<p>I have started printing about a month ago on an Ender 5 (using mostly PLA but recently also PETG) and it seems it's about time to give the print bed a more thorough cleaning than what I usually do after most prints. I'm using the flexible magnetic mat that came with the printer which has a slightly rough surface, but all of the cleaning suggestions I found so far either did not mention the bed material or were specifically for glass beds.</p>

<p>Can/should I use stuff like acetone or rubbing alcohol on this? Or should I stick to warm soap water?
I have had some fairly decent results with spectacle cleaning tissues but that will only remove grease, not filament residue.</p>

<p>Also, I am occasionally having some first layer adhesion issues (especially with the PETG or when printing things with a circular base) and I was wondering whether common suggestions like glue sticks or hairspray to prepare the bed for printing  can also be applied to the flex mat?</p>

I have the WhamBam system which uses a PEX layer over flex steel (which sticks to a magnetic sheet on the printer bed). To clean old material off, I use a "brass sponge" intended for cleaning soldering iron tips to remove the old plastic, then give it a wipe with a paper towel with some isopropyl alchohol (I have 99.99 anhydrous on hand as I use that for cleaning printed circuit boards as well).
The brass sponge is fairly soft, does a good job of grabbing the old plastic without tearing up the PEX layer.