

[HojPoj]

I'd advise not having water glass (sodium silicate) anywhere exposed to the flames. 

You have options for flux resistance.  Yes, a kiln wash is one way to achieve it- though you'd have to be very gentle in handling to account for its fragility.  Another choice would be a sacrificial floor piece (or 'pan') made of flux resistant material that only gets put in when needing to forge weld.  Given that it's probably a hard firebrick that'll make up the floor, that's a fairly expendable item anyways.  You could get a flux-resistant refractory and just cast additional floor pieces.  I think the more important thing here would be keeping flux off the walls since they're not as easily replaced... and flux getting into ceramic wool melts it like water on cotton candy.

 

[671jungle]

Any one have any thoughts on this? i cant seem to find the differences.

[ThomasPowers]

Did you google: silica hydrophobic site:iforgeiron.com   Seems to be easy to find that way.

[671jungle]

16 minutes ago, ThomasPowers said:

Did you google: silica hydrophobic site:iforgeiron.com   Seems to be easy to find that way

Thanks Thomas! I totally spaced the google plus I Forge Iron tip on that one.

[ThomasPowers]

One of the esoteric rituals required for using this site effectively---much like the lamentation for the loss of the earlier photos...

[Mikey98118]

On 11/16/2017 at 12:49 AM, Mark Thomas said:

In my last post (reply to Frosty), I mentioned.. How much is enough, relating to IR.. 
Is 1" of IR more effective than 1/4" or 1/8" IR coating? How much IR coating is required to reflect back the heat in the forge to keep it from destroying the blanket?

The inconsistency here is found in  advertisements for "heat reflective" products, which is a legitimate label, if inexact. Then, advertisements went further, and called various products IR reflecting, which departed from reality. All of these products are re-missive coatings; most of them use zirconia powder to absorb heat and emit light as a result. If you think of millions of tiny particles on a surface being heated up and radiating energy in all directions, than about one-half of the radiant energy will be bounced back in the direction of the heat source, and the other half will move on away from it. Now think of another layer of particles behind the first one; this will become heated by the radiant energy of the first layer, and will bounce back about half of it. With each succeeding layer about one half of the transmitted heat will be bounced back toward the heat source. Since the zirconia particles are tiny, it doesn't take a very thick layer of them to "reflect" most of the incoming heat back toward its source; about .040" is considered as insulation.

Zirconium silicate is about one-third silica, so it takes a thicker layer than zirconium oxide (zirconia) to do the same job, but then it is also less far expensive and much easier to employ, too. It is a fact that the smaller the particles of zirconia the greater the percentage of heat "reflection" they permit (as low as 68% to as high as 95% if I remember correctly). The zirconia particles trapped in the silicon matrix of commercial zirconium silicate are colloidal (minuscule).

Zirconia crucibles employ very crude particulates, and yet they are so effective as insulation that they become the entire furnace, when wrapped in a coil, and insulated by a further layer of loose zirconium oxide.

So to answer your question, the thicker the better, providing you use it in a manner that will stay attached.

 

[CrustyBasset]

I hope it's not too forward but the info Frosty provided in this same thread on Nov 9, 2017 is so helpful to amateurs I wanted to compile it into a bullet pointed list that might be helpful. From the info Frosty provided the bullet points below are just an extraction of his info into an outline. There are two deviations from Frosty's info (noted) in the steps with explanation for the deviations. The deviations may not be valid but throwing them into the mix in case anyone can confirm whether they are/aren't valid to include. 

I'm an amateur who bought a furnace from a great guy who runs the backyard metal casting site and have built some custom small amateur forges and a waste oil burner but haven't yet really put any of it to productive use - mainly due to the day job.  Thanks. 

