Residue on smooth sheet, not soluable to soap and water or alcohol.
I have printed maybe a half a roll of prusament pla with my new mk3s and suddently had problem with the first layer not sticking. I've been cleaning the smooth sheet with 94% ethanol. When looking closely from an angle, I can see grease-like residue (like residue of fingerprints) and "shadows" of the printed parts on the bed that does not dissolve to alcohol or water and dish soap.
I turned to the sheet around and all is well again. Should I try acetone or maybe the dry sponge as per prusa knowledge base? This is the ethanol I used. https://images.obi.at/PROD/DE/document/344/344724_datasheet_1.pdf
Before having at it with acetone, (which can be hard on the surface coating and damage it), try simple dish soap and hot water. Preferably unscented dish soap. This is generally considered the best de-greaser for the sheets. And it's cheap and common to get. Ethanol works OK for in between washings. Maybe every couple of prints in a row I use ethanol to clean. But eventually I go back to soap and water for a real clean and de-greasing.
That said, as you use your printer, the sheet will eventually start to show marks from printed items. These things are a long term consumable - but consumable none the less. You might find in a year or so that a quick wipe with acetone might be needed if the hot soapy water stops working. But don't be in a big hurry to reach for acetone.
Thank you for your reply.
I find it odd, that this residue is not removeable with soap or alcohol. It almost seems like that the and/or heat has with some starange way like "burned" the grease of the fingers to the bed. I have never seen this with alcohol when used as a cleaner.
Anyway, it could be that the affected surface is fine after dish soap cleaning and the marks are only cosmetic. In any case I'm now using the other side with great success and try hard not to leave any fingerprints to the bed and do the cleaning only with dish soap and water.