I haven’t seen the Inventables stuff to compare, but the top layer of some two-tone acrylic I got from eBay is super thin and it didn’t take much for acrylic solvent to melt all the way through that top layer. If the black on your material is paper-thin, like the white on this stuff I got, be careful with acrylic solvent. Like, test on a piece of scrap first.
IIRC, the mark on the left was made by trying to wipe away a drop of solvent. (blemish size: ~1/4 x ~1/8")
Nice project and interesting analysis of the issues. Keep learning!
lots of good feedback in here; i’m likewise curious to know what another (low-powered) pass would do for clean up. acetone was the first thing that popped in my head (as mentioned), or some really careful detail sanding with a dremel or other rotary tool.
additionally, have you considered cutting your coasters but leaving everything in place to serve as a jig, then peeling away material only over the areas you plan to engrave / raster cut?
All great advice, thank you!
Aaahhh…great idea! Easy enough to re-align perfectly, as long as the piece is perfectly horizontal the first time…
Oh, and btw, the black on white cut perfectly w/o any paper protection. I wonder if the white on red will do the same…hhmmm…I can try testing the scrap left over…
Wow…ok, yes, it is super thin, will be careful, and test it first, too.
I have, but they will tend to move around a bit due to the kerf, and so will probably be difficult to place them back on perfectly…
Acetone is very good for dissolving the backs of plastic nail brushes, and the bristles fall out.
Go with wooden.
Those short bristled brushes for oil painting, would be good for detail work. They’ve probably got a name, but I’m not an artist !
UPDATE, CHECK THIS OUT!!
So, I contacted Inventables yesterday, and never did I expect such an awesome response / action. Just, wow, they blow me away, and I have to shares this with everyone. I was waiting to hear back from them before posting any part of their reply, so that’s why I didn’t say anything until now…
Me: Subject: Should I remove the plastic protective film on acrylic sheets before rastering with a laser?
MAY 08, 2017 | 01:12PM CDT
Original message
Hi,
I got this result from rastering with a glowforge pre-release unit; should I have removed the plastic protective film first; is that sheet to be kept on only when vectoring?
I.E. a lot of the white was melted, balled up & re-hardened, rather than vaporized…
Thank You,
MAY 08, 2017 | 02:55PM CDT
Mo replied:
Hello,
Thank you for reaching out to us about this issue, and sharing the photo. I spoke with my colleagues, and they said that it is best to remove the plastic coating.
If you need more information about the specific cut settings, I suggest using the settings listed on the product page for the best results: https://www.inventables.com/technologies/white-on-red-laserable-acrylic-sheet
Since we don’t make this information clearly available on the site, I am sending you a replacement sheet of the white on red acrylic. You should have it by tomorrow evening, so you can try the project again. I would advise using the recommended settings if possible.
I apologize for the way your project turned out, but I hope the replacement sheets and removing the plastic coating will help. If I can help with anything else, or if you have any other questions or concerns, please let me know and I’ll do my best to assist you. Thank you again for your patience and understanding!
Sincerely,
- Mo
MAY 08, 2017 | 03:00PM CDT
NOOO WAY!!! You guys are awesome, thank you!! I wasn’t even asking for a replacement, holy cow, thank you again!
Do you have any idea know if those settings are applicable for a Glowforge, as well? It’s a 40 watt co2 laser…
Btw, a few people have asked for your response when I get it, so that their projects will work well, too; can you please let me know which part(s) of your reply you are ok with / not ok with me posting publically?
Thanks so much again,
MAY 09, 2017 | 12:09PM CDT
Mo replied:
Hello,
Thanks for reaching back out to us. I am glad the replacement sheet was a nice surprise!
You can feel free to use any parts of my response for use with public posting. You can also let others know that they can reach out to us with specific questions.
As far as the GlowForge goes, it is too hard for me to say. We have not received our GlowForge yet, and I don’t know enough about the product itself and how it works to be able to answer your question. Perhaps you can share the information I’ve given you with them, and they can let you know more about the specific settings on the machine.
Please let me know if I can help with anything else. Thank you for your understanding!
