Why does this white print as solid white, and what makes the PETG tough?
Two things sit behind it. First, pigmentation: the white masterbatch is dosed at full loading and compounded into the pellets, so the pigment is distributed through the strand rather than only near the surface, and printed walls read as an even white instead of a washed-out grey. Second, the polymer: PETG is PET modified with glycol, which interrupts crystallisation and leaves an amorphous, more forgiving material. Impact energy is absorbed by deformation rather than a clean crack, and the layers knit during the melt, so the bond between layers is stronger than in PLA. It is also far more tolerant of moisture and common chemicals than PLA, but it is not the grade for parts in sustained high heat.
Full answers below
