what are you using for a furnace lid gasket???

My new furnace is all but done, but everything i have tried for lid gasket has failed, in super short order , What are you all using???

thanks in advance

V/r HT1

 

I'll go first. I dont use any gasket. I poured my lid on a good flat surface and let it dry out. Then I used it to level the top surface of the furnace body. The fit is good as long as I keep the top surface swept off. I'm not calling it a seal, but even at night I see very little flame leakage as long as my burner is turned correctly. Five years of use.

Pete

 

I made the lid hinge mechanism and cast the lid in place so it was a good fit when closed, over three years and one height extension later, it's no longer a tight fit. I may have to get some coarse silicon carbide and lap the lid to the furnace again. The refractory exposed to the flames in the chamber is taking damage but where the lid seals to the furnace wall is holding up quite well.

 

How much of a gap do you have?

 

A red c*nt hair in two places and in a 5 minute test it burnet the lid banding in those two places to carbon. I had a 2300 rated 1 inch ceramic rope gasket installed. It was glass. I’m trying to fit it out as Pete suggested since I could not locate anything rated higher.

FYI the new furnace is a beast! Twin 1.5 Moya’s with enough air to really feed them 166cfm. I maybe able to get the 35 minute bronze pours Mifco claims
V/r HT1

 

If it's that small get a pound of Satanite and paint the low spots. Fire it and repeat until sealed.

 

Propane for fuel is very hard to beat for furnace fuel.

 

My lid is convex in the center so it gets a pretty good seal sinking into the chamber. The top of the chamber is shelled-kaowool so it has give and conforms to the lid. I didn’t make it that way on purpose, it deformed when I welded the base of the lid to the walls which weren’t flat all the way around.

Lucky lol

 

No lid seal on mine. Seems flames like to escape out the gaps. I'm not sure if my vent would be big enough to let out all the gas if it couldn't leak. Between the lid and body.

Couldn't you just cast a Z shape into the top of furnace and bottom of lid to prevent flame escaping?

I did that on my ruby caster furnace body seems like it will work but haven't tried it yet.

 

I never used a lid seal either. The flame is not that big though and swirls just below and around the crucible. If needed a Z seal with some glass wool or ceramic blanket would be my preferred method.
I don't use a seal on my electric furnace as well as it sits pretty nicely on the body.

 

Here's how the pros seal their furnace lid at the 4:05 minute mark:

 

I've been experimenting some with waterglass. Could you paint some on the surfaces and get it just that c@nt hair closer? The stuff I have made does bubble up some when hit with a torch, I haven't let it sit until dry before torching, or tried a blow dryer before torching....

I also don't work with sh1t that melts kryptonite. ;-)

 

Here my furnace.

Under the lid I have a protrusion inside the furnace of about 1.5" which limits escaping gases between the body and lid. The Fermit (Satanite like substance) coating has broken off somewhat. It was painted over the Kaowool layer over the chicken gauze reinforcement, but I'll repaint it soon.