Seals better than copper...................................

 

If you are referring to Permatex, then only the copper RTV is for this application.
You may read the specification on the other Permatex products, such as gray, black, red.

 

Aren't they ALL for sealing?

 

hi temp permatex black rtv sealant is what i use. i wipe the joint clean after sliding the parts together and it looks fine.

 

If you do a little bit of research, then you can see that the "black RTV" is for automobile, and the max temp is 500F.
Here is the link: http://www.permatex.com/products/Aut...sket_Maker.htm

The Copper RTV is for motorcycle, and the max temp is 700F
Here is the link: http://www.permatex.com/products/mot...sket_Maker.htm
and Permatex even has a:
Suggested Applications: Exhaust header flanges, slip fit exhaust pipes, and mufflers

In this kind of application, we are making a gasket with an RTV sealant, and the copper has been designed by Permatex for motorcycle to withstand a higher temperature than the others.
I am not expert, but reading has given me this information.
Hope this help.

 

The cooper usually has the higher temp rating

 

I have started wrapping the pipe with a thin layer of glass wrap... then slip the tailpipe over the wrap. No mess, no cleanup later and very effective.

 

That's another interesting method.
By chance, you know what is the characteristics (flexibility, max temp.) of the glass wrap, and where do you get them?
I have to say that the RTV is kind a messy.
Thanks much in advanced for sharing the info.
Nick