I just started using lapping films. I was making great progress and then BAM a scratch. I had to go back from the .5 micon tape to the 1500 diamond stone to get it out. I am guessing it was some stray piece of metal or grit that landed on the tape? Anyhow I have started to cover my lap paddles in the bags they came with. But it occurred to me that I could clean the tape right before use. I started using a soft eraser but then notice that some wash or wet wipe the tape?
Do any of you clean your tape or film and if so how?
Bob you may also want to clean the glass surface on your lapping film paddles, (or what ever type of paddle you are using with the films) before applying a new piece of lapping film, and clean your hands first also, to prevent cross contamination. I have had a piece of some sort of contaminating particle get stuck between the film and the glass right in the middle of the trail the film follows up across the knife metal. With every stroke, I felt the bump, rendering that piece of film useless. After removing that piece of film cleaning my glass and hands, and replacing the film all was fine again.
To answer your specific question, like TC suggested , I too do clean my used lapping films with Isopropyl Rubbing Alcohol applied to a soft towel in between film grit changes while using them in a normal sharpening progression.
I use a Scott shop towel which is pretty tough and I’ve never noticed any build-up of residue, probably because I don’t scrub the film with the towel. It’s only used to absorb the excess liquid. One wipe and it’s done.