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View Full Version : duraboard vs insboard


Eric Covington
12-31-2011, 09:52 PM
I am building a 80 lb wire melter.

Does anyone have any opinion in using one product vs the other (same max temp ratings for both)

Pete VanderLaan
01-01-2012, 08:26 AM
I'm familiar with Insblock ( AP Green) and with the higher temp white board we usually call M board from Thermal Ceramics. Insblock is rated at 1900F max, turns punky if you actually go anywhere near there, is acrid while burning off. It's OK on the outside of a furnace . The M board has a far higher rating (2300F) but has gotten to be seriously expensive at about $9.00 per sq ft. It works great but you really should put it where it belongs. I use it in annealers and slumping kilns.

You can make your own block insulation with a shovelful of cement, one of ball clay and about ten of vermiculite. Mix it dry, then add water to taste and cast it in place. It works very well. You can usually get the vermiculite at a big greenhouse.

Eric Covington
01-01-2012, 12:23 PM
I am looking at Insboard 2600 HD and 3000

e.g. http://www.wardburner.com/images/INSBOARD26_data.pdf

and Duraboard 2600 and 3000

The numbers in both cases refer to their max working temps.

I am assuming this is not the product you used. Am I correct in this assumption, please let me know.

Do you have any idea of what the thermal conductivity is of the home made material you suggested?

Thanks for your input,

Eric

Pete VanderLaan
01-01-2012, 04:00 PM
I don't think either board you mention will hold up long in a hotface. Once the binder burns out, you just have straight alumina silicate fiber totally softened as if rotted. Your hotface in a wire furnace should be brick in my opinion. I would suggest 2600F IFB. Otherwise it's going to get punky pretty fast. You could back the brick with rammable fiber. I like the lubed stuff.

The material I refer to is commonly called block insulation and is an outer castable to retain heat. It would not do well in hotface. You can buy block mix, or make it.

Scott Dunahee
01-02-2012, 09:23 AM
I ran a wire melter for almost 10 years. I'd advise k-2800s for the inner hot face. The shelves you cut into the 2600's get pretty fragile after a couple of coil sets. the 2800's last longer.

I never replaced my fiber insulation at all. I'd pull my unmortared liner bricks out and put the new ones on place. the fiber stayed and looked fine so I kept it.

Cheers in 2012.

BSD

Jon Myers
01-02-2012, 03:17 PM
I'm familiar with Insblock ( AP Green) and with the higher temp white board we usually call M board from Thermal Ceramics. Insblock is rated at 1900F max, turns punky if you actually go anywhere near there, is acrid while burning off. It's OK on the outside of a furnace . The M board has a far higher rating (2300F) but has gotten to be seriously expensive at about $9.00 per sq ft. It works great but you really should put it where it belongs. I use it in annealers and slumping kilns.

You can make your own block insulation with a shovelful of cement, one of ball clay and about ten of vermiculite. Mix it dry, then add water to taste and cast it in place. It works very well. You can usually get the vermiculite at a big greenhouse.

So you are using plain Portland cement and ball clay like OM4? I've often wondered what it took to get something that would take backup liner temps.

Pete VanderLaan
01-02-2012, 10:11 PM
That would work fine. The way we mixed it was to put a big sheet of plastic on the floor big as in 15x15 feet, dump all the materials you want into the center and dry mix slightly. Then add water and just grab the corners with a few friends and just roll it around. It's just a great way to mix castables.

Take the mix and pack it in place with your hands and then trowel the outside smooth. Use a squeegee bottle of water to bring up the fines. You can play with the proportions. I used it and it insulated really well, got rock hard and lasts forever.

Franklin Sankar
01-04-2012, 06:38 AM
Is there a substitute for Ball clay? eg Terracotta? why Do I ask ...because "ball clays are rather rare in the world" at least in my part of the world.
I wont ask about the substitute for Friends. ;)
How about......."Use a squeegee bottle of water to bring up the fines."???
How??
Franklin

Pete VanderLaan
01-04-2012, 08:39 AM
Terracota is too vague a term for me but those are earthenware clays and should work fine. Just try it. It's an insulator, not a hotface.

Franklin Sankar
01-04-2012, 12:31 PM
Thanks Pete and the fines raising up????
Franklin

Pete VanderLaan
01-04-2012, 03:53 PM
Sometimes you just gotta try it Franklin.

Dave Bross
01-04-2012, 09:50 PM
Franklin,

Talk to someone there who does concrete work. driveways and sidewalks are finished with a similar technique.

The more you run a trowel or smooth surface over something like that the more fine stuff floats to the top and makes a nice surface.

Vermiculite fails around 8-900 F. So does the cement. Be sure you've got enough insulation inside the block mix to stay well below those temps.

Pete VanderLaan
01-05-2012, 04:28 AM
Vermiculite works a lot hotter than 900F. I used it an an annealer floor for a long time. It is not a hotface material in a furnace though. I used to put that mix on top of mizzou on furnace crowns and never had any problems with it.

Dave Bross
01-05-2012, 06:17 AM
That's good to know. Real life experience trumps what you might have read.

Franklin Sankar
01-05-2012, 07:12 AM
Thanks Dave this clears up a whole lot of casting issues you all were talking about in the past .
Pete I remember when you all were saying that the pot would float up when casting it in the furnace, I was amazed that it could happen. I could not believe the density was so different. Its good to know.
Franklin

Pete VanderLaan
01-05-2012, 08:37 AM
Aircraft carriers can float, why not glass crucibles. Crucibles with holes in them, now that's a different story. Submercrucibles?