Tamiya paint

 Thanks everyone I will give these ideas a try.

Not to disagree with the wealth of knowledge here; I tend to handbrush tamiya paint here and there, drybryshing for figures, etc. It is a great paint product. However, if its just general coverage that you're looking for and don't have the patience needed for this paint; I would really suggest you just switch to another paint brand, one better suited to brush painting.

Thanks for the info I will use what I have and then probably try something else.

OK. That's probably why he's having trouble with this. Solvent based compounds sometimes do have to be thinned, while some others shouldn't be. It depends on the formulation that each paint manufacturer uses for their product according to it's base. If this is a little thick, then thin it - but only a little. Too much can ruin it, as the base won't dry since it's all thinner, and no body to it. Too thick, and the paint won't flow.  When paint pulls the previous layers off - it's too soft, and needs to dry longer,  not be thinned. This will only compound the problem.  

Tamiya are solvent based acrylics. Isopropyl alcohol with acrylic retarder is a good substitute for the Tamiya thinner.

Are these solvent based, or waterbased acrylics you're talking about?  I know that this may be a stupid question, but I've never used them.

Bill and Phil have covered it with a very smooth coat, and good adhesion, too…

plumline

What is the reason for the thinner.

When painted straight out of the jar, Tamiya acrylics skin over very quickly, inducing the "roll up" phenomenon described above. Adding the thinner reduces this by extending the drying time marginally, allowing the paint to remain "workable"  a little longer.

Another point to note: When working with Tamiya Gloss acrylics, I'd recommend a drying/curing period of at least 4 days as compared to 24 hours when using flats.

My advice on this is "don't."  Airbrush Tamiya, brush paint with Vallejo.  You'll be much happier, and Vallejo is so much more user friendly for brush painting, and can be manipulated in many ways.

Chris

What is the reason for the thinner.

If this is solvent based acrylic, then wait for 24 - 48 hours before applying anymore paint. If you've already cleaned up the area, then repaint with one full coat. Wait until at least one,or two days have passed. I know that this is a pain in the a*$,but it might be neccessary to guage the drying time accurately to see what effect further coats will have on it. If this does it again, do not add any more thinner to your paint, or to the jar. Any more thinning will only ruin it. Try painting on scrap styrene, or sprue from the kit to see what happens upon successive coats. Then do this 24 hours later. If this does it again - wait for another day. Sometimes if the paint has settled it may not want to mix well, and you'll need to remix it,and start from scratch. Keep us posted on  your progress.

In addition to what's already been said, do not paint Tamiya acrylics straight out of the jar. Decant a small quantity, add about 30% (by volume - 1 part thinner to 3 parts paint) Tamiya thinner and stir well.

Paint as Bill described above, using short even strokes, to the "wet edge" of the previously applied area of paint. Do not paint over previously applied layers until after they have cured.

The paint is Acrylic

First off - is this waterbased, oil, or acrylic? Some types of paint need a primer,or a surface preparation to make the paint stick to the plastic. Do you know what type of plastic this is = polystyrene, regular styrene, polyethylene. or polypropylene? The last two are too soft for waterbased paints and will need a primer,or surfacing primer that self-etches to the plastic. Try spraying with an automotive primer. If you have an airbrush, try spraying it with that, If not, mix the paint really good. Sometimes the main compontent - the binder isn't mixed sufficiently to adhere to the surface of your project. Sometimes oil also does this for the same reasons.  You might need to remove the paint with mineral spirits. and start over with primer, then paint it over to see what results this will give. Until I know what type of paint medium you're using, I can't really understand how to help you successfully.  Another thing you can try - wait 24 hours before applying a second coat. Some paint makers suggest that you wait 48 hours at the very least to keep the paint from acting like a solvent, and removing the first coat under it. I hope that this will help you in your case.

Tamiya paints are rather tricky to brush paint. Attempting to put on a second coat before it is properly cured (as opposed to merely dry) causes the paints to "roll up". Many people give up and switch to other, more easily brushed, paints and I can't actually say I blame them.

However, I use Tamiya paints exclusively and both hand brush and air brush them with no trouble. The key is to not be impatient. Many people will tell you to dip the brush into their proprietary thinner before the paint, and that works. But I find that unwieldy.

The way I do it, is to use short, quick strokes and always add paint to the wet edge. Tamiya paints actually do a pretty good job of leveling out, and don't need to be "worked" to lay down properly. Once the area has been painted, leave it for at least 24 hours, before putting on a second coat.