Paints seem too thin

Hi Modeller 1/72,

Sorry you're having these problems with your paint. You're biggest problem is that you're moving from oil-based to acrylic paints. It takes a lot more work to get a smooth finish with an acrylic. I wouldn't even attempt to brush a large surface, like the deck of a ship, with acrylic paint. Some people can do it, but they're the exception. You're right about the acrylic paint doing all the things you say it's doing. Surface prep is much more important with acrylics. You should wash the surfaces of the model first. I wipe everything down with alcohol before painting. I've had times when even soap and water didn't remove the mold release agent the model manufacturer uses to get the plastic to release from the mold. Next, you almost certainly have to prime the surface first. The plastic is just too smooth for the acrylic paint. It doesn't have the natural "grab" that oil-based paints have. Once you have the "grab" problem solved, you're ready to paint with your acrylics. Next, use a brush made for use with acrylic paint. The bristles are different than the ones used for oil paints. A general rule of thumb--natural bristles for oil paints and synthetic bristles for acrylics. Also, use softer bristles for acrylics than oils. That will help prevent you from pulling all the paint off the surface as you pull your brush through the acrylic. Right now, I think you're used to the heavy hand needed to move oils around. Acylics need a softer touch. This probably matters most if you are determined to paint large areas by hand. Unless you are using Vallejo's line called "model-air," which is made for use in airbrushes, Vallejo's acrylic paint is thick enough out of the bottle to brush on. I really like their acrylics for hand-brushing, but everyone doesn't. And the Tamiya paints are fine out of the bottle, as well, but they will dry a lot faster. You are right that you can't pull your brush back through acylics without making things worse. You can help things some by adding an extender that keeps the paint "open" longer and lets you work the paint a little longer before it starts to set up, but it sets up fast, almost no matter what. It will also help it settle out, or level, and dry more smoothly. Mr. Color leveling thinner is pretty good for this. What you really want to do is get an airbrush for large surfaces. If you're putting 5-7 coats of paint on, you'll eventually be saving money using an airbrush. Hand brush smaller details. An airbrush will also help you with some of the newer painting techniques, like modulation. I hope this helps. You're not dealing with anything anyone else who moved from oils to acrylics hasn't experienced!

Barrett

There may be a couple of different reasons you're encountering problems with Vallejo - as you've noted, it may be a problem with thinning and the only real solution to ultra-thin paint is to let it sit until it starts to thicken. You may also want to try thinning with distilled water, rather than tap, which may contain traces of chemicals or metals (hard water) that are throwing things off. 

In my experiences, surface prep is key to good adhesion. Make sure to wash the parts thoroughly and use a good primer before painting. Also, a wet palette is a great tool for Vallejo. Essentially, there is a wet sponge in the palette to provide moisture and a piece of filter paper goes over the top. I dispense a dollop of paint and mix it around until it picks up enough moisture for easy application. Never too thick or too thin and it makes setting up different shades of the same base color very easy, which is particularly nice when painting figures. Plus, if I have left over paint at the end of a session, it keeps the paint "fresh" and manageable even after a week when the palette is sealed up.