white ABS discoloration under LED light

[Gambo]

I think you provided the answer to your own problem. Filament is white because it has mixed with it a white pigment normally titanium dioxide this very white but opaque so the filament looks white by reflected light but being opaque the pigment blocks transmitted light so the only light that gets through is coloured be the filaments polymer natural colour. If you want to make a light diffuser you will need to use a transparent filament.

[leelauer]

I think you provided the answer to your own problem. Filament is white because it has mixed with it a white pigment normally titanium dioxide this very white but opaque so the filament looks white by reflected light but being opaque the pigment blocks transmitted light so the only light that gets through is coloured be the filaments polymer natural colour. If you want to make a light diffuser you will need to use a transparent filament.

Yeah that makes total sense now that you mention it.