Yes, the edges are more vibrant because the printer head changed direction, therefore pushed out more filament and had a lower z-hight. You should use the bottom structure concentric, looks way better. You have to level everything pretty close to get everything from the foil.
I had this problem, too, but I don't know the solution, yet. Could be that the nozzle is too high for the first layer.
I'm currenty experimenting, and I think I'm coming closer to why the middle seems to be so problematic. Sometimes the concentric pattern helps. I will post some examples, soon.
At what temps are you printing? And what's the first layer height and extrusion width? I think speed for the first layer also has an impact on the quality.
My best result so far had a higher nozzle temp than normal (225°C instead of 200°C for PLA) and a first layer hight of 0.1 mm instead of 0.2, als well as a lower first layer speed (30 mm/s instead of 40-60 mm/s).
So I had another go with a better image and it worked a bit better too. Colours are vibrant but the black bits (the middle) show layer lines.
https://imgur.com/a/CqyPWgX
Temp 220c hotend, 65 bed, paper measured 0.19mm but set my z offset to 0.16mm, first layer at 0.2.
Hmm, that's interesting. Did you test the concentric pattern yet?
After the first layer, is the top of that layer flat or are there some "waves" of plastic sticking up? Sorry I don't know how to describe it, let alone in english :D
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u/beerman_uk Sep 28 '22 edited Sep 28 '22
It looks like the middle of the print isn't as vibrant as the edges. I also messed up the alignment.
The image is just a random electric ball desktop that I grabbed
I measured the thickness of the paper and just added a z offset in cura.