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Scott Shepherd
12-12-2007, 4:37 PM
I've been piddling with some cast acrylic and I'm not having the best of results and thought someone here would know the fix because I burn up all my material. When I am engraving text on the stuff, it seems that a smoke like residue is around the area engraved and it won't wipe off. It's not a residue as much, but it's very similar to the smoke damage/residue you can sometimes get with too much power on a plastic like Rowmark.

I've tried going way way down on power, up on speed, up on power, down on speed, up on speed, down on power, down on speed, down on power (you getting the picture?).

Any tips on getting a nice clean job? I currently have it minimized to where no one has noticed it, but I can still see traces of it and I'd like to wipe it out completely if possible.

Any tips?

Todd Schwartz
12-12-2007, 5:34 PM
Scott - I have found that the cast that I get from Home Depot did this. Both around the engraving and cut lines. As you mentioned, you can minimize it, but looking at it with a critical eye, you will still see it. No amount of power/speed/DPI/PPI/masking adjustments worked. Went to a local plastics dealer, bought their cast and have not had this issue.

I know this is not a lot of help, but you are not alone in this battle.

Todd

Barb Macdonald
12-12-2007, 5:41 PM
for deep engraving, but depending on the intricacy of the graphics, "weeding" can be a pain. Two passes works well for smaller stuff, and for sure we always try to remember (!) to use bottom-up engraving, because of the debris build-up. Larger graphics aren't really any better or easier, in my opinion. We have a epilog 60 watt, can't remember the settings, stuff is at work, but the settings could be in the PDF available for the machine on their web-site. The haze can be from heat "washing" over the edge of the graphic, which is when two passes helps us.

Most people don't have sign-makers' (i.e. perfectionist) eyes, always looking for the flaw. But that's when the REALLY picky customer shows up:), just to keep us on our toes.
To the Creek!

Frank Corker
12-12-2007, 6:57 PM
The easiest thing is to use nail varnish remover. That's what I use most of the time .... can't figure out why my wife gets so upset... anyway, removes the debris that sticks to the surface and also removes the cutting marks. Have still to find something better.

Lisa Walter
12-12-2007, 7:20 PM
I am new to this........but I had a problem similar to this last week when I didn't turn my air assist on. As soon as I turned that on (I already had the blower on) it stopped.

Mike Null
12-12-2007, 7:31 PM
I usually engrave mine with the paper on but Novus polish will remove the residue. Use NO. 2 then No.1

I do quite a few and it isn't a serious problem.

James Rambo
12-12-2007, 7:34 PM
I use the cheap acrylic from HD at time . When I raster it has a haze around it and I use NOVUS 2 fine scratch remover and it works very well. I got it from laserbits.

Scott Shepherd
12-12-2007, 7:40 PM
I was trying to avoid using Novus #2 (or any Novus products due to the fact I don't wish to sit and clean every item). One shape I did had about 50 little 1/8" squares all right next to each other. The Novus #2 gets all down in those areas and I can't get it out without doing some serious handling (which is what I plan to avoid).

My cast came from a plastic supplier as well, not HD. I also had the same problem with air assist on as off.

Guess I'll have to try the nail polish remover trick.

Kim Uleberg
12-13-2007, 7:15 AM
I donno if this is the same problem. But I used to have problems with engraving on acrylics, the engraving was never smooth and the edges had residue that i had to scrape off, which often left marks. When we put the laser around 1,2 - 1,5 out of focus everything went really smooth...no residue at all.

Ed Newbold
12-13-2007, 7:25 AM
The easiest thing is to use nail varnish remover. That's what I use most of the time .... can't figure out why my wife gets so upset... anyway, removes the debris that sticks to the surface and also removes the cutting marks. Have still to find something better.Hey Frank, I believe acetone is the same thing as "nail polish remover" and a heck of a lot cheaper. I get small cans of it from my local Woodcraft store, but I think most hardware stores will carry it.

Cheers,

Frank Corker
12-13-2007, 9:58 AM
Thanks Ed, I'll look for that next time I'm out, until then poor wifey!

