Framebuilders - Heat absorbing gels and clays

I've been looking at all of the nice work all of you folks do and I was just wondering why you guys don't use a heat absorbing gel or clay to localize the heat when brazing or welding.

You could weld/repair a dropout next to a brazed joint and not have to worry about it coming loose for example.

Just not needed? Never heard of it? I use it all the time in the automotive machining world.

There are gels that work so well,you can hold a wrench in your hand,run a 1/2" bead of gel around it and heat the end of the wrench white hot.

Needed for what? You give the example of adjacent brazing, might be an idea there, but it can be handled in normal course in part because the brazing materials often take more heat to loosen than to set in the first place. Might be an idea to localize paint damage or if one didn't know what alloy had been used in adjacent brazing, or knew it had been silver while one only had bronze on hand...

Other reasons why it may not be necessary is repairs vs. new building; fact that steel isolates heat fairly effectively anyway; structures don't normally have a lot of thermal mass (thin wall tubes etc....); bike makers are very careful for the most part to keep heat inputs very low...

Like my old Shogun touring bike,I don't what it was assembled with.I wanted to add a bunch of brazeons.Some went on the headtube,some on the fork crown,some by the seat stays,way above the bridge.

I'm used to using brass for cast iron repair,so I didn't have to worry about anything coming loose if it was hard soldered together.

No big deal,I was just wondering if it got used for building/repairing bicycles...guess not. Thanks!

Once you get decent torch technique, I don't think there are too many opportunities to use anything like that. People do use heat sinks. I'm trying to think if it would be useful to save some chrome on a repair, but I'm having trouble thinking of where it would work.