When you get a pack of bolts/screws with certain mechanical products sometimes the threads come with a pre-applied thread lock (usually blue in colour) - I'm thinking more mountain bike stuff actually as this is where I recall seeing it.

What is the product applied? Normal Loctite solution etc seems too thin, this stuff is more like a thick paint.

http://www.threadlocking.co.uk/pre-applied-products.html

"Normal"Locite comes in different grades to suit the pitch of the thread and job in hand so an optical technician uses a much less viscous grade than an industrial pipe fitter.

[Edited on 13/7/13 by britishtrident]