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plastix 900F.jpg

Plastix 900F is painted on about like thick latex paint as a final bit of armor and IR re-reradiator. (meaning it gets really hot and radiates heat back into the forge).  IR reflective coatings are Plistix or Metrikote,

Plistix 5 pounds for $45.00

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  • 3 months later...

5 pound of Plistix 900F applied at a 1/16 of an inch thickness will cover approximately 6 square feet.

The IFI gas forge discussions suggest that Plastix 900F be applied to the Kast-o-lite hard refractory to reflect heat back into the forge and improve fuel economy.

 

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  • 2 months later...

I did not understand answer from above will it stick to a rigidizer on Kaowool. I have ceramafiber Ceramic Fiber Blanket - Insulation 1" thick. I sprayed it twice with Simwool Rigidizer and after Frosty & others saw my forge they suggested to use this product over existing pictures of forge I showed them & remove the fire brick I now have in there. Will this stick to my existing fiber blanket w/simwool ridigizer. I plan to apply it thick as suggested. You can see my forge pictures on a form called HELP.... I created, Any input you have will be appreciated.

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Yes, either Plistex or Matrikote will bond to ceramic fiber refractory but it's thin and brittle and even rigidized blanket isn't hard just a little stiffer. If you use either product as your hard inner liner you either have to apply several thin coats to provide rigid physical strength or learn to be very gentle with your forge. 

It's called a "kiln wash" because it's typically used as a final layer on the flame contact side of furnace/kiln liners and there are many washes and many purposes. Some act as a release agent in pottery/ceramics kilns so pottery and glazes don't stick to shelves and furniture during firing. Some glazes are chemically active at high temperatures and can attack the inside of the kiln, shelving furniture, etc.

Borax based forge welding flux is a good example of something that becomes VERY CAUSTIC at welding temperatures and literally dissolves silica based refractories. You can literally watch it eat holes in the old soft/insulating fire brick (IFB) and eventually through 3,000f hard fire brick. Toss a little on blanket refractory and it'l like throwing hot water on cotton candy. 

Rigidizer might help protect from hot borax but only a little and I don't know about the stuff you used so I can't say. 

If nothing else kiln wash the blanket but for the money I'd buy a proper 3,000 f hard refractory like Kastolite 30. (KOL) has become a consensus favorite in the last year or so as it's also an insulation so we lose less heat. It's concrete hard to it's working maximum temperature rating of 3,000f.

Frosty The Lucky.

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  • 3 months later...

Frosty, are you just lining the bottom/floor with kast-o-lite and possibly the bricks?

From what I understand, the ridigidizer and plistix, or similar product are all that are applied to forge inner surfaces.

I'm just beginning to learn about forge welding, and am in the process of building my first forge. I hastily ordered likely too much mortar, and not the agreed upon kast-o-lite before I got in here... It's called uni-bond33 from a company in Winnipeg, it says it's rated for 3000°f.

It'salso my understanding that the bricks used for the "floor" are specifically favored by members in the blacksmith world. I have some rated for 2200°f that I'm going to use for closing the front. Many sites I visit are sold out of all the recommended items.. plistix 900f, kast-o-lite, I can't remember what bricks that are suggested.

I have itc100ht on the way to me now, but have been told it's not as good as plistix. I'd prefer to buy as local as I can... at least within the couple surrounding provinces.

I live in Saskatchewan Canada... Thanks in advance!

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This is from Uni-Bond web site.

Quote

This high temperature mortar is a premier quality, alumina-silica, super duty, air setting, mortar that is used for laying, surfacing, and bonding firebrick. It has both air and heat setting qualities. It's excellent working ability, good bonding strength, and high fusion make it a good choice for all types of firebrick construction.

Maximum temperature - 3000F, 1650C.

Seeing as you are planning on using it to coat wool, not sure how well it will hold up. However since you have it on the way, use it and report back on how it does. If it fail's and I suspect it will, chip it out and use a recommended castable refractory.

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The time tested order of layers and products are ceramic fiber blanket two 1in. layers each rigidized with colloidal silica, castable refractory like kast-o-lite 30 in 1/4-1/2in. layer, and a kiln wash/IR re-emmission layer like matrikote, plistix 900 or ITC-100 with matrikote or plistix being the preferred due to price and durability. 

