The Model Master airbrush thinner is good but it is too expensive.
I would go to a hardware store and buy some good quality mineral spirits and use it as it is basically the same thing and much cheaper. A quart will run you less than $4 which is about what Model Master costs for a pint. [:0]
Try mixing it 2 parts paint to 1 part thinner to start and see how that works.
Mike
“Wisdom is the right use of knowledge. To know is not
to be wise. Many men know a great deal, and are all the greater fools
for it. There is no fool so great a fool as a knowing fool. But to know
how to use knowledge is to have wisdom. " Charles Spurgeon