Does anyone know what sort of additives - fillers,

Does anyone know what sort of additives - fillers, such as TiO2 - are combined with ABS plastic that is used as filament for 3D printing? Or is the ABS we use generally pure?

Thanks for your insights!

As far as fillers…no. Our filament doesn’t contain fillers (I suspect filament with fillers quickly gets found due to clogs, etc and filtered out). Plasticizers, colorants and stuff like that are added to some batches, I’m sure - but largely these formulas are kept behind closed doors, so there’s not much info for those batches of filament that do use additives.

@Vik_Olliver would probably be the go-to guy for answering this, as he runs filament maker and supplier

Coloured filament will generally use TiO2, but lots of ABS is a yellowish colour, so an “optical brightener” may be used to make it look whiter. Pigments need a white background to reflect off, and this is generally all concocted as a “master batch” with flowing agents etc. by specialists, which is then added to the granules to produce the desired colour. We do use fillers in some specialist plastics to stiffen them (Tactical Black for example), but not in our usual PLA, ABS and ASA.

A UV stable replacement for ABS for use outdoors in weather vanes, external equipment housings, turbine blades etc.

That’s great information. Thanks @Vik_Olliver !

I dissolved a bit of clear ABS in acetone, and the solution turned white. If you have any insights on whether that’s from the ABS, or from something in the ABS, that’s what spurred my question.

ABS contains an opaque synthetic rubber to make it impact resistant. This may be what you’re seeing.