Pnut

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Thanks! This is, and would have been helpful before I started ordering stuff lol.

lesson learned... Join a blacksmith fourm before you get too far ahead of yourself. I'll have to see, maybe I can return the mortar. I will stick with the itc100 since it's coming from the states. At least now I know, I can prevent the mistakes I was about to make.

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2 hours ago, Roudyroddypipper said:

Frosty, are you just lining the bottom/floor with kast-o-lite and possibly the bricks?

I use Kastolite 30 (KOL) on the entire interior as the "Contact Surface) AKA as the "Flame Face", either are valid terms so don't get confused.  In my last forge I gave the whole interior about 1/2" but reading other guys reports I doubt anything but the floor needs that much. However, if you or your friends are ham handed 1/2" will stand up to some hard slammin and jammin. I have a friend who sometimes moves the forge on the table jerking his work around. 

I use Morgan Thermal Ceramics, K-26 IFBs, they are rated for a maximum working temp of 2,600f and there is a margin above that though they don't say what. K-26, IFB aren't susceptible to welding flux erosion and remain hard and strong up to their working max temp. As fast as my shop forge went through IFB I would've been thrilled to pay double, say $22. ea. but . . . OH :o NO!!, they are available in Anchorage Alaska for around $4.35 ea. less by the case. 

You CAN find them online but the seller has to make a buck so online prices seem to run about 30+% higher. Check with your local HVAC service and supply companies. Call them on the telephone and be nice if they don't carry the stuff they'll know who does or where you can find it. You might have to do some detective work, Morgan may not sell in Canada under the same name, or perhaps a subsidiary.

I haven't built a cylindrical forge in I don't remember how many years. I make square or rectangular shells so that's what mine usually look like. My next one will be different but not a cylinder and it won't have IFBs in it maybe (if I do it right) not even for IR baffles.

In my opinion a floor in a cylinder should be only as wide as necessary and something that isn't a huge heat sink. The two approaches I like best is a high alumina kiln shelf of the desired width laid in a notch in the Kaowool outer liner to hold it in place. My other like it method is to fill the bottom with Kaowool cut floor width and feathered on the edges so it meets the sides smoothly. Rigidized of course. Then apply the Kastolite or equivalent water setting high alumina castable refractory as the flame face. In this case I'd definitely make the floor a little thicker as in my 1/2" happy place. 

A final kiln wash is the icing on your cake, again Plistex or Katrikote is preferred for it's mechanical durability. I'll be experimenting on my next forge, probably the 97% zircopax 3% Bentonite mix. I'll be testing it directly under the burners till I decide how it works. That's another season's story, right now it's winter in an unheated shop and I don't think freezing Kastolite is recommended.

Frosty The Lucky.

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On 2/1/2020 at 2:44 PM, Roudyroddypipper said:

It's called uni-bond33 from a company in Winnipeg, it says it's rated for 3000°f.

I've read this on their site too, I have a tub of this Unibond33 and used it to smooth out my brick floor that was pretty beat up. Now I haven't got to many hours in since coating the floor how ever it did seem to start getting tacky where the flame was coming in contact with it once I started getting the forge into the upper orange range. I'm hoping that since I laid it on thick that it was some form of residual curing needed but anyone thinking of this should test it out before going heavy on their whole forge. Only the spot right under my flame was like that the rest seemed solid so either my flame is REALLY hot, it needs to still vitrify or you don't want it as a flame face but it's too early for me to say one way or the other.

 

 

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A couple possibilities come to mind. First, high orange is low for my general forging temp, I typically run mine at low to mid yellow, high orange might be where this mortar starts to melt. Second, propane is very chemically active being in direct contact could be doing ungood things to the mortar. 

The sort of thing I was led to expect using mortar or cement refractories as flame face.

Still, I'm so used to being surprised I'll try  not to faint if this stuff turns out to be a suitable forge liner. Keep us in the loop please.

Frosty The Lucky.

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Like PSI my description of color could be off, I really want to get myself a thermocouple just to see what temps I hit with my forge just for curiosities sake kinda like my pressure gauge in the beginning was used to calibrate my ear now I need to calibrate my eyes. 

