I was running a job through the pass through and one cycle absolutely fried the material. I hadn’t changed the material type (thick natural leather). I thought it was burning right through so I let it go. It turns out that it didn’t cut through so my guess is that the laser set the wrong focus height. This was abou 12:40 am.
Any chance that the material came up from the bed? Sad, though.
Yeah, that looks like it warped up. Air gets underneath, it causes a heck of a lot more char.
I pin down anything in the passthrough…the weight of the material hanging out of the machine tends to cause bowing…and charring. 
Oh no! I’m sorry your print didn’t turn out beautifully. I extracted the logs to investigate the problem, and I found that when your Glowforge measured the height of your material before this particular print, it found a different height than what was entered in the app (for Thick Natural Leather). If the Glowforge isn’t focused to the correct height, that can definitely affect the results of your prints.
Could you please try the following so we can investigate further?
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Try your print again.
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After you click “Print”, watch the printer head move to your material during the “Scanning” phase.
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A red light should shine from the printer head onto your material at this time. This is the Glowforge measuring the height of your material.
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Please note whether you see the red light land on your material. Since your design covers your material entirely, I’m concerned that the red light may not be landing on the material, resulting in an incorrect measurement.
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If the red light lands entirely on your material, please let the Print proceed, and let me know the results.
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If the red light does not land on the material, please feel free to Cancel the print, and let me know the date and time this happened.
Thank you in advance!
It’s been a little while since I’ve seen any replies on this thread so I’m going to close it. If you still need help with this please either start a new thread or email support@glowforge.com.