Is there any clay to insulate the heat?

[Caballo bueno]

I have to weld a thin piece in the forging and I have a problem,
 a part that goes behind the welded piece is very stuck and it will also take a lot of heat,
 it may even burn.
 Is there any material with which to coat this part
 and protect it from heat to what does not burn?

Edited November 24, 2021 by Mod30
correct type size

[Charles R. Stevens]

Depends on the part, we’re it is in relation to the what and how much room you have to work. 
a wet cotton rag might work, ceramic wool insulation might work, a big mud pie. Depends on the small details 

[Steve Sells]

If you learn how to forge weld it should not burn unless you are using an odd combination of steels

[Caballo bueno]

It is a hinge that I have to weld for an implement but the part where the pin goes I do not need to reach that temperature I only need that temperature a few millimeters back and since it is millimeters and the part that does not have to be welded is finer it can burn Would fireclay work?

[anvil]

The little butterfly hinge is forge welded. Coat you work with a good layer of experience, and no problem. The best way to get it is to do it.  Have fun

[Irondragon Forge ClayWorks]

Fire clay should work just fine.

[anvil]

Do you think that fire clay might contaminate the weld?  

Fire control, a slow rising fire, and a way to apply a bit of water to just the barrel. Think an old fashioned hand oiler.

Also, there is no reason you can't get the barrel hot, even up to a forge welding heat. Just don't burn it. Thus proper fire control

[Caballo bueno]

is to weld a piece that is finished and I have to avoid those high temperatures
where it is not necessary
to make it as clean and smooth as possible

Edited December 4, 2021 by Mod30
Text size corrected

[anvil]

To be clear, if you do a forge weld close to a finished part, no matter what you do, it will get hot. As long as you dont burn it, you will have no problem. Anything you use to protect the finished part may contaminate your forge weld. Thus, bring your forge weld up to a non sparking heat and you will be ok.

Heres an example. A number of leaf and tendril details to be forge welded together. All leaf and tendril are finished. Then forgewelded and no to little changes made to the original pieces. I know you said small pieces, but the principal is the same. I can show you a pic of them in the fire if needed. This detail is actually forge welded again onto a picket. So it is a completed detail, leaf and tendril, FW onto the picket. 

[Frosty]

Forge the section thin AFTER you finish with the welding. A good rule of thumb is, "work thick to thin." Meaning do the heavy forging first and leave the thin parts to the last. If you forge thin parts first they are much more likely to burn or melt when you forge thicker sections.

Make sense?

Frosty The Lucky

[Caballo bueno]

Good job It's incredible. Thank you boys!