Airfield Models - How To

Scale Painting Techniques

May 05, 2015



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Airfield Models (http://www.airfieldmodels.com/)Preparing the Wheels for Paint

New tires usually don't look right on a scale model.  I normally thread a bolt through the wheel, lock it with a nut, chuck the assembly into a drill and then sand the perimeter with fine sandpaper to remove molding seams in the tire and to make the tire look slightly worn.

I also "wet sanded" these tires using 0000 steel wool with soapy water.  All of this is easiest to accomplish with the tires still on the hubs and before painting.

When you are finished with the tires remove them from the hubs if possible.  I spent a few minutes trying to find a way to remove the tires from the hubs of the Williams Bros wheels.  I don't believe they can come off without damaging anything but I could be wrong.  In any case, I resigned myself to painting the hubs with the wheels in place which makes things a little more difficult.

Wheel hubs are almost always molded plastic.  More often than not there are molding and manufacturing imperfections that should be corrected before painting.

For example, injection molded parts are attached to sprue which is basically a tunnel the molten plastic flows through on its way to the mold.  Unfortunately the people who remove the parts from the sprues often twist the parts off which usually removes a chunk of plastic.  Use a good putty or make your own to fill imperfections.

I mixed some talc into 30 minute epoxy and used a wet finger to smooth it into the blemished area.  The next day I sanded the filler to match the rim.  In this case the repaired areas are gray.  I used wet or dry paper with which I had previously sanded aluminum.  I didn't worry about the stains because they are on the rims and will be painted with aluminum metalizer.

Other than sprue marks and flash there usually aren't too many defects on the wheels I've seen.  Flash is the thin plastic around the edge of a part.  It is plastic that flowed between the two mold halves.  This can be scraped off easily with a hobby knife.

After the plastic is as blemish-free as you can make it you must meticulously clean the wheels in preparation for paint.  Wash them throroughly in a good degreaser that won't harm plastic.  Tri-Sodium Phosphate is an excellent degreaser and safe for plastic.  Do not use dishwashing detergents.  These often contain chemicals that make water sheet off dishes.  This same chemical can make your paint fisheye.

Rinse the wheels thoroughly and then shake off the excess water.  Do not wipe water off with a cloth or paper towel.  Both of these items will leave lint on the plastic and create static electricity that attracts more dust.

Slip the wheels over a dowel hanging over a shelf until they are dry.  Be sure they are thoroughly dry before you attempt to paint.  Often water gets between the tire and the hub taking days to dry.  The last thing you want is water to seep out and run across your wet paint or worse seep out while you're spraying thus becoming trapped under the paint which creates blisters in the paint and pretty much ruins it.

Avoid touching the plastic with your bare hands after you clean it.  Skin oils can affect paint adhesion as well as cause fisheyes.  In this case I handled the wheels only by the tires.

A jig that allows the wheel to be spun. I made a painting jig in hopes that it would greatly simplify painting the rim.  The idea is to place the wheel over the axle, place the paint filled brush against the rim and then turn the wheel and come out with a perfect circle.

The wheels I painted have a brass bushing glued in the hub.  The brass tube at the base of the dowel prevents the wheel from contacting the wood and rubbing the paint from the hub.

 
 

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Scale Model Aircraft Painting Techniques
Masking the Wheels

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Copyright 2005 Paul K. Johnson