Soft fire brick

[Jesse Latham]

Would there be any benefit from lining a forge ade from soft firebrick? Jess

 

[Stacy E. Apelt - Bladesmith]

I assume you mean - "....a forge made from soft firebrick".

Lining with kaowool probably would be overkill, but a 1/4" to 3/8" coating of satanite and a top coat of ITC-100 is needed for a working forge.

 

[Atlas Knife Company]

I'm curious as to why you say this, Stacy. Kaowool or Inswool will benefit from a lining of refractory, definitely, but IFB? While ITC-100 helps reduce gas usage, it certainly isn't necessary.

I have a customer with one of my forges that has been in regular use for over 3 year and the IFB have held up great and show no sign of needing replaced.

 

[Stacy E. Apelt - Bladesmith]

I didn't say it would burn up, just that a refractory layer and ITC-100 would be more efficient. Also, a full size forge operates slightly different than a smaller Atlas forge.

 

[Jesse Latham]

While this forge has not seen a lot of duty, it idles at 1500 deg with less than 2 lb of gas pressure. At full blast it tops out close to 2200 deg. It is using a venture type burner. My question was if something like ITC-100 would make it more efficient. There is about 4" of 2600 degree fire brick surrounding the fire box.

 

[Atlas Knife Company]

Yes, ITC-100 will make a difference. It reflects the IR heat back to the chamber. It's pretty expensive, though. You don't really have enough room for a thick layer of refractory, but ITC-100 can be real thin and still be effective.

I've spent a lot of time testing different designs to get the most out of a small burner. Burner placement and venting is crucial on a smaller chambered forge. A small vent, disguised as a pass-through, really helps the chamber fill with heat more evenly. On my forges, the small vent raises the temp of the back of the chamber by about 250° F.

 

[Jesse Latham]

Thank you for your replies. I will need to order some ITC-100. It looks like some experimenting is in order with the coating but more so for the venting at the back of the forge. Currently the chamber is 4.5 inches in dia, 13.5" long with 3.5" front and 2.5" back openings. I may open the front to 4.5". I made a plug to close the back opening but it sounds like I need to try different sizes of vents. I would think vent size would be relative to the temps I am trying to achieve. Interesting. Jess

 

[Stacy E. Apelt - Bladesmith]

When changing things, carry the front and back port down even to the forge floor. You want to be able to pass a long bar/blade in and out freely. On your forge I would put rectangular ports of 2X3 (horizontal) for the front and back.
A round chamber is very good. A round port and floor are not, because knives aren't round. The floor needs to be flat.
A 2.5" wide flat floor of bubble alumina or Mizzou is good. If you aren't ever going to weld in the forge, you can use satanite. That gives you about 3.5" clearance above the floor in your current setup once coated as below.

Basic procedure:
Wet the brick inside the forge
apply a sealer coat of 1/4" of satanite to coat the bricks
let dry for a day or two
fire it to cure
pour floor and cure for a few days
fire it to cure
then apply the ITC-100, let dry, and fire it.

This gives a 13.5" long by 4"/3.5" more-or-less ovoid chamber from your existing 4.5" round one. That works out to about 150 cu/in. This is a very good size for most all knife projects.The small floor still allows it to have a good swirl to the flames as well as ease of use at the ports.
With all the above, your forge should easily hit 2400°-2500°F with a venturi burner.

 

[TJ Smith]

I think if you are welding the flux would eat the soft brick.
Just finished my last build. I used koa wool, coated with ins-tuff,with a thin layer of furnace cement over it.Where the burner flame hits the wall I put a hard fire brick to stop any damage.
Gotta fire it up and see how it works.
Last forge I used koa wool and ins-tuff with a cat liter floor.If you are not going to weld works great.
My forge is vertical.

 

[Stacy E. Apelt - Bladesmith]

Please read the date on the thread before posting. Your information is hard to understand and not completely accurate, either. Probably a language barrier issue.

Thread closed.