Resin stuck to FEP

[Helotech]

So, I think I ruined the original tank film after I finished my 2nd print ever.
Thankfully I had ordered 2 spare aluminum resin tanks so can continue printing until I order more film.

When I cleaned out the the tank, I was very careful. After emptying resin back into bottle, I used alcohol and gentle dabbing with paper towel and microfiber cloth to sop up the residue.

I noticed there were 2 or 3 spots of harder resin, a couple millimeters across, stuck to the film. I sprayed in some alcohol, and gently used the plastic scraper to try and pop off the resin. No joy. Wasn't budging.

More alcohol and gentle rubbing with microfibre cloth. Nada.

I placed the tank on a paper towel and tried to gently scrape off the residue with a finger nail (wearing gloves of course). Still not coming off.

Of course, I thought youtube would be my friend. I saw a video of someone gently pushing on the back of the FEP while scraping with finger nail. I tried this and nothing.

After more alcohol wiping I noticed there are now slightly larger white marks where the original stuck resin was.
As I turned the tank in the light to see what was up, I noticed the FEP had a wavy appearance around the white marks. You can't feel it, but it is there.

I'm thinking I may have "stressed" the FEP, and the white marks may have come from me damaging the FEP with pressure between my finger on back of FEP and nail on front trying to scrape it off. Kind of like bending plastic from packaging back and forth and causing a white seam. Make sense?

Anyways,

How do I avoid this in the future.

Thanks

[cliffyk]

Replace the FEP, sounds like you're on that path already. FWIW I've never had resin stick to the film so tightly that a bare fingernail¹ would not pop it off.

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¹ - This stuff is not THAT toxic--if it were they'd not be allowed to sell it to regular happy-homeowner consumers.