helium super leak fix?

[tope]

I have a helium super leak that is too small to locate. Someone suggested coating all the connections with the brand name Estane polyurethane. You mix 10 g Estane with 50 g methylene chloride and 50 g acetone and paint the solution on the suspected leak areas. Has anyone tried fixing a very small vacuum leak in this manner?

 

[sciguyjim]

Hi, I'm not familiar with your chemicals, but when I worked with high vac systems we did on occasion spray suspected couplings with some kind of aerosol product that dried to a continuous film. Watch your pressure as you do it. You may locate the leak this way. We also used volatile solvents and even butane gas as markers that could get pulled in through the leak as a means of locating them. Once I enclosed our electron microscope in plastic bags and introduced butane to check that there really was a leak somewhere (He leak detectors are very sensitive to butane.) There was no reaction, so the prob may have been in the vac gauge electronics.