I like to build a lot and paint costs seem like a significant part of the cost to build. When I was doing a lot of large scale RC planes I was always put off by the cost of finishing so I developed my own high performance enamel paints and sealers for military RC planes.
Well, I love Tamiya paints and how they perform and was previously a Model Master Enamel fan. One day I calculated the cost of a gallon of model paint as a comparison to many other paints on the open market. The cost of modelling paints is right around $90 per gallon but enamel paint on the open market can be had for $9 per quart ($36 per gallon).
So I wanted to formulate a paint that would perform in an airbrush as well as Tamiya or MM. Water based paints are tricky when they are being applied to polystyrene. However, when I test the adhesion of Tamiya and other acrylics they scratch off quite easily. However, in model building this seems to be not so critical because of course they are static models and abrasion is just not going to happen.
I still use some Tamiya paints but for colors I use more frequently like OD or flat black I make my own now.
I thought about just going into the business of making paint but I would rather just make it for myself and share the data with other modelers.
For the skeptics out there, yes I am using cheesy art acrylics but it works great and pigment is pigment. I used to paint as an artist with egg tempera with natural pigments so I have a lot of experience with pigments and binders (egg, linseed oil binders etc.). The additives seem to be what is important and the paint I chose was based on the fact that the brand I chose tends to be quite flat (great for military subjects of course). I think my equivalent paint costs for a 1/3 to 1/2 ounce jar is under $.20.
The formula (amounts vary depending on the color due to pigment load etc.):
1. Folkart acrylic paint (1.50 per 2 ounce bottle) (available online)
2. Floetrol paint additive (flow enhancer to prevent marks and encourage leveling without running). FLoetrol is available at Home Depot in the paint dept. and one bottle is a lifetime supply.
3. Windex (surfactant/thinner). Available at the grocery store.
4. distilled water (thinner). Alcohol may be a better thinner as well but I have not tried it.
I usually add about 6-9 ml of Floetrol to a 2 ounce paint volume along with enough water and Windex to make it thin enough to go through the airbrush. Less thinner can be used for hand brushing.
Anyway, for some builders this may not pass the "giggle" test but I am convinced it works. I can set two of my 1/35 scale tanks next to each other and one is finished in my paint and the other is Tamiya and I can't tell the difference.
The paint formula goes through my airbrush beautifully and dries rather quickly. In reality I can't tell the difference between it and Tamiya.
I can add some comparison pictures soon.