What do I use to mark a cast iron part that gets very hot?

The only thing I've ever found that would cut cast iron is an abrasion wheel (or friction wheel). About four years back I remodeled a bathroom that had a cast iron pipe sticking up abnormally high with an old toilet. When I replaced the toilet it would not sit on the floor because of the cast pipe. So I figured out how to cut it. The job wasn't easy either. I used a Dremmel and a friction wheel to score the pipe along the inside to the point where I could break the rest of the pipe off down to that score line. Prior to that I tried a hack saw - wouldn't do a thing. I suppose I could have gotten a carbide incrusted blade - that MIGHT have worked, but because I already had the Dremmel and the wheels (and I used a lot of them) I went ahead and cut it that way. I suppose I could have cut completely through if I wanted to spend the time and energy doing that.

As for the first answer telling you that "Only a manufacturer can change the surface" is bull. Cast iron is brittle and can be snapped like glass. It's very hard to do but that's basically how a soil pipe cutter works. (Soil pipe is what the toilet drain is called)

Hope this helps.

'')

I used a wad soaked with an acid to identify the part with ferric oxide.

Cast iron is cast iron and only a manufacturer can change the surface.

Plus, cast iron gets hot - that's the glory of it.

Make a small cut with a hacksaw

have you tried hi-temp paint? they sell it at automotive stores. used to paint cast iron engine blocks and heads.

Soapstone marker like welders use.

Check it out:

Harbor Freight: http://www.harborfreight.com/4-piece-soapstone-mar...

Amazon: http://www.amazon.com/Soapstone-Marker-Welders-Tex...

Welders use these things to make marks on metals that won't burn off. Grab one and you're off to the races.