I'm new to fire bricks in gas forges. Is it normal for the brick under the burner to partially melt or vitrify. I got my forge used and the brick in question was already heat damaged and upon firing the forge for more than a few minutes it becomes tacky.

That sounds to me like someone used flux in it (borax).  That can melt/dissolve firebrick.   I use high-alumina kiln shelving in mine as a sacrificial base that can be removed and replaced when it has deteriorated enough.

That is a good possibility. Is there a trick to using flux around fire bricks without damaging them or is it just inevitable that they'll need to be replaced once and awhile?

Fire brick are a disposable item, but we can prolong their life by using a sacrificial barrier like kiln shelf to protect them

Note too that firebrick comes in a range of working temperature; without knowing the type it's sort of like saying: "Can I put 16 people in my vehicle?"

That's good to know. Unfortunately I know nothing about them other than they are fire brick but I'm strongly leaning towards them being the bottom shelf cheapies. They are the very porous gray ones if that really means anything. I have another one to use up once this one is to far gone then I'll see about getting some better ones. Thanks.

Edited January 1, 20224 yr by Mod30
Remove excessive quote.