Washing protective coating off acrylic?


#1

Has anyone found a method for removing the protective coating easily? I just received an order for 140 pieces of acrylic, each of which will have something like 20 bits of protective coating on one side. Just wondering if anyone’s found a method or chemical bath that will wash away the bits without damaging the acrylic.


#2

I always remove the protective layer before cutting/engraving. Leaving it there will have poor results.


#3

Soaking in alcohol hand cleaner or denatured alcohol can dissolve most adhesives used for tape or other coating with adhesive backing.


#4

Don’t you get any burn marks?


#5

Not sure whether you were talking about Proofgrade or other acrylic. A lot of places use a plastic coating that creates a mess when engraved. Haven’t really used the Proofgrade for anything but cutting so I don’t really know if their masking is best on or off for engraves. For cuts, I’m not sure it matters. I haven’t had problems with burn on the acrylic. But others have used it far more. Will let them recommend.


#6

Take off the plastic coating and replace with paper transfer tape…no burn marks if your settings are right…


#7

Alcohol will cause crazing on acrylic.


#8

Could you be specific - which alcohol and which acrylic ?
As an ex-industrial chemist with ICI who produced the original perspex, aka poly methyl methacrylate, I’ve never come across either methyl, ethyl, or propyl alcohols affecting the surface of Perpex,. so I suspect that Lucite and Plexiglass, the American equivalents will be equally unaffected.
Regards,
John :upside_down_face:


#9

No, I can’t! I’ve read numerous times on the internet that it does and was trying to be helpful. As you know better, great! Glad to know the truth!


#10

I hope you didn’t take in any way as a put down, as it may be that the difference in our two versions of the English language (:wink:) across the pond, may name something as ‘alcohol’ in the US, but that contains other solvents. so I thought it best to explore the possibilities, so we can give other peeps the best advice.
Regards
John :upside_down_face:


#11

No worries! I saw your credentials and knew you know better!

:slight_smile:


#12

It may be that some denatured alcohol could have many odd toluenes or similar cyclic structures in some brands or times just to poison folk who would drink it. I do not know what adventures the UK has had with blue noses and tax folk over ethanol but it has been quite weird over here.


#13

I’ve noticed a difference between the 70% isopropyl and the 91% here in the US. The cheaper 70% causes crazing in the 91% does not on most of the acrylics I’ve used it on.


#14

Good catch.
I wonder if there is something nasty there as well as water in that unlisted 30% ?
It oxidizes to acetone, which will attack acrylics, so there may some of that present.

I expect it’s the same in the US, but in the UK, you will find a big difference in the purity of chemicals when you go from lab. grade to technical grade, and this reflects in the price. If it’s cheaper, then it’s probably not so pure, and might be cut with anything !
:upside_down_face:


#15

At work we have a 55 gallon drum of medical grade isopropyl, 99% ethanol iirc. Most people are going to just use what is in their bathroom, that bottle of 70% isopropyl from the drug store. Who knows what’s in the other 30%.