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Thick Paper - Getting Yellowish Scorch/Burn Marks

I’m cutting 220gsm white thick paper into detailed designs but getting slightly yellowed edges. I didn’t notice it straight away but a day later I can see a few yellow smears - like scorched areas.

I used the library setting for the paper. Should I change something in the settings to stop this happening? (is it to do with speed?). Any help appreciated - I’m new at this laser game.

Thank you :slight_smile:

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Are the marks concentrated around the most detailed areas of your design?

I have had inconsistent char/smoke marks in high detail designs because the laser spends a lot of time in the same area and there is a slight build up of residual heat in thin materials like paper (at least that’s my guess at what’s going on).

In some of my previous work I have isolated areas of my designs to run in a second pass so that the laser won’t stay in the one area for too long before moving on.

Otherwise I find that reducing the power to the minimum that will consistently cut through the paper is worth doing for each different type and color of paper or card that I cut as each has a slightly different “sweet spot”. 

Hope that helps

Hey Daniel, the whole thing is detailed so the marks are all over it really. I’m cutting at a speed of 700 and power of 100%. It’s only just cutting through, with some bits that need a little extra help to come off (scalpel). I increased the material thickness (to 0.5mm) in a bid to help it cut better.

I’ve now taped it to a piece of glass (2mm and so I’ve increased the support measurement to 12mm) as I read that could help but doesn’t seem to have made any difference.

Any thoughts on what I should try next would be great!


I would try two passes at lower intensity. This gives the medium you’re cutting time to cool down before a second pass finishes the job. This will also save you from manually cutting. It’s worth creating a small test design with the same detail as the full artwork to play around with to perfect your setting. You may find you can run the same setting twice and literally re-run the job OR run one setting and then a lower setting. Tip: you can actually run this all of this as one job if you duplicate your artwork into another layer in the exact same position and assign the settings respectively—the laser cutter will cut both layers just don’t forget the setup as it’s not visually obvious on the canvas.

To lower the intensity you can play around with either speeding up the cut or reducing the power. I like to think of laser cutting as a game where the longer the laser sits in a spot or the more powerful the intensity the greater the burn. Things like blowing air via air assist helps cool the medium and blow soot away which cause marks. [Someone from Darkly please chime in if I’m incorrect or extra details (always been interested in how these things actually work)]

I know all of this as I have cut a lot of double corrugated cardboard with lasers. Trying to cut through two layers, one usually thicker than the other can light up in tight spots if you try to cut it all in one go with one high intensity burn.

Good luck!

Thanks for your advice Domenico, I’ll have a play with it and do some testing. I like the idea of duplicating the artwork and running it as a cut afterwards.