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View Full Version : Ever notice not all Acrylic / Plexiglas is created equal?



David Fairfield
06-19-2012, 8:40 AM
Some of the clear plexi I have engraves beautifully, with a nice frosted finish. But some engraves with less pleasing results. Under the magnifying glass, the finish appears lumpy with a rough build up of melted and then solidified particles. Same acrylic manufacturer/brand/thickness and color. No matter how I adjust the settings, the "inferior" plexi seems less inclined to vaporize, and more inclined to melt, and results disappoint.

Anyone else notice the same thing and/or have a solution or a reliable supplier of consistently "good stuff"?


Thanks :)
Dave

Mike Null
06-19-2012, 9:16 AM
Could you be comparing cell cast acrylic with extruded? Cell cast engraves sharply with a frosted finish. Extruded can engrave with a clear look and some melting.

Martin Boekers
06-19-2012, 9:35 AM
Plexi is a real generic term, there are many things people call plex that really aren't, such a Lexan and polycarbinates.
Check with the manufacturer/vendor to make suer that what you have really is cell cast acrylic and not a similar version.

David Fairfield
06-19-2012, 10:30 AM
I'm definitely not confusing Acrylic with Polycarbinate like Lexan. This is clear acrylic, all from the same supplier (Delvies in UT) same manufacturer (made in Mexico), same label, same color and thickness. Just two different batches of the same material, with some unknown variation that makes it engrave differently. Both batches cut beautifully.

Can anyone suggest where to find a reliable supply of "the good stuff" ?

Dave

PS Delvies says this stuff is "cell cast."

Mike Null
06-19-2012, 10:33 AM
There should be several local distributors within driving distance from you.

Mike Chance in Iowa
06-19-2012, 3:24 PM
Are you engraving bare acrylic/plexi or does it have some sort of film/tape over it that you are engraving thru?

David Fairfield
06-19-2012, 3:36 PM
Bare, but I tried engraving through the paper, and through tape, to see what would happen. No improvement, maks it a bit worse I think.

Larry Bratton
06-19-2012, 3:58 PM
David,
I have been cutting and engraving the cast acrylic that is imported from Indonesia. I get it from Calsak in Atlanta (and other locations). I was somewhat skeptical about when I first saw where it came from but it is a good product and believe me, Calsak's prices are right. I buy 4x8 sheets and they cut it down to 24x36 sheets for me at no charge. I have also used the acrylic from Mexico, Chemcast, and it is also good but I believe the Calsak material is just as good. They stock almost all cast and the price is lower than the extruded they carry. I guarantee you it is a lot cheaper than Delvies.

Mike Chance in Iowa
06-19-2012, 4:05 PM
I too have found engraving through tapes & papers to make the engraving look as you described above - lumpy.

+1 for what Larry has said. Calsak's prices are right, more reliable then Delvies, and great customer service.

Larry Bratton
06-19-2012, 4:26 PM
10-4 on the service too. I can normally order today and have the stuff at my place in two days. I am one day from Atlanta via UPS ground. Every now and then their cutting dept gets backed up but usually no more than a couple of days. I just cut some of their material this morning and it was just beautiful.

I too have found engraving through tapes & papers to make the engraving look as you described above - lumpy.

+1 for what Larry has said. Calsak's prices are right, more reliable then Delvies, and great customer service.

Joe Pelonio
06-19-2012, 8:31 PM
David,
I have been cutting and engraving the cast acrylic that is imported from Indonesia. I get it from Calsak in Atlanta (and other locations). I was somewhat skeptical about when I first saw where it came from but it is a good product and believe me, Calsak's prices are right. I buy 4x8 sheets and they cut it down to 24x36 sheets for me at no charge. I have also used the acrylic from Mexico, Chemcast, and it is also good but I believe the Calsak material is just as good. They stock almost all cast and the price is lower than the extruded they carry. I guarantee you it is a lot cheaper than Delvies.
I use Calsak too with a local branch, but had the opposite results with their black from Indonesia. It cuts fine but with a dull, matte edge rather than the usual gloss, and engraving is a bit muddy looking, not as sharp and crisp as the Mexican made Acrylite. The clear from Calsak has been fine.