Ed Lang
12-13-2007, 10:10 AM
Yes, nail polish remover is acetone.

Rose Hamacher
12-13-2007, 11:19 AM
I've gotta take time to thank all of you who suggested acetone for removing the marks - I am in the middle of engraving 150 4" paperweights, front and back - and have been scrubbing with novus 2 and then polishing with novus 1 - but I tried the acetone and it's a miracle! Thank you, thank you, thank you!

Regards,
Rose Hamacher

Larry Bratton
12-13-2007, 8:53 PM
I've gotta take time to thank all of you who suggested acetone for removing the marks - I am in the middle of engraving 150 4" paperweights, front and back - and have been scrubbing with novus 2 and then polishing with novus 1 - but I tried the acetone and it's a miracle! Thank you, thank you, thank you!

Regards,
Rose Hamacher
Rose:
Just a note. I read that some people have had crazing (stress cracks) occur on acrylic when using acetone as a solvent. Worse part is that sometimes it won't appear immediately. Acrylics are very sensitive to some chemicals.

Bill Cunningham
12-14-2007, 12:01 AM
Acetone is a solvent :eek: We used to cheap weld acrylic by soaking the edges in acetone for a few minutes, then clamping them together.. It would be my 'last' choice for 'cleaning' acrylic.. All the nail polish remover I have seen is laquer thinner which 'would' probably clean acrylic.. I generally use Acetone to bond plastic backed pins to name badges.. Works great..

Rose Hamacher
12-14-2007, 5:16 AM
Larry,

So you think if I wipe really fast and don't linger that the acetone will be okay? How about if I wipe with the acetone and then use the Novus 1 to clean any acetone residue off? My arm was just really getting tired of the Novus 2 - it worked, but not without some serious scrubbing. That's why I was so happy when I tried the fingernail polish remover! No effort. I knew it was too good to be true.:) Ha. But, my bottle does say it is 'fast and gentle' and has vitamin E and Aloe . . . I may have to risk using it. . .wiping really, really fast.

Regards,
Rose

Frank Corker
12-14-2007, 6:51 AM
Rose, I've been using my wife's nail polish remover for a long time on acrylic. I've never yet had any crazing or cracking.

Kim Uleberg
12-14-2007, 8:57 AM
Disregard my last post in this topic....hadn't read it properly :-)

We're having this problem too...about the residue, we usually wash it with industrial alcohol, thats what we wash all our signs with when we paint them. But we've never had this problem before...washing off the residue is fine, but afterwards it cracks alot! We tried with nail polish remover just before, and it cracked just as bad. This has never happend to us before, and we can't figure out why it happened now...the residue is easily fixed by using application foil on the area you engrave. But we paint the engraved area, and then to get the paint residue off we have to wash with something...we have always used alcohol, but now it has a tendency to crack...very strange, also that this has never been an issue before...

Mike Null
12-14-2007, 10:11 PM
Even though this thread deals with cast acrylic I'll relate my experience of today. I was engraving a pricey (for plastic) jewelry box today with a 7 letter name and a 50 point font.

I had engraved it a 600 dpi and a little slower speed than normal because I was looking to do a really neat job. When I took it out of the laser I realized it was extruded plastic. By the time I started to polish it with Novus 1 it began to craze and in a minute all the text was badly crazed.

Since the box was ruined I engraved the same name again using just an outline and again using 20% less power and a little more speed. Both of these were ok.

My thought is that the settings and depth (1/32") that I first used caused more stressing of the heat formed extruded acrylic material thus the crazing.

Anyway I'll be doing another one tomorrow.

Larry Bratton
12-14-2007, 10:41 PM
Rose:
Use at your own risk. Corker says his works, but who knows, that UK nailpolish might be more polite than ours.:D

Larry Bratton
12-14-2007, 10:59 PM
All:
I was recently posting a thread in EE about the use of Krylon Fusion paint on acrylic. I have been using that stuff on acrylics without any problem at all. Now understand, that paint contains some pretty nasty chemicals such a tolulene and the like. One of the members in EE said he tested on acrylic and it crazed it immediately. I went and painted more pieces just to test and I still saw no evidence of crazing from the paint. Go figure.

