I have posted about Tamiya Metal Primer (see CATEGORY: TIPS-TOOLS) which, among other applications, I use as a general paint primer for resin kits. The chief disadvantage in TMP is that it is clear, so seeing where it is airbrushed is a bit difficult. Because it is clear, it does not easily show surface imperfections.
A well known product is Tamiya Fine Surface Primer, available in spray cans in grey, oxide, and white. It is a good product that I have used successfully on brass car sides before. They also offer this for airbrushing, in the familiar square glass bottle (#87075), which until now I have not tried.

Yesterday, I played around with the airbrush-able variety. I used a GREX XB with .30mm tip set around 20 psi. Here are my take-aways:
- Stir well
- While it looks like it is thin enough to be airbrushed straight from the bottle, and it is, fine “fuzzies” appear on the model.
- It is recommended that Tamiya Lacquer Thinner (#87077) is used for airbrushing, but I did not have any so I used regular lacquer thinner and did not have any issues.
- A mix of 1:1 surface primer and lacquer thinner avoids the “fuzzies”.
- This mixture goes on very thin, so many passes are needed.
- It lays down smooth with a slight gloss (the spray can version is more matt).
- Lacquer thinner clean up.

Apparently this can also be hand brushed; I made a half-hearted test on a piece of styrene. By brush, there isn’t even coverage, so I assume than one has to apply many thin coats. I airbrush whenever I can so this is not a concern.
The verdict? I’m not sure but I will definitely try this on my next resin freight car build as it looks promising.