Confused about Rigidize

[MOguy]

From what I understand Rigidizer what I need to help make ceramic blankets safe I am searching and find posts about how people wanting to make rigidizer and it being expensive.  I find people saying to spay it on the blanket, other say soak it.  Other have different information about how to mix it. 

 

I found what seems to be rigidizers used for forging and coating ceramic blankets for what seems to be relatively inexpensive.    Do I spray it on or soak it?

 

 

 

[Irondragon Forge ClayWorks]

I spray on the rigidizer using an old cleaner spray bottle with a couple of drops of food coloring in it so I can see the coverage I have. You will notice if you ask ten smiths a question you are likely to get nineteen different answers.

[Buzzkill]

You can make your own rigidizer with fumed silica and water.  It's much cheaper that way.   There are two types of fumed silica: Hydrophobic and Hydrophilic.  We use hydrophilic (meaning it dissolves in water in this context).  Fumed silica is also referred to as Silica Thickener or Colloidal Silica in some instances.

[Mikey98118]

As to safety, it would not be my first choice. A seal coat provides better safety. What the rigidizer is BEST at is helping to under-gird the physical structure of the seal coat; it also helps prolong the life of the insulation itself. As to protecting your lungs from fiber dust it is better than nothing, but nowhere near is good as a good seal coating.

[MOguy]

On 11/13/2018 at 11:22 PM, Mikey98118 said:

 

The forge I ordered claims to have rigidizer on the blanket.  Can the seal coat be placed over that?  When you say seal coat do you mean refractory cement such as this:

https://www.amazon.com/MEECOS-RED-DEVIL-611-Refractory/dp/B002OU2Y62

[John in Oly, WA]

That Red Devil stuff is mortar. Meant to use between firebricks for setting them. Generally doesn't hold up to direct flame contact. You want something like Kastolite 30, or Mizzou castable refractory.

As for rigidizer, or shopping for anything online, search, search and search again. I've found prices vary widely(wildly). I've found a gallon of rigidizer for $32US and the same gallon of rigidizer at another location for $102US.

Another time I was looking for a coil for my go cart. One online source had the coil, spark plug and CDI for $11US. Another source, just the same exact coil for $125US - claimed it was high performance.

[MOguy]

6 minutes ago, John in Oly, WA said:

That Red Devil stuff is mortar. Meant to use between firebricks for setting them. Generally doesn't hold up to direct flame contact. You want something like Kastolite 30, or Mizzou castable refractory.

As for rigidizer, or shopping for anything online, search, search and search again. I've found prices vary widely(wildly). I've found a gallon of rigidizer for $32US and the same gallon of rigidizer at another location for $102US.

Another time I was looking for a coil for my go cart. One online source had the coil, spark plug and CDI for $11US. Another source, just the same exact coil for $125US - claimed it was high performance.

Thanks for the info on Kasto and Miz. When I was searching for rigidizer to saw the same thing.  Auto parts are the same way.  

[Mikey98118]

Did you hear the one about the guy who turned a silk purse into a sow's ear? Constructing a forge is like building a brick wall; it take a few simple and easily understood steps; which cannot be ignored without making a mess.

The price of rigidizer certainly does vary wildly, as it is an end product. But you can get fumed silica powder through eBay without paying for shipping and at rock bottom prices. You can also get the same product wherever fiber glass products are sold locally, if you're in a tearing hurry. Fumed silica is an ingredient in dozens of products, including milk shakes. The closer you come to basic ingredients the less you pay for forge materials. The more "marketed" a product is the more ignorance tax you'll pay.

Silica based ridigdizer is fumed silica mixed in water, with a few drops of food coloring die to make it easier to judge penetration. Dump a little silica in water. Too much and it gets too thick to run through a spray bottle's nozzle, and needs more water. Too little and it becomes ineffective, until you add more fumed silica to the water. Add food coloring to suite; it burns out during firing.

You can spritz the silica unto ceramic fiber insulation and it will greedily suck up the silica; You can paint it on; you can dunk the fiber in a rigidizer bath; any excess will run off of the ceramic fiber insulation, just like excess water.

There are few things in life that are as easy as buying and using fumed silica; do it simple and easy are complicate it all you want. In the end it will turn out fine, with or without a bunch of hand wringing.