I was running hot whatever the color was I know this because my stock was heating faster then I could swap it out for the piece I was working on...... But I wasn't that surprised when it felt tacky due to it being mortar like you say, I need to run it a bit more before I really say yay or nay on this stuff. The the supplier was quite confidant that this wouldn't happen as he sells it as a flame face in other applications so time will tell right.

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We all see the colors we see, what I see as mid yellow isn't going to be the same color other folk see and cameras are famous for false color shooting HOT things. Were we standing next to each other looking at the same fire and stock we'd only be able to agree the color we're looking at is X but we're still seeing the color our brains see. We just agree to call THAT color X. Being able to calibrate with a reliable temp indicator would be really good. 

I've found I have to take anything the guy at the counter says with a grain of salt. The guys at the HVAC service and supply company I've been dealing with for a few decades now have given me a LOT of good info. They are INTO fire and aren't shy about talking. A couple years ago I stopped in to buy ANOTHER box of IFBs (Insulating Fire Brick) while picking up a couple garbage bags of Kaowool drops. When the guy writing me up pulled up my file he noted I'd bought a case not long before. So he asked me if I was building a bigger forge or more. Nope, IFBs just don't last long, I'm lucky if I can bring the forge up to heat more than twice before they start to break up and crumble.

That got everybody in the office's attention and the questions began. NO I'm not banging them around, certainly not splashing water on them or cooling them fast, say with an air hose or blower. One of the guys says, "That sounds like you're over heating them but I don't see how."

To which I say, "How hot is overheated, I rarely run my forge above yellow white." The room literally went silent, "IFBs are rated to 2,200f. max working temp, you're not really getting them hotter than that are you?"

"Well Y E A H, mid orange isn't even general forging temp, I usually run in the mid yellow range." Funny coincidence I'd brought one of the 3,000f. split hard fire brick I was using for the forge floor with me so I got it out of the car to show them an honest to god, glassy vitrified, hard fire brick. "That's how hot my forge gets." I neglected to mention getting borax based welding flux on it a time or . .  two.:rolleyes:

Then they introduced me to Morgan ceramics, K-26 IFB and started talking about kiln washes to shield it from excessive temps. They warned me K-26 are only rated to 2,600f. with a safety margin but NOT that high. The next step hotter was a special order and cost more, of course. 

I just looked at Morgan Thermal Ceramics site for the next step hotter IFB's classification number, I didn't want to put wrong info out there if I could help it. Darn, I couldn't find anything about K-28(?) IFB but there's a new player on the site. TJM IFB!! The lowest classification is 2,750f. the highest 3,250f.! They have more alumina in the recipe too. 

I've got to call my guys tomorrow! IFBs that are proof against anything an air/propane burner can put out. The TJMs are advertised as flame face refractory and forges are listed. WooHoo! B) 

Morgan ceramics sells in Canada, it may be a hassle but you should be able to find the stuff. 

Frosty The Lucky.

 

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45 minutes ago, Frosty said:

Morgan ceramics sells in Canada, it may be a hassle but you should be able to find the stuff

I think I have seen those up here, if I build another brick forge I'll definitely look for those again.

It's sure is fun to see the look on peoples faces when you give them a good reference of the heat we're creating, a lot of people don't really get it when they think of hot steel by itself but their eyes really pop when you explain that your forge is hotter than is needed to cremate a dang body if built right ;) .

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  • 2 months later...

Welcome aboard Terrance, glad to have you.

Have you done a web search for Kast-O-Lite 30 li? Foundry Services and Supply makes it a bit of a chore to locate information but it's there if you hunt it out. It's listed under "Insulating Castable Refractories." 

I'll save you the hassle of hunting this time. 1 cu/ft requires 90lbs. 

I don't do the arithmetic.

Frosty The Lucky.

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Using an actual cement refractory coating over the ceramic wool blanket is a major factor in the eventual lifetime of the liner, and especially if you are using borax flux in the forge, as mentioned above. 

You can just get the wash and coat the rigidized blanket directly, but having just today put a fresh layer of cement liner in the floor of my forge, I observed CLEAR and DRASTIC differences between the blanket under unbroken refractory and what used to be the blanket under the cracks and holes the flux found it's way into.

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Kerry: NO refractory CEMENT, it will NOT LAST :( in fire contact. Use a proper water setting refractory, Glenn sells small quantities for reasonable. 

Frosty The Lucky. 

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