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I have a found object I want to use as a mold. I'm about 99% sure it's chrome because it's so shiny. Having learned my lesson about firing unknown metals inside the building, this one is on a hot grill outside. It's a gas grill and the temp gauge reads about 600. It has been in there for an hour and is only oxidizing a bit. I expected it to crack, flake or spall off the plated area (the desired effect). Starting to feel foolish that 600 is simply not enough heat to disrupt a plated finish or burn off any zinc-i-ness. Anyone venture a guess as to whether I'm wasting time and propane?

In a word - YES, I think you are wasting your time. I doubt that heating on a grill will cause the chrome plating to come off. I know of some home remedies that MIGHT work. Your best bet is sand blasting. That is the most sure fire way I can think of. There are other "old wive's tales" that soaking in household chemicals might work. For instance, my grandfather swore by Coca-Cola. He left things in a bath of Coke overnight and it took a lot of stuff off, including rust. Over cleaner has also been tried. A old time mechanic said that brake fluid would remove chrome and not to get it on chrome bumpers. Bleach may work.

The pros would use a much stronger chemical such as hydrochloric acid or even stronger. Muriatic acid is a weak solution of hydrochloric acid and you may get it at the hardware store. It's used for removing concrete stains, etc. It's pretty powerful and can cause severe burns.

Have you thought of making a rubber mold of the original and then doing lost wax casting to create a plaster-silica mold?

I started to feel kinda foolish and pulled it out to cool. I'll sandblast it instead.
Would really like to know how it holds up in real heat so I may have my husband drag the smaller kiln outside tonight.

Am really curious as to how dense the plating really is (IF it's chrome). In regular zinc-galvanized items like steel pipes, I have always assumed the zinc is a thin coating that can be burned off as a gas. It's all guesswork on my part; and a miracle I haven't asphyxiated myself by now.

I agree with Jeff, for what it's worth. Deplating can be done in jeweler's pickle with electrodes but I've never done it, not sure how. But shiny isn't always an indication of plating; I've got some stainless steel that looks like chrome and I know it's not.

If the shape's that great I'd take it through the kiln and see how it holds up (with plenty of ventilation). Otherwise, you can always make a master mold from it and do it in clay or refractory plaster....

Not to ask a stupid question, but you're sure it's not aluminum, right? If it is, that would be a nasty surprise around 1000 degrees.

i am a big fan of either using a torch or a bonfire. rosanna aka ms pyro

I'm certain Judd. It has held up to a gas grill, a MAPP torch and firing at 1400. It's a way cool piece of stainless in a killer shape. (Goodwill $2.50)