Painting gloss black?

[trentkane]

Am trying to paint gloss black on mdf ive done a undercoat and sanded it smooth, when am painting the black it is starting to go milky? is this cos its to cold? or the mix am useing? (thinner) am spraying with a gun.
any help will do .
Thanks.

 

[Robbie uk]

If your spraying it, it could be " Blooming" this causes a whitish haze to the surface due to low temperature. Can it not be done with a brush ? How many coats of undercoat have you done ? One might not be enough on MDF.