Problem with Plexiglas

[Jeff Belany]

I have been making quite a few night lights lately and have had very little issues. But, for the last dozen or so I have been getting residue on the engraved side that is almost impossible to clean off. I tried with and without the paper backing. The oddest thing is that some on the same sheet are OK while others have smudges. Anyone have any special cleaning techniques or cleaning products to recommend. I had always just used glass cleaner in the past.

The reality is that when these are on the floor in use, the small smudges will never be seen but you can't tell the customer that when they are holding them a foot from their face and aren't very happy. I tried a couple quick pix but they didn't really show the problem.

Any ideas are welcome. This forum is the best!

Jeff in northern Wisconsin

[Joe Pelonio]

Try spraying with window cleaner before engraving, perhaps the Sprayway aerosol from Costco. i don't engrave with the paper on, if the first pass doesn't penetrate well you have adhesive left and have to run a second pass.

The best cleaner I found is Rapidremover, a citrus based adhesive remover for the vinyl sign industry.

[Dee Gallo]

I always remove the paper from the top side and just leave it on the bottom to help with cutting flashback. After engraving, I rub with a washcloth and rubbing alcohol, then rinse in water and dry with a towel or microcloth... never had a problem with smudges after that. Are you using air assist? I always do and it helps with sooty residue. Are these smudges from your fingers? Are they there before you engrave? Maybe your paper backing has left some glue behind? Just guessing here, but you should be able to clean them up and should... I know that the first thing people do is hold the piece up to the light. I usually take them into a dark spot and show them how they will look, so they are happy. People have no imagination. You might devise a "display box", which will provide a dark place for them to see the effect.

cheers, dee

[Jim Reinhard]

I use novus 1 to clean and 2and 3 to remove light scratches

[John Noell]

If a quick wipe with window cleaner does not do it, we use Novus 1. A bit more work but does the job.

[Jeff Belany]

I do use air assist, I've tried with and wthout the paper. The last ones without paper were the worst ones yet. I really thought it was adhesive residue from the paper but it is obviously something else.

Dee, how do you get away with the alcohol? When I use it a get the tiny cracks on the edges. Maybe washing them right away does it? I'll have to try that.

I'm going to try some plastic polish. Maybe even my Beall buffing wheels.

Thanks for the in[ut.

Jeff in northern Wisconsin

[Richard Rumancik]

Jeff, I can't say what is causing the smudges you are seeing. But as far as cleaning acrylic, if you read the archives, you will find that there are a lot of different opinions as to what to use. However, it is best to know the brand/grade of material you are using and see the manufacturer's recomendations. Some acrylics will tolerate alcohols, to some degree, while others can't. As well, "rubbing alcohol" sold at a drugstore can vary quite a bit as far as water/alcohol ratio and in chemical composition. It could be 70% to 99% alcohol by volume and could be isopropyl alcohol or ethanol. It can vary in different countries as well. In my opinion even 70% alcohol is probably too strong.

Now as far as "window cleaner". When people say window cleaner, I usually assume ammonia based, which will attack some acrylics. I am sure there are non-ammonia based window cleaners but when someone says to use "window cleaner" be careful. Again, look at the data sheet from the manufacturer. Don't assume what works for one of us will work for you, as we don't know what acrylic, window cleaner, or rubbbing alcohol you have on hand.

Also, many chemicals will attack at edges of holes and edges of sheets, but won't cause a problem in the middle of a sheet. So it also depends on how/where it is applied.

You could consider trying naphtha and see what it does. Again, check the data sheet of the acrylic. Naphtha is available from paint stores. Coleman camp fuel, which I use, is very similar to VM&P naphtha and may be easier to find.

[Shawn Handley]

I think I should chime in here. There are basically 2 types of acrylic. Cast and extruded. One is generally more expensive than the other and I'm afraid I don't remember which was which. When I was cutting the cheaper acrylic, I was getting the residue smudges you are talking about. The best I could do was to run 2 passes without any paper or film covers with the acrylic lifted up 1 or 2 inches. I'm sorry, I do not remember which one was the cheaper one but when I cut into the more expensive acrylic, I got waaay better results.

One quick mention is that I also used a citrus cleaner by 3M called "3M Citrus Base Cleaner" go figure) before I cut and RIGHT after I cut. I mean as soon as the head pulled away, I was in the machine wiping it with a wet soft towel (Do not use paper towel. It scratches). That helped with the cheap stuff and residue.

I also used alcohol to clean my pieces. It didn't help with the residue. Man, that was some crazy crazing on the cheap stuff. The more expensive stuff didn't seem to do anything with 99% isopropyl.

My experiences may differ from others.

EDIT!!!!

I forgot!! I was able to remove the really bad smudges from residue with a small torch lighter to smooth it out. It worked great!

[Mike Null]

I use denatured alcohol to clean cast acrylic but extruded will craze when using alcohol.