Best,
- Mo
And holy cow, I just got an e-mail confirmation from UPS at 2pm EST (half an hour ago) that the package was delivered. Just like GF & Rita, lol…
How incredible is that? Serious props, and many, man thanks, Inventables! Outstanding customer service, just wow…
I replied & asked Mo if they are on the Forum; fellow GF Customer, I guess?
They’re so good like that. I had a positive experience with them aswell when I ordered something that wasnt labeled as out of stock. They gave me a replacement even though it was a few dollars more expensive
oh man, what a really fantastic response. good on them; i’ll try to support them such as i can from canada, haha.
i’d try it on something simple, as that seems relatively overcome-able. there’ve been a few posts from beta and/or PRU users who have successfully flipped and engraved items, so i can’t see this being much worse.
That was me 
I think I was the first customer with a 2 sided cut, ever…
Still waiting to hear if @dan will grant me a badge for that, as @smcgathyfay suggested…wink wink, hint hint…
Yeah, been dealing with Inventables since late 2015. They have some of the best customer support. If a part breaks on my CNC they bend over backwards to help. When I order material it goes out the next business day and is usually at my house, 1000 miles away, 2 days after the order. I ordered a bunch of stuff recently with about 2/3 of it on back order. They shipped what they had, the next day shipped another third and the next day the rest of my order. My shipping cost did not change. Inventables ate the extra shipping. Most companies would have waited the 2 days and then shipped everything.
ha! got me, eh. annnnnnd i’m guessing it’s probably not worth setting up a proper jig unless you were doing a bunch of repeats.
Shop vac…a necessity in the shop…lol
Ran it last night without the plastic protective sheet…
What a difference; check…out…these…beauties!!
Original with plastic vs new without plastic
Btw, I tried cleaning up the original ones with a second pass, and I failed to align it perfectly, darn. But, check out how nice & deep the 2nd engrave is, and therefore how much stronger the color is!
Keep in mind though that this was done after a clean up; I am not sure if this would work well with 2 passes & no cleanup, cause if you do that, then you are running a 2nd pass over this (this is before clean up):
Oh, and a couple of notes: I ran this by choosing the automatic settings for ProofGrade 1/8th White Acrylic, and then cleaning them up with lighter fluid & rubbing with a paper towel, as well as then washing with dishwashing soap and water. I also used the fluid on the edges, as they were a little tacky, as inventables warns can happen with too high a dpi setting, and they were then perfect.
I tried using the settings recommended by inventables on the left over scrap from the first run, but I had to shrink it down to 1/4 inch x 1/4 inch to fit, and the settings were too strong; the engrave cut through, and the cut melted / warped the material. I should have taken a pic, sorry, will post that tonight. The GF automatic setting worked perfectly on that small size, too, though…
Awesome, much better. I was hoping it was just the plastic cover.
Can you explain why lighter fluid?
Before this thread this is the first I’ve heard of using it to do cleanup work.
I originally used it for removing the sticky glue residue left over from the proof grade protective paper and / or masking tape on other acrylic prints. (I also found that it also cleaned up scorch marks pretty well, but that’s a side note).
Then I found that even though I hadn’t used any adhesives tape on the first coaster print (the black and white ones), the residue that was left behind was kind of tacky / sticky, and resembled the glue left behind from the tape / pg paper. Well, that adhesive is usually petroleum based, which Is why lighter fluid (and other petroleum distillates dissolve it and clean it up so well), and I figured since acrylic is a (maybe??) a type of plastic, and I think that the 1st color of the 2 tone is (maybe?) a type of plastic, why not try the lighter fluid on this, too…and voila! Worked really well, especially on the red / white ones.
And now I know!
I assume this would be something similar to people using products like Goo Gone to get rid of residue?
Yep; Goo Gone, WD-40, 3-In-One, Gun Cleaning Oil, old formula roach sprays, (I THINK) Johnson & Johnson Baby Oil: all petroleum distillates…
Side note: Edible Oils like Olive Oil work pretty well, too…not as well, though, and can stain fabric, but at least they are non toxic.
Also known as naphtha or white gas. Used in lighters of course or for starting your charcoal grill or in white gas camping stoves.
BTW, also used as the fuel for fire eaters in circuses, carnies and renaissance fairs 
