Engraving causing burn marks on only one side of the engraved area

Title pretty much sums it up, I’m trying to engrave(bi-directional), and I’m getting heavy burn marks on only one side. The actual engraving looks fantastic. I’m using air assist, but I’m not sure exactly how much air to use. Everyone says the PSI they use but it’s a open ended system and no one measures their SCFMs. For this piece, I set the focus a mm above the focal point and ran 300mm/s at 30%.

I’m using a 60w laser with a Ruida 6445g, if that helps at all

Have you cleaned it? That looks like soot, not burn.

What would you recommend cleaning it with? Also, any idea why there is soot only on the right side of the letters?

I use methylated spirits/denatured alcohol - it’s cheap and works great.

The soot is probably being deposited on one side because of airflow.

Although I’m not a big fan of it, I think that masking tape is sometimes the right solution.
When engraving with the right power setting / speed it is not always necessary with a lot of air, try to reduce the air flow to only a little bit to keep your lens clean.
The direction of your soot marks confuses me a bit, usually they point in the direction of the extraction and the machines I have seen have the extraction either on the back or on the left side.

It’s a little more work to remove the tape if the engraving has a lot of closed shapes, but I have chosen to use clear packing tape as a mask on all my engraving now. If I can’t do that, then I put a coat of the final finish on first and then clean off the soot with water (assuming a poly finish"



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