 

STEPS TO LINE WALLS OF FURNACE/FORGE INTERIOR 

- DEVATION FROM FROSTY'S INSTRUCTIONS: 
     - brush a coating of sodium silicate onto the inside metal interior of the furnace 
        - REASON FOR DEVIATION: just for adhesive to bind the kaowool to the metal  
- First layer of kaowool: 
        - line a 1" layer of kaowool around the inside metal interior of furnace - sticking it to the sodium silicate 
    - rigidize the first layer of kaowool
            - mix 1 cup Colloidal silica with 1 pint clean water and add the mixture to a spray bottle 
            - Spritz the kaowool with clean water first to butter it - this will allow the colloidal silica rigidizer to penetrate more deeply
            - Spritz the kaowool with the rigidizer 
            - Fire cure the outside layer now, a Bernzomatic torch will do the job nicely, just bring it up to red heat, that's plenty. 
- Second layer of kaowool: 
        - prepare a second 1" layer of kaowool that will be placed on top of the first layer of kaowool 
        - before placing second layer on top of first layer: 
            - spritz first layer with clean water 
            - spritz the side of the second layer that will set against first layer with clean water 
            - spritz the side of the second layer that will set against the first layer with rigidizer 
        - place the second layer on top of the first layer, with the side of the second layer that has been rigidized set against first layer
    - rigidize the inner surface of the second layer of kaowool
            - Spritz the kaowool with clean water first to butter it - this will allow the colloidal silica rigidizer to penetrate more deeply
            - Spritz the kaowool with rigidizer
            - Fire cure the second layer now, a Bernzomatic torch will do the job nicely, just bring it up to red heat, that's plenty. 
- Press the liner with your finger, it shouldn't compress without pressing hard. If it does compress butter and rigidize it again.
- Once the insulating outer liner (Kaowool) is dry and flame cured, cut your burner port(s). 
        - I use a sacrificial hole saw, don't hog it and it won't tear the rigidized Kaowool. 
        - Drill it over sized so you can plaster it with the flame face refractory. 
- DEVATION FROM FROSTY'S INSTRUCTIONS: 
        - apply coating of Matrikote to inside face of rigidized kaowool 
        - Let the Matrikote dry and flame cure it to red heat, let it cool.
        - REASON FOR DEVIATION: if radiation can indeed absorb through refractory, this coating of Matrikote would be an added layer to 
            reflect the heat back to inner furnace.
- Once you have all the mechanical mods made it's ready to lay in the hard refractory flame face. Recently "Kast-O-Lite-30 hi." has 
    become the popular consensus "best stuff." It's a castable, 3,000 f. high alumina, bubble refractory. It is concrete hard at 
    it's top operating temp 3,000 f.
- Mix the refractory with only enough water to make it workable (The wetter you  mix it the weaker it is when cured.)
- Butter the kaowool and plaster it approx 1/2" thick with the hard refractory.
- Once set the recommendation is to keep it at 100% humidity between 70 f. - 120 f. I just wrap my castings in a wet towel and give it 
    over night to finish setting and do some curing.
- apply coating of Matrikote to inside face of rigidized kaowool 
- Let the Matrikote dry and flame cure it to red heat - mount your burners bring it to red heat, let it cool.
- It's ready to go to work.

[MT Hammer]

Hmmm, I've obviously stuffed it up here.  I bought some fumed silica (System Three 3105S16 on Amazon), mixed it as specified, and added some ag blue dye. Spritz the kaowool with water, and after letting that soak in a bit, proceeded to saturate it with the rigidizer.  It looked like this (every probability I put in too much blue dye!)

After it dried (took several days), I then attempted to cure it with the MAPP gas torch.  The blue burned off as I got it all red hot, and that left it looking like this:

The PROBLEM: It's not really rigid!  It is a bit more rigid than it was before, but still kind of spongy. It's like a stale pound cake.

As this is my first build, I'm not entirely sure how rigid it should be. I'm guessing though if I tried to apply the Kast-O-Lite over this, I'd have problems.

Think I used the wrong fumed silica, mixed it wrong, used to much/little, or didn't utter the right incantation.