I'm using an 8x10 enlarger for the first time. I cleaned the glass negative carrier with Windex and PEC lintless pads but it came out with smears and smudges, even after multiple cleanings.
I'm not sure if this is some old greasy stuff on the glass or some residue from the Windex.
Just been cleaning a lot of glass, first I use warm washing powder, the biological variety for clothes, followed by a good rinse in warm water. Final clean is with "Screen wash" used for car windscreens, this always seems to leave no marks, and very clean glass.
Some things just can't be cleaned that way. I have a Fuji Finescan 5000 with a 13x18 piece of coated optical glass in it. Fuji recommended using a soft cotton cloth that had been laundered many times but dried without fabric softners. They use Zeiss lens cleaner with the cloth and said it's the best cleaner on the market in their opinion. I use this on lenses, scanner and the coated glass in my Durst glass carrier.
Most enlarger carrier glass isn't coated, and even coated glass will stand up to a good non abrasive washing. I would normally recommend Nilglas it's a UK trade product used for cleaning glass. It is excellent for cleaning optical glass and removed years of grime safely from a coated Dagor lens I bought 2 or 3 years ago.
I just bought an old Federal enlarger that had not been used for years, the plastic power cord had melted to the enlarger lamp houseing, the glass for negative carrier was very dirty with a thick coating of grim. I soaked the glass overnight in bucket of warm water with couple of drops of dish soap, then just a rinse in distilled water.
I tried this method mentioned in this PDF, that is, I placed my 8x10 glass in an 11x14 tray and filled it with Windex and let it soak. I still had streaks, but you might have better luck.