Primer is insurance to give paint the best chance of adhering to the model, particularly on metal and shiny plastic parts.

First off, I applied Tamiya Metal Primer (TMP see Category: TIPS -TOOLS/TAMIYA METAL PRIMER) with a thin round brush to all the metal parts of the body except the couplers.  I put it on the plastic Kadee air hoses as well.  It dries quickly and very thinly.  I made two coats.

I also applied this, using the thicker brush supplied inside the cap, to all wheel faces and axles (avoiding the treads & journal tips) and to the trucks.  I have found that TMP is very good for making paint stick to flexible plastic as found in typical truck material.  I used to soda blast plastic trucks, but with TMP I find that it is not necessary.  I made two coats here also, but usually one is okay.  As it dries very thinly, I find that I can lay it on rather liberally.

Prior to this build, I would airbrush Tamiya Metal Primer over the entire model.  However, this time I will try their Liquid Fine Surface Primer (LFSP) instead (see Category: TIPS – TOOLS/ TAMIYA LIQUID FINE SURFACE PRIMER).  TMP is a clear gloss which makes it difficult to see how much is applied.  LFSP is light grey, but the Westerfield resin used on this kit is light grey as well, so the spraying contrast isn’t great either.  But it was a bit easier to see than the clear.


GREX Xb airbrush with .30mm tip, ~20 psi*, 1-2” away from model surfaces.

*a .30mm[.012”] tip is smaller than typical for most double-action airbrushes.  Most have a .50mm[.020”] tip which is much larger (2.8x greater in cross-sectional area) and therefore could use less air pressure.

LFSP was thinned with normal hardware store lacquer thinner (although Tamiya recommends their lacquer thinner).  The ratio is about 1:1 – too little thinner causes the sprayed primer to make “fuzzies” on the model surfaces.  I airbrushed the underbody, exterior side and end sills first, but I think I used too much thinner as these took longer to cover.  The finish also dried glossy.  The exterior sides, ends, and roof were sprayed with a more closely 1:1 thinning and the appearance is less glossy, more like a semi-satin.  Strange.

I made a light coat of LFSP so as to minimize the loss of model detail definition.  I’m not entirely sold on it yet, although the result was very good.  I’ll try it again on the next build.

Next post: Wheels & Trucks