You can order First contact from ROb Stanwax (www.stanwax.co.uk) here is the link:
http://shop.stanwaxlaser.co.uk/first...iclean-1-p.asp
There you go, just apply with the nailpolish-like brush, leave to dry for at least 20min, carefully take of and be amazed!
They did a test once where they let someone clean there glass or a lens as clean as possible, then put on First contact like a letter D.
Let it to dry and then take if off, you could clearly see a letter D where the glass or lens was cleaner then the stuff around it.
Hence they called it the D-Test (and my first name has nothing to do with this!!!).
So yes dirty windows (from Smoke fluid !!!) can really destroy your output powers. I have seen dirty mirrors and dichro's account to a loss up to 250mW in total on my 1.8W projector!
So maybe not 50% but a helluva lot !
I didn't fail !
I just found out 10,000 ways that didn't work.