The bottom of my cuts get a real bad black char in the pattern of the bed

Any advice would be appreciated.


1/8’ birch - proofgrade settings

Three things, you can mask your wood, you can adjust your settings, and you can use alcohol and a brush to clean up.


It’s called “flashback” and it’s normal to lasering on a metal grid. Try applying masking to the back of the material to keep from burning it. (It’s why the Proofgrade materials are masked front and back.)

You can buy wide paper masking tape like this:

Rub it down well to activate the adhesive.


Flashback, as pointed out above and discussed here many times.

As this is not Proofgrade material, support won’t be able to help (and it’s not a technical support issue), but Proofgrade is masked which protects the lower surface from it.

You can also elevate the material above the bed, which is how I handle non-PG prints.

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Perfect, now I know to look up flashback. What is a good way to elevate the material?

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I just use rulers I created, or scrap material of a uniform height. I would not consider this a commonly used method (I’ve never seen anyone else use it) but it works great for me.

Before the camera calibration, getting good alignment for printing on smaller pieces of material took some effort, so I have a few rulers cut from proofgrade materials. Now they come in handy again. I keep a tub of scraps next to my machine which goes in the burn barrel every month or so, so I can pull out smaller pieces for this kind of thing as needed (like if a long, thin part might need additional support)…

Everyone had good ideas but no one mentioned trialing some different speeds and powers. You may find speeding things up or reducing power to the point where it just makes it through the piece will reduce or even eliminate any flashback.


Thanks everyone. I didn’t expect to get so much advice so quickly. Hopefully I can learn and be useful on this forum soon. I’ll take all the advice and let you all know how it goes.