I’m working on a Project that Prominently Features a Red PETG Top Surface that after the Printing is done gets Sanded with Grits from 400-2000 +Heat Treatment.
There is a Big Issue tho, After the Sanding is done, I can Rather Prominently see the Walls and Infill of the Layers Below. At first I suspected that I just sanded too much and that the internals weren’t really filled in 100% as they should, but after some testing and Closer Inspection, it just seems the Red PETG is just Transparent enough that I can see the layer below…
So how do I stop this from Happening? Thus Far I played around with Fan Speeds, Nozzle Temps (±10°C), Layer Hight and Ironing all Solid Layers with Mixed Success, non Satisfactory enough however…


Infill is different from top layer shells. The infill is a different pattern from the top and bottom layers, and a different pattern from the walls.
Usually the top/bottom shells are set to 5 by default, and the walls are 2. If you bump the top and bottom layers to something like 10 or 15, they’ll be much thicker before it switches to the infill pattern.
Hm I see, ill give it a shot thanks!
So No matter what I try, It only does Infill before 1 Layer of Top Surface. No settings seem to trigger anything else. Even putting infill at 0% makes it just hollow instead of producing more Top Surface Layers…
It isn’t an “infill” setting. It’s “top/bottom” settings. I don’t what slicer you’re using, but every slicer should give you the option to set the number of top layers and bottom layers.
Yes, top layer is set to 5 layers yet it only does 1 Top Layer since thats the surface. Rest is handled as Infill.
I tried everything from 1-100 Top Layers, nothing changes. Insides still get printed as Regular Infill.
Can you please upload some screenshots of the model you’re printing in the slicer, and the related settings? That’s really odd behavior.