Photo Etching on PG

Is it just me or does it seem like we lose a lot of detail when photo etching on ProofGrade to the protective masking tape. I don’t know how many ‘failed’ cuts i have because it looks awesome while engraving, then pull off the tape and notice that all the hair detail for example was just on the masking tape and didnt even hit wood.

The issue then is, when i remove the tape before hand, everything is charcoal.

It would be awesome if Glowforge could account for the tape thickness, and adjust so that pure white is bare wood, NOT masking tape. So that any other levels of gray are guarantied to etch the wood, and not just the tape.

Still trying to figure out this new HD Photo setting. Seems they add post processing as well through some sort of filter, so your end result will NOT be as you see it on screen. A bit frustrating. as hardwood is more expensive.


In theory you could do this by using the “min power” setting with a manual engrave. Also, don’t forget there is a finish on the PG stuff. I find if the laser power is just enough to burn through the finish on the PG maple, that those areas are lighter in color than everything else.


I always remove the mask for photos. By messing with the settings and with the photo you can often get it where it has very little “charcoal”. What is left can be cleaned up with alcohol and a soft brush.

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Didnt know about the min power setting, thanks, I will take a look.

Good point on the finish too… I will play with the min power setting, maybe thats all I need to fix my issue. However, makes me think: Do they adjust power in relation to min power? I mean, if a specific spot required 10 power, and i set the min power to 10, does that elevate the spot from 10 to now 20.

Basically i wonder if it SHIFTS the power when raising the min power.

Good question. Maybe @Rita or @dan will know.

I think Dan doesn’t know. He says so in the following thread:

From that same thread, I gather that it does a more or less linear mapping between grayscale and min power to set power. With the exception of true white which maps to 0 power.

And please, I’m glad we have the setting available and hope we keep it. (It was implied that there are some regrets about adding it to the UI which worries me that we might lose it.). Since PG uses it under the covers, it’s be a shame not to have access to it for manual settings.


I hope this is true.

I think @jamesdhatch 's experiment, while fairly minimal, was sufficient to distinguish between scaling and clipping. Looks like scaling to me.

Unfortunately, while it might be linear scaling (or close to it) of the power, the result is unlikely to be linear because of the way the material behaves may not be a linear response and the translation of current into power density for the particular DtoA circuit they are using may not entirely be either.

But for me, the essential interesting question was the one you posed of clipping or scaling of the output.

Can confirm, don’t know. :slight_smile:

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This seems to be correct.

I ran engrave jobs of the same gradient, at 3 different “Vary Power” minimum settings: 0%, 25% and 50%.
The gradient runs from 0% to 100% white, from left to right.
All three jobs ran the power at 100% (not full).

The Y scale is commanded laser power (it’s actually done by dithering a full power beam, but I averaged the dither rate to get a percentage):

You can see, that when it hits the 100%, it drops to zero power.