(This conversation was recorded and then published as a transcript on March 18, 2021. It transcribes, to the best of my recollection, the words of the magical rat who teaches me how to paint.)
Tamiya paint can be “thinned” using a dropper of Windex. Use the old kind with ammonia. A dropper is 5 ml. Don’t over-think it. Just put the dropper in the Windex, squeeze the bulb and then release it. This will pull 5 ml of fluid up into the dropper. It’s easy. Don’t over-think it. I usually put that much in paint if it seems too thick. It’s not much. But you might need another dropper. What you have to do is get in the habit of stirring paint, not shaking it. Shaking introduces air into the paint. Stirring is essential for brushing. Air bubbles don’t matter with an airbrush, but with brushes they are deadly.
Stir for a long time. You need to add a dropper of thinner to a bottle of paint that seems “thick” and stir, stir, stir. For a full minute or more. This will, believe it or not, result in thinner paint. If it’s still too thick, add more and stir AGAIN for about a minute. The stirring is very important. I use cut-up bamboo skewers.
For Revell, Testors, Badger or Xtracrylix I thin with water. I have added a little Windex to each of them at times but I don’t think it really helped much. Tamiya seems to really improve with the Windex. I have not used the Vallejo thinning medium. It might be helpful with Vallejo Model Air. That paint seems to need Windex for brushing.
So how do you know when the paint is thin enough? The key is to understand that you want a nice, wet layer of paint on the surface being painted. It should be right on the edge of running. I get runs all the time. You have to hold it up to the light and look for runs and pull them out with the brush.
All paints will thicken up and dry out over time. Once a year, at least, I pull them out, stir and check them. I may a dropper or two of thinner and stir the Hell out of them.
But the ultimate answer to brushpainting often has nothing to do with the “thin-ness” of the paint in the jar/tin/horrible plastic bottle. It has to do with the how “wet” the paint is in the brush. You have to learn to keep the paint wet in the brush, especially when painting teeny-tiny things like fine canopy bracing. This means that the drying speed of the paint must be retarded. I often dampen the brush with an acrylic retard and then pick up some paint from a wet palette. A wet palette is a few drops of paint placed on a wet paper towel. The whole shebang must be kept wet and wild like those videos that you know about just as well as I do.
So get splashy.
The only way to learn is to jump in and
That ends the transcript of the magical rat. No other information is available at this time.