CO2 laser inconsistent burn on wood

Hi LB community! Just started last 2 months. Have you ever had inconsistent burns on wood engraving similar to what I’m getting here in this photo? Two things: First is that the horizontal laser path is too obvious because some wood region is burning darker than other regions. Second is that the laser burn at the girl’s hair above the forehead is white when it should’ve been as black as the hair at arms level. I use a 60W CO2 at 300mm/s and 50% max pow, Atkinson Image Mode.

One sheet will have a good black color on the girl’s hair, but another sheet that is same type of wood will have a white color on that same portion of the image. I’m now at a dead end in my troubleshooting.

I’m just wondering if there’s still something i can do to avoid this by a change in settings, or if there’s nothing i can do with this problem because this is caused by the nature of the wood. This is Gemelina wood btw. Thanks in advance!

I have not worked with gemelina wood but have read that it is fast-growing wood, just like birch wood. With birch wood / veneer, you have similar problems because the consistency and quality varies greatly. This also applies to a large extent to bamboo.
Instead of “screw on all buttons” I will make a test on some material which has a very uniform quality in its property. This is primarily to make sure the laser is in order. When you can be sure that your laser is “stable” and does not cause your problems, then you need to find a better material for your images.

There’s a little trick you could try, it works for me when I want darker tones on BB plywood.
Make a mixture of water and soda and use a spray bottle for a thin layer of this solution, let it dry all depending on how much the wood absorbs.

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Thanks for the tip Bernd! I was eyeing for a greater engrave depth using a higher % power setting to achieve a 3D effect. So I haven’t tried the baking soda mixture yet, thinking that this technique would only apply to lower % power setting and thus a lesser engrave depth. But yes it’s worth a try. I’ll give it a shot then let you know how it comes out.

I think it is difficult to make 3d effects on an image with many shades of gray. But of course, everything has to be tried. :+1:

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