Jim,

We need more info - what are you fusing, what temps do you need to achieve and what level of accuracy/control is necessary? Not sure what you mean by a goosenecked fire pipe, either.

Propane burners come in a few different configurations and you might want to look at Michael Potter's book on Forge burners for some guidance.

You say heat sink capability - a heat sink pulls heat away from something else. Ideal materials are silver and copper, if that's really what you want. If you actually want insulating capability then I'd suggest something like ceramic chips, grog, alumina frit, pumice etc. The ceramic chip would have the least issues with creating dust and contaminants.

If you can tell me more about what you intend to fuse and what you're trying to achieve I might be able to offer more suggestions.

Rich

Can't offer refactory comments. However if your kiln will have a sheet metal case, you need a to break form the sheet metal, and do not have access to a box break . You could easily fabricate a finger break jig from angle Iron. this will allow you to use a hammer to form really neat, accurate corner breaks. If interested I can describe the process in more detail.