Painting white

Hello, I'm painting a Biel-Tan army and I'm struggling to get a solid white colour. I keep getting a grey, off white colour and I'm wasting paint trying to perfect it. Any help?

Hmm.... the best I can recommend is to prime the models white first, GW sell white spray paint and red goes better as a solid colour on white than it does on black

I don't want to paint red though, white is the main colour in the army.

Oh, try cleaning the models first. Might get rid of plastic dust, which'll turn it grey.

with a cloth, or in warm water

Cold water. Warm water might slightly melt the plastic.

Ok, thanks.

Indeed, but spraying them white will make them white, it's also a good foundation for brighter colours if you wanted to add some red for instance, but just layers of thin paint should work if you perceiver