[CactusBob]

If your looking for Kastolite lookup Wayne Coe here on IFI, he sells small quantities for a decent price at his website

[Yanni Rockitz]

On 11/15/2018 at 2:24 PM, Mikey98118 said:

There are few things in life that are as easy as buying and using fumed silica

Man -- the old saying goes something like, "If there's a 50/50 chance of getting it right, I'll get it WRONG every time."

I read about the gas forge lining for dozens of hours on here -- reading more, repeatedly, over a couple of years, as I slowly evolved my thoughts on building one. It's like Google -- there's TOO much information and a lot of it is focused on specific processes that only give you part of the story. I've only found an actual procedure two, maybe three times -- all a little different. They're similar, but often with different products for different 'layers' and some have changed over time. The ceramic blankets are pretty straight forward, but the refractories -- Mizzou vs. Kast-O-Lite 30 vs. Satanite, etc. -- have different arguments. Then, the final IR reflective coating seems to be the most mysterious bit to get a consensus on. I thought I'd arrived at a solid understanding about a year ago for two 1" layers of ceramic wool fiber blanket, rigidized -- each, in turn -- then two 1/4" layers of Satanite -- each air dried then progressively cooked in to cure, then ITC-100 for a final IR reflector, so I ordered all that. Now I've found people saying ITC-100 gets 'chalky' (so... don't use it?)

When I rigidized the ceramic blanket, I found that my fumed silica "202" doesn't mix in with the water in the spray bottle at ALL -- like HATES water -- floats on top. I kept shaking it vigorously, as suggested here on IFI, spraying it on, but eventually clogged up the sprayer. It doesn't say on it anywhere whether it's hydrophobic (or hydrophilic) -- just that it's a thickener often used in epoxies. Urgh. It was well covered by the time it clogged, so I set it for several days by the wood stove in hopes some of the silica got mixed in, but now that it's dry, it's not even the slightest bit rigid -- still feels like out-of-the-box, soft, puffy ceramic wool blanket -- it's just blue, now. Apparently zero silica made it through -- only blue water. More reading, now I find this, above, noting hdrophilic (mixes with water) vs. hydroPHOBIC fumed silica. 50/50, so I got it wrong. Clearly, I got the hydrophobic stuff. It certainly doesn't dissolve in water, no matter what level of foul language I apply to it. I just bit the bullet and ordered some Inns-Tuff rigidizer, as I've read a few of our heroes have used with good results. $16 for a quart seems reasonable. For future re-linings, does anyone know where to get the water-friendly hydroPHILIC fumed silica for a good price?

[Frosty]

9 minutes ago, Yanni Rockitz said:

Man -- the old saying goes something like, "If there's a 50/50 chance of getting it right, I'll get it WRONG every time."

Oh COME ON Yanni, NOBODY is perfect!

If you still have some of that fumed silica, try adding a LITTLE "Jet Dry" dishwasher rinse air. It's a wetting solution, it breaks down the surface tension that prevents many hydrophobic materials from getting wet. 

Also you need to heat the silica rigidizer to red heat to fuse the ceramic blanket fiber intersections together and stiffen it up. 

I bought hydrophilic fumed silica at a local plastics supply and contractor. I described what I was doing and the guy at the counter told me I had the wrong stuff and got a different can. Neither said philic or phobic on the label and neither cost enough to be worth mentioning. $8/lb meant a pint can cost more in repackaging and labeling than the silica. 

I'm with you on how confusing it can be reading Iforge posts even being broken down into sections and subsections. Products, techniques and information evolve. For example Mizzou is still a high end castable refractory but other products have come to our attention that have properties that are superior. Kast-o-lite-30 for example is high alumina making it much more resistant to borax based welding fluxes. Another advantage is it being a "bubble" refractory, evacuated silica spherules replace some of the aggregate, they offer increased insulation and decrease the physical weight. 

Yeah, ITC-100 has become a legacy kiln wash for propane forges but it just doesn't work very well. Plistex 900 fires hard like a ceramic glaze and is very high alumina. The stuff laughs   at molten borax fluxes. BUT it doesn't contain ANY zirconia so we don't enjoy that layer of IR re-radiance. Zirconia containing kiln washes like ITC-100 do NOT reflect IR, they absorb energy because they aren't good conductors then they Radiate it in the direction with the least resistance. Seeing as the product is painted to a thicker refractory the easier direction to radiate IR is back into the forge. Not all of the heat but enough to be worth it.

