What's this brown stuff?

I got some new PLA, FilaCube PLA2, made in the USA and pretty inexpensive on Amazon. I already printed a moon lithophane lamp with it which turned out pretty nice, but I wanted to print another one and line out the few issues it had. So I printed this temperature tower, it goes from 230C at the bottom up to 190C at the top. On only one end, there’s brown crud at every level, though it seems to be worse at the higher temps. I did not see any evidence of this on my moon print, and I’m not seeing it on the new moon print I have going now. Any idea what is going on there?
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Presuming you haven’t recently printed some brown, or at least darker filement, & given that it increases with temperature & seems to only be in the finer parts of the print, I’m going to suggest the temperature is too high for that filament. If it was me, I would try another tower, going from 180C to 200C, in 5C increments.

I like FilaCube PLA+ red, and typically print it at 220 or 225C. My red temp tower (185 - 230C) shows no sign of burnt filament. My guess is that filament – perhaps from too little retraction – is sticking to your hotend and “cooking”. Recommend you inspect and clean the hotend and nozzle.


I would check the hot end and change the nozzle. Usually the first culprit is the bowden tube slipping up. There must be a perfect connection between the bowden tube and the nozzle. I think I had this exact same problem. I’ve had nearly all of them so how could I have missed that one?