I’ve just been trying to clean of a little smoke residue from around the edge of a piece of acrylic with what is marketed as denatured alcohol - a fairly innocuous solvent - using a cotton bud.
The result is a series of cracks, up to 1/2" long at random intervals running perpendicularly into the acrylic.
I suspect that this is an effect that I first came across about 50 years ago, where a solvent that does not normally affect a particular plastic, will do so, if the plastic is being stressed in some other way. An example I’ve given elsewhere on the forum was the combined effect of heat and mineral spirits on rigid PU foam.
In this case, I’m guessing that the molten surface of the laser cut edge has mechanical stresses locked into it, and these are points of attack by the solvent.
I’ve repeated the process on the scrap that I cut off, and that, too, produces the cracking. However, swabbed onto the flat surface, or onto a sawn edge has no effect.
Anyone care to add thoughts or experience. please come on in.
Although the cracking is randomly appearing around the cut edge, not completely random. It always starts from a small ‘pit’ on the underside of the cut surface, where, I guess, there has been some flashback from the honeycomb.
I stripped the plastic masking off the surface, both top and bottom, so I’ll do a follow up experiment with a paper mask stuck on the lower surface, in the next few days.