A couple fellows here have experimented with things to make refractories and kiln washes, myself included. I'll make another attempt if I make another forge, not for the sake of experimenting though. Marten in the Netherlands IIRC was getting some excellent results with 97% zirconium silicate and 3% Bentone, a type of bentonite clay.

Plistex is an easy to get kiln wash and works a treat, don't let a bunch of talky tinkerers muddy the waters for you. Eh?

Hopefully this is more help than added confusion. If I raised ore questions or you need clarification give a shout I'll try to clarify in a less rambly manner.

Frosty The Lucky.

[Mikey98118]

an -- the old saying goes something like, "If there's a 50/50 chance of getting it right, I'll get it WRONG every time."

Ya gotta love this guy; in one saying he has summed up so many lives; certainly, he's hit my main fear dead center.

Keep on trucking Yanni, Some day, you'll be writing excellent how-to books. Hears another old saying. "it takes one to know one."

Frosty gave you good advice. Plistex 900 is the simple, straightforward, inexpensive answer. Of course, if you feel the need to wander in the wilderness a little longer...there are lots of high-tech super-cool solutions, which we will be glad to mention. Jump right in; the waters fine down here at the deep end of the People's Pool-honest

[Irondragon Forge ClayWorks]

My wife likes to call me Christopher Columbus, because I don't know where I'm going and don't know where I am at when I get there.

[ThomasPowers]

But he was a pretty great sailor to get there, (and back!)

[Frosty]

Wanna bet the Queen looked at it like the bad penny turning back up?

Frosty The Lucky.

[Yanni Rockitz]

Ha! How did I miss all your replies for two full months!?! The whole gang chimed in.  :-)  

IronDragon -- I'm stealing that one. Columbus! lol

Mikey - SO true, right?! The secret is to apply your 50/50 chance (i.e., 100% guarantee of initial failure) to challenges that you actually enjoy -- then the mistakes end up appreciated as stripes earned in the trenches and finding the right answers, at last, is a rich reward. (I wish I knew that when I was 20!) Everything I've really enjoyed in life has been either luck, accident, or elective -- and the mistakes and errors were often the most valuable learning bits. No one MADE me build my boy that tree house, but I loved every minute of it and learned a ton in the process. He could care less about it now, but I still gaze at it appreciatively and now and again climb up there just to survey my little kingdom.

Frosty -- your reply is greatly appreciated! I've read a bunch of that in other posts you've provided along these hallowed halls -- and it's helpful to hear it synthesized again with new insights. I have a day job as an IT guy and I'm constantly grumbling about how every problem I have to research suffers from way too much info out there in Web land -- usually dancing all around the specific issue I'm trying to understand, but rarely answering it directly. One ends up with a skill at gathering loads of ancillary data on the general subject, identifying common issues and solutions and making a best guess at the case in point. So it has been with understanding forge design. IFI is one of the special places where the "too much info" thing doesn't actually annoy me -- quite the opposite -- I always learn something valuable along the way. I just turned 51 and I'm really starting to understand that nothing good comes in a hurry.

The ITC idea was all the latest/best knowledge at the time... I thought I had that final IR flame-face coating thing sorted out, but now I realize I probably found ITC at least three or four years ago (time flies) and I just hadn't seen Plistex 900 mentioned in the interim, despite many hours invested. I finished my propane forge in January with ITC 100 over a couple layers of Satanite, over (sides and bottom) of KastOLite 30, over two 1" layers of rigidized 2800F blanket. I slightly overbuilt it with two Frosty T-burners and she's a right RIPPA -- seriously high temps -- she'll burn steel... but I can't help wondering if Plistex would've let me attain the same result with lower pressures... From the sounds of it, the ITC will eventually wear off, so I'll re-coat with Plistex when that time comes. I took loads of time -- like weeks -- to air dry, then gradually flame cure every layer, starting with the rigidizer, and that patient approach really paid off. Thanks for the good advice! My next forge build will be so much easier. 

Here's an early picture of the new forge -- when it was still flame-curing the final layers. I need to coat a few fire bricks to block up the front and back openings a bit for quicker heats... and a gratuitous fish pic -- because who doesn't love a big bass.

[Irondragon Forge ClayWorks]

Nice forge and bass you have a right to brag about both.

