Please Close The Gate Signs: Paint Masking FAIL

A warm day let me shoot the engraved signs for the Vassar Community Garden gates with rattlecan black:

The full sheet of orange acrylic arrived with plastic protective film on both sides, which I planned to use for paint masking. Alas, one side also had a wrinkle running its length that ended up on two signs, so I replaced that film with blue masking tape.

As fate would have it, the first side of the first sign I peeled had masking tape and produced what you see above.

Things went bad in a hurry. The paint had no adhesion whatsoever to the plastic film and fell off in flakes as I peeled the film away:

I assumed the flakes would just fall off the signs, perhaps with a little persuasion, so I peeled and weeded all the signs before cleaning them up.

Although the paint was fully dry, when the molecularly smooth surface of each paint flake touched the molecularly smooth surface of the newly exposed acrylic, the two instantly and permanently fused together.

There were a lot of flakes:

Removal techniques that did not work:

• Vacuuming with a brush
• Gentle rubbing with a soft cloth
• Firm rubbing after spraying with acrylic cleaner
• Scraping with a plastic razor blade

So I deployed a P220 grit sanding block and wrecked the glossy surface of both sides of all six signs. I briefly considered trying to recover the finish by sanding them all up through about 2000 grit, then came to my senses: my sanding arm is weak.

Careful examination of the last picture shows several places around edges of the circle where the plastic film melted into a blob that blocked the paint, rather than vaporizing. I used enough power to engrave only about 0.3 mm deep (because they’re engraved on both sides), but the transition wasn’t fast enough for a clean edge.

They don’t look as nice as I’d like, but they’re good enough for the purpose:

The acrylic sheet is more see-through than I expected, at least when backlit by bright sunlight.

Next: we discover what happens to UV-stabilized orange acrylic and black outdoor paint over the course of a year in garden sunshine.