Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

To the brittleness issue..

You may be thinking of JB Weld Epoxy.  Look for JB Weld Sealant.

Just found a tube....
'JB Weld Ultimate Black RTV 100% Silicone Gasket Maker and Sealant'

The real deal.  Do not overuse it.  Neatness and cleanliness counts.
Wipe up after you are done.

Keep in mind, the only seal that counts is on the inside between the
glass tubing and the gasket material.  It alone bears the pressure.
Concentrate your energy there. 

Wayne