[AlexKelamis]

I've posted this before. I'll post it again.

Fumed silica + water DOES NOT equal colloidal silica. Doesn't matter if it is hydrophilic or hydrophobic. Fumed silica is basically a silicon atom connected to four oxygen atoms, and this pattern repeats to molecules of various sizes. If you add this to water, you simply have fumed silica in an aqueous solution. Yes, if will bind to the surface of your ceramic fiber. But not very strongly--its hydrogen bonds. It can easily be rubbed off. It may seem harder. The hardness you feel is simply a dried caked layer of fumed silica powder. Now, at room temperature fumed silica powder is not as dangerous to inhale as ceramic fiber dust. However, if either are heated, they both become extremely dangerous. 

Water glass is made by adding sodium hydroxide to an aqueous solution of fumed silica. If you take this, heat it and use catalysts and chromatography or some other purification method, you end up with colloidal silica. It is not easy, and you aren't going to do it in your kitchen or workshop. 

Colloidal silica is a repeating structure of silicon atoms, each one bound to three oxygen atoms. They form an amorphous structure, meaning there is no definite pattern. It's random. Along the periphery of all these bound silicon atoms and oxygen atoms you will have tons of hydroxyl molecules. These are very water soluble. This is why the colloidal silica dissolves in water. 

Hydroxyl molecules react readily and easily with the oxygen atoms present in the ceramic fiber structure. This quickly forms a covalent bond between the two. It isn't going to mechanically be removed. Once dehydrated, it is going to be rigid because the colloidal silica penetrates into many of the "air pockets" to fill those without changing the thermodynamic properties (much). When you heat this, and drive off the last bit of free water, the colloidal silica becomes even more bound to the ceramic fiber and therefore even more rigid. Therefore, no dust particles fly off. 

You don't get this with fumed silica. Period. Maybe fumed silica is "good enough". Or maybe not. I can't say with 100% certainty. But I can say this, it's one or the other. It's either safe enough, or it isn't. 

Restrictive lung disease, like progressive massive fibrosis from breathing in silica particles, is really not cool. By the time you know something is wrong, it's too late. Oh yeah, it will also damage your kidneys, and ultimately your heart. It can also cause severe damage to joints and skin, but who cares at this point. You just want to be able to breath. 

Most of us will probably be fine.  But, about 15% of the people reading this will have a genetic mutation that makes them extremely susceptible to developing the deadly lung disease (and kidney, heart, etc.) associated with ceramic fibers. For that 15%, it takes very low levels of exposure, and it will cause terminal (ie: you are going to die) disease in as little as 3 years. So, this means roughly 1 in every 7 people reading this are high risk for developing deadly disease, and quickly. What group do you think you fall into? Are you willing to bet your life on fumed silica working? 

I don't claim to be in expert in everything. But I do know what I am an expert in. I'm not talking out my backside with this. 

We need experienced blacksmiths with the chemical knowledge background to chime in on this. We need to make sure the advice being dessiminated on these forums is safe and sound. There are always exceptions, but we need to make sure we are setting other up for success in their future, not deadly medical problems. 

I am all open for comments. What are your thoughts?

 

 

 

 

 

 

 

 

 

[Frosty]

Just the same questions you didn't respond to last time you said this. I'll refine them a little today.

#1, In what way is fumed silica not colloidal? Fumed silica remains suspended in clean fresh water without settling out. A definitive example of colloidal. #2, What definition of colloidal are you applying to the subject? 

The necessary bond it forms with refractory fiber is mechanical when fused, not chemical. 

Sodium silicate has shown by empirical evidence gained through years of experience to NOT perform as well as colloidal, fumed or otherwise silica. The rigidized and itc-100 kiln washed 8lb. Kaowool refractory blanket, roof in my old shop forge is more than 15 years old and still stiff. It was rigidized with colloidal silica fro the plastics supply in Anchorage, fumed is the only colloidal silica they carry, hydro phobic or hydro philic. it's used primarily to thicken resins. 

Once again you've posted text easily cut and pasted that does NOT match or have anything to do with empirical evidence. You include zero cites, not even a bibliography or link. 

Until you actually support your statements with evidence they're just cut and paste gum flapping. 

So far you've posted 5 times, every one pretty much just like your most recent. Unless you back what you say this is the last time I'll respond to you. I do NOT FEED TROLLS.