Is it possible that higher end acrylics such as those purchased from a commercial supplier opposed to the ones that come from Home Depot and the like are not as prone to crazing? I have also noticed that laser cut extruded is more prone to crazing than cast just by cutting. Is it possible that it could vary from lot to lot from the same manufacturer?

I notice that acrylic mfgs usually recommend soap and water to clean it. I don't use alcohol for cleaning for fear of crazing. I am leary of Windex and avoid the type with ammonia in it. I usually just wipe it with one of those microfiber cloths and water. It just seems that their seems to be no real pattern as to what is going to cause it to craze. Maybe I'm just CRAZY!

Darryl Hazen
12-14-2007, 11:18 PM
Krylon Fusion paint is formulated to mildly attack the surface of plastics so it will adhere to the plastic better.

Scott Shepherd
12-15-2007, 9:02 AM
Larry, I have personally had that happen to me with Black Fusion paint. I posted it somewhere on here, but to repeat, I cut out a rectangle with the laser, peeled off one side of the paper, painted it with Fusion, two coats. Engraved the signs, peeled off the front paper, and noticed all the edges were crazed quite heavily.

Went back to normal black Krylon, did the same job, same material, no crazing at all.

It's all Acrylite material. Extruded.

Larry Bratton
12-15-2007, 2:47 PM
Larry, I have personally had that happen to me with Black Fusion paint. I posted it somewhere on here, but to repeat, I cut out a rectangle with the laser, peeled off one side of the paper, painted it with Fusion, two coats. Engraved the signs, peeled off the front paper, and noticed all the edges were crazed quite heavily.

Went back to normal black Krylon, did the same job, same material, no crazing at all.

It's all Acrylite material. Extruded.
Scott-mysterious stuff. I painted this I tested the other day with red. I wonder if the chemical composition varies from color to color? I have also used some Rustoleum Metallic Gold which turned out beautifully. No crazing with it at all and the color is beautiful. Much better than Krylon's gold. Guess it's best to test. Problem is that sometimes it won't craze immediately.

Scott Shepherd
12-15-2007, 3:03 PM
Larry, according to the MSDS, here's the break down sorted by Parts Per Million :

Krylon (Normal- Black) :

Propane
Butane
Ethylbenzene
Xylene
Acetone
Methyl Ethyl Ketone
1-Methoxy-2-Propanol Acetate
Carbon Black

Krylon Fusion Black :

Propane
Butane
V.M.&P. Naphtha
Toluene
Ethylbenzene
Xylene
Acetone
1-Methoxy-2-Propanol Acetate
Bis (2-ethylhexyl) Phthalate
Calcium Carbonate
Carbon Black

My uneducated guess is it's the Naphtha that causes it. No reasoning to back that up because I couldn't tell you anything about any of the items listed :)

Larry Bratton
12-15-2007, 3:19 PM
Larry, according to the MSDS, here's the break down sorted by Parts Per Million :

Krylon (Normal- Black) :

Propane
Butane
Ethylbenzene
Xylene
Acetone
Methyl Ethyl Ketone
1-Methoxy-2-Propanol Acetate
Carbon Black

Krylon Fusion Black :

Propane
Butane
V.M.&P. Naphtha
Toluene
Ethylbenzene
Xylene
Acetone
1-Methoxy-2-Propanol Acetate
Bis (2-ethylhexyl) Phthalate
Calcium Carbonate
Carbon Black

My uneducated guess is it's the Naphtha that causes it. No reasoning to back that up because I couldn't tell you anything about any of the items listed :)
Somebody said it was the toluene. I looked up the info too and I believe the red was 15% tolulene but again, I had no ill effects from it. I also see Acetone in both of them. Naphtha is plain old lighter fluid isn't it?