Larry Bratton
06-19-2012, 11:04 PM
Joe,
I've noticed that the Calsak material seems to be getting better as time goes by. I cut a whole bunch of 1/4" dark brown a couple of months ago and I had some issues with it not cutting completely through. I cut some 1/4 black today and it cut like butter (well maybe not like butter, but good clean cuts all the way through, paper on one side at 6s, 100p, 5000f. I also cut some 1/8 and some 1/16" with great results on it too. So, as companies become successful with their produucts, they have more capital to spend on equipment and quality control. Hopefully this is the case with this. Cast material can vary sometimes and one can suffer from that characteristic.

I use Calsak too with a local branch, but had the opposite results with their black from Indonesia. It cuts fine but with a dull, matte edge rather than the usual gloss, and engraving is a bit muddy looking, not as sharp and crisp as the Mexican made Acrylite. The clear from Calsak has been fine.

Rodne Gold
06-20-2012, 2:22 AM
Basically you get A grade and B grade cast , A grade will use virgin materials and will be without inclusions , surface dimpling etc. B grade might have contaminants , might not have been in the pressure/heat ovens for as long and might not have the long polymer construction of A grade.
I import and only buy A grade , there is about a 10-15% difference in price between it and B grade - not worth it for our type applications where fine detail and aesthetics are paramount.
Coloured acrylics have various dyes or colouring agents added , so a colour from one Co might react slightly differently to colour from another.

Larry Bratton
06-20-2012, 10:14 AM
Thanks Rodney, that's good info. Didn't realize it was graded and I suspected that about colors.

Basically you get A grade and B grade cast , A grade will use virgin materials and will be without inclusions , surface dimpling etc. B grade might have contaminants , might not have been in the pressure/heat ovens for as long and might not have the long polymer construction of A grade.
I import and only buy A grade , there is about a 10-15% difference in price between it and B grade - not worth it for our type applications where fine detail and aesthetics are paramount.
Coloured acrylics have various dyes or colouring agents added , so a colour from one Co might react slightly differently to colour from another.

Vicki Rivrud
06-23-2012, 9:28 AM
HI all,
I'm about to take on a project using the ChemCast 3030 glass green/ green edged acrylic.

Do you have any advice on settings? I usually do acrylic high power with low speed. I'm going to have to engrave large open text, engrave a channel for led wiring, then cut 4 bolt holes and then the plate itself.

With regular cast acrylic I've been using laser friendly paper mask, wet it thoroughly and go at it , raised off the iron bed.

On the sample piece I received - it was id'd but the laser engraving was not as crisp as I thought it should have been.

Thanks for any advice or feedback,

Vicki

John Noell
06-23-2012, 6:07 PM
Living on a small island in the middle of the pacific we get little choice unless we decide to import in quantity beyond our needs. Our local supplier just switched to a Chinese brand and at first we thought there was a problem with the laser. Incomplete cuts, tons of melt residue and very wavy edges. Our first use of it was for an order of chocolate molds, where the edge finish is critical. (The client asked that we hand polish all the inside edges of 96 small squares in each mold sheet. We declined that part and suggested he could do it for himself.) Of course, the client was waiting at the connecting airport on the big island for the molds and we were pulling our hair out trying to find out why we couldn't cut this stuff. It was only when I decided to cut some old stock (albeit not the thickness the client wants) and it came out perfectly that I realized we now have a big stock of useless perspex. Arghh! (BTW - any suggestions for using up Chinese junk acrylic or is it time for a big bonfire?)

Larry Bratton
06-23-2012, 6:15 PM
Maybe pose that question to your supplier?

