View Full Version : Newbie question re laser cutting Mylar.

Ali Fifield
07-08-2016, 4:52 PM
Hi, I am looking for suitable plastic product for a decorative stencil for wall art, furniture, etc.I ended up researching that Mylar was the way to go. Was unable to locate a Mylar supplier in NZ so bought from China. However the plastic got this orange burn from the laser as per attached photo. The engraver thinks it may not be Mylar at all? Your thoughts and experience would be gladly accepted. Thanks Ali

Gary Hair
07-08-2016, 4:55 PM
Looks like either polycarbonate or vinyl. Do a burn test to rule out pvc - search for it if you don't know what that is.

Ali Fifield
07-08-2016, 7:11 PM
Thanks Gary Hair I will conduct a burn test!

Dennis Heskett
07-08-2016, 9:38 PM
We cut a lot of Mylar. You have to tape (masking) the bottom side or it will burn. Mylar is the brand name for polyester. Not sure where you would find it in your location. As the other comments, if you are sure it is polyester it is safe to cut. Good Luck

Ali Fifield
07-09-2016, 5:45 PM
Thank you Dennis, in your experience would Mylar/polyester burn as per the photo unmasked? And when you say masked do you mean joining strips of masking tape to totally cover the bottom of the sheet?

Kev Williams
07-09-2016, 7:27 PM
Lasering polycarb gives off an icky yellow ash...

Lasering PVC turns it brown, and the ash is a reddish-brown, just like in the pic (and yes, I do ;) )

Might just be another type of plastic but I'd definitely test that stuff to see if it may be PVC...

Dave Stevens-Vegas
07-10-2016, 10:40 PM
That doesn't look like any of the mylar I cut here as solder paste stencils. I use the Duralar brand. I get it locally, here it is at Amazon. https://www.amazon.com/Grafix-Dura-Lar-9-Inch-12-Inch-Sheets/dp/B002544NHA/ref=sr_1_3?ie=UTF8&qid=1468204090&sr=8-3&keywords=duralar+clear

I raster, 80w machine @ 3% power, 100% speed. I don't use a tape backing, it's rastered directly on the honeycomb. I can get some slight burn marks on the detailed edges but nothing like that even when I was experimenting with higher power and slower speeds. Mine burned black or bluish black with too high power and slow speed with none or almost no discoloration at the right settings. What char there was is easily removed with a hobby knife.

I've also used polyimide film (name brand Kapton) with good results. http://www.mcmaster.com/#2271K2 It's a bit stiffer even in thinner sheets and seems to hold an edge better. It's also significantly more expensive.