 

[Buzzkill]

Regardless of what else is true, if fiber blanket is rigidized and then covered (sealed) with a castable refractory (which is what we recommend), the chance of airborne particles escaping in the concentrations that cause health issues is negligible at best.

[rayanwick]

On 4/30/2022 at 11:37 AM, Frosty said:

Just the same questions you didn't respond to last time you said this. I'll refine them a little today.

#1, In what way is fumed silica not colloidal? Fumed silica remains suspended in clean fresh water without settling out. A definitive example of colloidal. #2, What definition of colloidal are you applying to the subject? 

 

 I would like to address some of your points in order to clarify the definitions of colloidal silica, fumed silica, and hydro phobic silica.

First, for colloidal silica, you're correct that it does not have a chemical bond with refractory fibers. However, this does not mean that it doesn't form a mechanical bond with them. When sodium silicate is fused with refractory fibers, it forms a non-chemical bond that is mechanically more stable than the chemical bonds formed by other materials such as fumed or hydro phobic. This explains why sodium silicate has been shown to perform better than other types of silica in kilns.

Second, you state that hydro phobic silica is used primarily to thicken resins. However, this is not true—hydro phobic silica is used primarily to purify resin during the manufacturing process. It does not have any other uses in manufacturing equipment or equipment components. Hydro phobic can be used for its other beneficial qualities, but these are secondary benefits rather than primary reasons for using hydro phobic

Edited August 10, 2022 by Mod30
Trim quote.

[Frosty]

Changed your login name and resubbed did you? Once again you show how poorly you understand what you read, let alone search. Point by point. Where is your clarification of the definition of colloidal silica? Not a word. Again no clarification, you could've said, sorry you were right, re how colloidal silica rigidizes ceramic fiber refractory. Nothing you just said clarifies a thing. That's two nothings. Lastly, we don't purchase industrial quantities of anything let alone rigidizers, at our level hydrophilic silica is sold and used to thicken 2 part resins, there are chopper guns designed to add fumed silica to the mix being laid down. That's 3 strikes.

Googling things does you no good without actually looking into what it means and if you can't apply what you read to what something is being used for then you'll keep striking out on "clarifying or explaining" anything. Just popping off with poorly understood non-applicable factoids doesn't make you look educated let alone smart. 

Are you familiar with the old adage, "It's better to remain silent and let people think you're a fool than open your mouth and remove all doubt"?

Frosty The Lucky.

[JayTheGlassMan]

I agree with that your wording is too ambigious,  in nano or small things. It seems only the important or functioning or important parts are labeled. I am here because i am melting the silica into my Ceramic blanket today, maybe id catch a tip here. I got er done though. Im securing it to its walls because I feel better having it held in with something METAL :x..   I am 200 hours into my nothing to something project, built a worktable with roofing and shelves and a kiln out of scrapish materials. If any1 wants to check it out Id be delighted to share a pic. I am journeying on this path progress myself as a human and kick out the crutch that society holds our stupid naive xxxxx up with.

Edited August 10, 2022 by Mod30
Language

[Frosty]

What do you do, join under a different login every time you want to post? 

Does your mon, dad or caretaker know you're online? 

Frosty The Lucky.

[Mikey98118]

On 7/30/2022 at 4:46 AM, rayanwick said:

First, for colloidal silica, you're correct that it does not have a chemical bond with refractory fibers. However, this does not mean that it doesn't form a mechanical bond with them. When sodium silicate is fused with refractory fibers, it forms a non-chemical bond that is mechanically more stable than the chemical bonds formed by other materials such as fumed or hydro phobic. This explains why sodium silicate has been shown to perform better than other types of silica in kilns.

Water glass cannot stand up to the expected temperatures at the cold face-side of a 1/2" layer of hard refractory layer, which most of us recommend as a seal coat, flame face, and physical armor layer between super-heated forge atmospheres, and insulation layers. At the temperatures used for welding in forges (and by most smiths for other work as well), the "cold" face of the hard refractory will be running around 2200 F, and sodium silicate will have melted, leaving the ceramic fiber loose again, so that it can turn into broken tiny bits of carcinogens. Sooner or later the smith will have to reline his/her forge; opening up that mess to the air.

I think it's great to warn against health dangers, but let's keep the picture straight.