"burnt" looking edges on clear cut acrylic

[Warren Beard]

Hi All

As I get used to my new laser cutter my first main issue is cutting clear acrylic, I'm getting a brownish tint to the edges, I'm using cast Perspex so good high quality material and neither Perspex or the laser guys can tell me why?

Has anybody had a similar problem cutting clear acrylic?

Cheers

Warren

[Paul Phillips]

Warren, you need to supply a bit more info so others will be able to offer some help, what kind of machine, wattage, what type of Acrylic, how thick etc. The only thing I've ever seen leave a brown tint is Polycarbonate, are you using air assist? By the way, welcome to the Creek.
Paul

[Joe Pelonio]

Yes, more info please. Did you try cutting with the paper still on? I have cut lots of 1/4" clear with the paper removed and had no discoloration, so I suspect your settings.

[Keith Upton]

My main substrate is 1/8 clear acrylic and I don't get brown edges when cutting it. I leave the paper mask on both sides as well.

[Doug Griffith]

Just as a quick bit of information, how does it engrave? White or clear?

[Scott Shepherd]

Sounds like polycarbonate, not acrylic, but Warren seems to know what he's got.

[Warren Beard]

Sorry guys, more info.

I've cut 5mm and 10mm thick and got the same result, I'm using genuine Perspex brand direct from Perspex themselves, yes it engraved white and have been assured it's the cast clear acrylic I have.

Strange thing is they sent me a small piece of 20mm thick and it cut nice and clear but not sure what it was that they sent me and they not sure either

I get the same result with the plastic protective sheets on or not.

I'm using a GCC LaserPro X500 II 100w

I've (hopefully) uploaded an image of of some 5mm clear I cut, you can see the edges are not clear.

[Scott Shepherd]

That looks like a different colored acrylic, not clear. Something with a tint to it.

[Jon Sollee]

Definitely not a 100% clear acrylic. You should not have any "burnt" edges when cutting this...

[Glen Monaghan]

Agree, looks like the edge isn't clear because the acrylic isn't clear, rather a faint yellowish color. Edges typically look like a darker version of the acrylic's color, and those edges don't really look burnt either, just a dark tint.

[David Somers]

So.....it could be an artifact of the fluorescent lighting directly above the box, but I don't think I have seen anything near that color tint before?

Is it possible the material was exposed to something that gave it that tint? UV light? A chemical in liquid or gas form? etc?

Or is a soft tint like that more common than I am aware of?

Just curious, like always!

[Scott Shepherd]

Or is a soft tint like that more common than I am aware of?

Just curious, like always!

It's quite common. They make all sorts of tints. They look clear when looking through them, but when cut, the color becomes much more visible on the edges.

[Doug Griffith]

How does it smell? Acrylic is custom formulated all the time and it could have a high impact or UV package added to it (not that either of those would necessarily make it change color when cut but it's a start). Maybe it was an over-run from the manufacturer and got mixed in with their standard supply. I've seen it happen.

[Scott Shepherd]

Score it with a razor blade and snap a piece if half. If the color remains in the edge, you have a tinted acrylic. If it's clear, then it's something else.

[Warren Beard]

Hi Guys

Sorry for slow response, waiting for the Perspex rep to come in and see me regarding this but as far as I can see (and ordered) it is clear Cast Perspex. As soon as I have more details I'll update the thread.

Cheers

Warren