hello everybody i am starting my first pait job i am useing tamiya acrylics problem is they seem to dry very quick when i am brushing them on i just wondered can i use tamiya thinners with the paint to keep it open longer if so do you know what amount

John, I don't think adding more thinner will help much, though it will take longer to dry, it will also streak more as it will be so thin. You are encoutering a common issue with brush painting Tamiya acrylics - essentially, they are not great for brushing, but work well in airbrushes.

Try these two threads for a starter:
Tamiya Acrylic Paint retarder

Help with brush painting

Priming the plastic will help, you can use a cheap aerosol car primer, white, grey or black. When applying the Tamiya paint don't try to cover it all in one go, do it thin and quick without raking it up again by respreading too much, let it dry properly, then coat again and maybe again... Must admit I haven't seen Tamiya retarder and haven't tried the Liquitext retarder with Tamiya paints, though it certainly works with their own acrylics.

Unfortunately once acrylic paint starts to dry, it can't be redissolved by adding more thinner, so you can't really do the same as you might do with enamels, where you can continually respread the paint even while it is starting to dry. If you try to it will get worse rather than better, as I expect you have found.

Hope this is of some help - as I say, this is a common problem and I would recommend trawling or searching this Painting forum for other threads that relate.

thanks for your help i will have to go slow and as you say put on thin coats until it looks right

In fact Tamiya is a airbrush only paint, Brushing it will be very dificult and frustrating. Vallejo product are good brush acrylics. Hooo man! how many test have I done to try brushing tamiya colors... The best result I had was diluted 60%paint 40% X-20A and then adding 10% water. but it took lot of layer and was on small surface. Since it is not made to be brushed you really should think of buying new paint or a airbrush. A first AB is not that expensive. Try to find something like a used badger 175 on the net. I went a long way with this low budget airbrush.

Hope I could help a little.

Model on!
Phil.