Im airbrushing Tamiya Red gloss acrylic onto a black plastic surface but it wont cover well and needs some kind of an undercoat. Ive tried using Tamiya primer from the can and thinned through the airbrush but it comes out too grainy and when the red is applied its not smooth enough. I know I can sand the primer first but its difficult on complex shapes.
So what can I do to get it smoother? I was thinking of using a Tamiya grey gloss or flat acrylic as an under coat. Will this colour work and cover well?
One other thing. My silver paint. (Tamiya flay aluminium) seems to rub off too easily compared to other colours after it has dried for ages. Why is this?
Undercoat any red paint with white or silver. The best would be to spray silver, then white, then red. Use flat paints for undercoats.
Try spraying the Tamiya primer from the can—you are covering large areas, so you don’t need precision from an airbrush. Aerosol paints are precisely formulated, including the spray head and valve, to be applied from the can.
While some experienced and highly skilled modelers advocate decanting aerosol paints, the practice is very hazardous and I don’t recommend it.
If your metallic paint, or any other paint for that matter, has poor adhesion, there are two possible causes:
The surface wasn’t clean enough.
The paint was drying before it got to the target surface.
The solution to No. 1 is obvious. For No. 2, reduce air pressure, get closer, and/or use a slower evaporating solvent to reduce the paint to spraying viscosity.
The silver paint actually rubs off from the outside in. Tamiya flat aluminium. This colour seems to rub off more easily than others to me but I dont know why?
Unfortunately no. Primers tend to be somewhat rough in texture by design. To get a smooth surface you would have to wet sand.
The principles and procedures used by auto body techs to paint a car are similar to painting models. Prep the body, prime, sand, repair flaws, prime, sand then paint…you may have to sand the paint too then add a second application. Sand yet again and buff and polish. Devils in the details.
The amount of work you put into a paint job will reflect the quality of it in the end.
Modern reds and yellows generally have poor hide, the ability of a paint to hide the color underneath. Silver obviously has a high reflectance and very high hide, and will reflect light passing through the red or yellow back into the color layer above it. Whites also frequently have poor hide, but white pigments have high internal reflectance, which increases the apparent brightness of the overlying red or yellow.
Even with these undercoats, multiple finish coats (two or even three) will often be needed.
Gray will improve hide, but will result in a less brilliant final color.
As Jerry said, there are no shortcuts to a good finish.
Flat paints are never as smooth as glosses. If your desired finish requires it, wet sanding of the final undercoat with 1200 or higher grit may be necessary. For a candy-apple finish, you will need to polish the finish coats! [:O] (One of the reasons I don’t do cars!)
Whenever I’m doing red, yellow, orange and lighter shades of green and blue, I always undercoat with gloss white. It takes 3 or 4 coats of color to cover the white, but the white just makes the colors pop.
Fred, the reasons I specified flat white are that flat whites generally have better hide than gloss whites, and that some gloss paints have “gloss enhancers” (often silicone) that interfere with the bond of the overlying coat, especially if the gloss white is thoroughly cured. For example, this was true of many Tamiya acrylic gloss paints in the late 1980s and early 1990s.
Have you tried using Mr Surfacer 1000 as a primer? Or thinning your tamiya primer a little more with a model safe lacquer thinner such as Mr Color Thinner or Tamiya Lacquer Thinner. On another note, I thin Mr Surfacer 1000 with Mr Color thinner and spray that through my airbrush.