I bought eight of these small bowls at the local recycle shop to use as small ingot moulds: anyone seen them before?. They were in a box with a similar quantity of similar size half height bowls that may have actually been the lids as well as small blocks of wood that may have been to rest the hot bowls on top of. They will obviously work for aluminium and bronze ingot moulds but would they work for iron too, if I coat with graphite?.
No teflon, just rough cast and blasted iron finish, with maybe some oil, just like a skillet. After finding out about perfluoroct-something or other, I'm glad I avoided ever using teflon pans.
Those are beauties. They may have been purchased as single-serve Dutch ovens for restaurant use? Even after they're well-seasoned I'd be alittle nervous about them capturing bronze or iron. Pete
So anything hotter than aluminium could be risky due to thermal shock, that hadn't occurred to me. They're an interesting item that probably was never used, a bit like fondue sets. At first I thought they were for baking pies although some restaurant specific use like Petee716 suggested is possible.
As far as thermal shock, they should always be preheated anyway as Jerry said. At least with angle iron trays you have some recourse if the ingot gets stuck. The first time I used my angle iron ones for bronze they all stuck, even with what I considered adequate oxidation. I had a bit of a circus getting them out which included a red hot forge, tapped bolt holes in the ingots, bolts, and a pry bar. They all popped eventually with minimal damage to the trays, but they're still functional. I lined them with petrobond the next couple times I used them with bronze. I use them bare-dog with aluminum. No problems. Pete
I have a rectangular steel ingot mould about 6" x 4" x3" with plenty of taper that sits out in the weather going rusty that I've used for iron without any issues: I did heat it up red hot before use but you can see from the iron ingot texture on the bottom that some rust flakes attached during use.
for some reason new ingot Molds seem to be "sticky" several ways to deal with it 1) Mold wash... dried this one should be obvious, if you are doing an alcohol based mold wash, spray them, burn them off, then preheat in the oven or on your furnace 2) soot them with an Oxy Acetylene torch 3) soot them zinc powder from brass or bronze melt , really just sit them over your vent once you start getting the zinc plumb , they will get a coating of white/yellow zinc powder ALWAY PREHEAT METAL INGOT MOLDS !!! One of you smart people with a degree in thermodynamics or sumsuch, can help here, but professional ingot molds are VERY heavy duty, like a full inch thick, I assume the large amount of metal works as a heat sink, and makes the ingots solidify quickly , casuing the ingots to pull away from the sides of the ingot mold , inshort freeing the ingots Mine are very similiar to Marks above, though with more draft, stuck ingots are very very bad V/r HT1
The more I look at these things the more I'm thinking of seasoning them with cooking oil and keeping them for baking meat pies.
They look like a potpourri bowl that I saw at the Dollar Store once....but they could be whatever you want them to be. They are pretty nice looking castings! We use Black Ice here to coat our ingots...which we call chill blocks...that do exactly as HT1 described..shrink up and pull away from the sides. They are on 1" pins that allow them to be rolled over and hit on the backside knocking out the ingots. We also use the Black Ice on furnace pouring spout...ladles pouring lip and around the autopour entry trough. It keeps the iron from sticking pretty nicely. If I can get a pic of the product in its packaging I will post it later.
Petee716 was right: tiny Dutch ovens, the lids were in the box with the bowls, though only four were left today:
That makes sense, it would be nice to solve the mystery of these things, a friend thinks he can vaguely recall a baked dessert dish in such a container. I feel like some primitive puzzling out an artifact not from my culture.
Mark I wondered if they would crack if used as a ingot mold so I found this video on youtube, have a look at 9: 46. Maybe a little preheat would stop the cracking?
I think based on that result (cracked iron) I'll keep them for cooking and rely on steel ingot moulds of the right size and shape.
An idea for ingot mo(u)ld wash: coat the inside of the mo(u)ld with linseed oil, then dust the oiled surface (liberally!) with powdered graphite. Toast over the furnace exhaust until the smoke subsides. This should act a bit like seasoning a griddle for the stove... I've got two small mo(u)lds I'm prepared to try this out on.