Living on a small island in the middle of the pacific we get little choice unless we decide to import in quantity beyond our needs. Our local supplier just switched to a Chinese brand and at first we thought there was a problem with the laser. Incomplete cuts, tons of melt residue and very wavy edges. Our first use of it was for an order of chocolate molds, where the edge finish is critical. (The client asked that we hand polish all the inside edges of 96 small squares in each mold sheet. We declined that part and suggested he could do it for himself.) Of course, the client was waiting at the connecting airport on the big island for the molds and we were pulling our hair out trying to find out why we couldn't cut this stuff. It was only when I decided to cut some old stock (albeit not the thickness the client wants) and it came out perfectly that I realized we now have a big stock of useless perspex. Arghh! (BTW - any suggestions for using up Chinese junk acrylic or is it time for a big bonfire?)

John Noell
06-25-2012, 3:38 PM
Well I should have said, "The overseas supplier to the biggest hardware company in Fiji, which supplies all the other hardware companies, switched to a cheaper Chinese line." The local supplier says they have no other sources and "It's looks pretty clear." As the only customer in Fiji trying to cut it with a laser they don't see any problems they need to deal with. Now I am looking for a source that can ship to Fiji.

Larry Bratton
06-25-2012, 5:32 PM
Well I should have said, "The overseas supplier to the biggest hardware company in Fiji, which supplies all the other hardware companies, switched to a cheaper Chinese line." The local supplier says they have no other sources and "It's looks pretty clear." As the only customer in Fiji trying to cut it with a laser they don't see any problems they need to deal with. Now I am looking for a source that can ship to Fiji.

John, don't know who the manufacturer is in Indonesia, but it is in your part of the world. If you can find them, they might be able to help you. The material we are using that comes from there is fine. Good luck.

Rodne Gold
06-26-2012, 2:08 AM
Burn a small piece of the acrylic you got , if its premium cast , you should have a crackly flame and never get molten or flaming balls that drip. If it burns with a silent flame and drips , its extruded. yours sounds a lot like it's extruded ?

John Noell
06-28-2012, 12:01 AM
Yep, extruded! Nasty dirty burn with drips. Great test! I tried a piece of the old stock we were using and it crackled,, with no drips. I have some other (thin) extruded that cuts okay but this stuff is really yucky. Thanks Rodney!!

Rodne Gold
06-28-2012, 2:27 AM
On one hand , I'm surprised they bought extruded as its more expensive in China than cast , however if a lot of their customers cosntruct stuff or need tight thickness tolerance , then extruded is the way to go.
Tell your suppliers to contact Tina at Beijing Longstar in China for their stuff , we use em , wonderful products , excellent service .
However their minimum order quantities are high - we have to order at least 2-3 tonnes of stuff ( 2-3000kg) , a 3 mm clear 1800 x 1200 sheet is around 9 kgs and 5mm is around 17
2-3 tonnes sounds a lot , but its not if you mix and match thicknesses and colours - we only import clear and black in 3 , 5 and 8mm - other fancy colours we source locally.

John Noell
06-28-2012, 4:24 PM
I'm afraid that Fiji is too small (less than one million total population, much of that in rural villages) to think about such large quantities. I'm sorry you are on the opposite side of the world from us or we would try to buy some from you!

David Fairfield
06-28-2012, 6:20 PM
That is a really useful test, never heard of it before. So thanks Rodney!

Sam Gardner
06-29-2012, 2:37 AM
John I also live on an island in a vast ocean with population of only 90 thousand. I started to buy from local shop but they only stocked black, white and clear. Now i import directly from a distributor in Singapore (brand is Cho Chen from Taiwan, very good quality) and i go through 800kg a year, various colours and thicknesses. Then again I'm the only shop laser cutting perspex and have cut thicknesses from 1.5 to 12mm with my 25W GCC but mainly using 3mm for number plates and awards.