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Category: Hints and Tips to aid Modeling Projects
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Using Bondo Auto Body Filler

How I use Bondo Brand Auto Body Filler on my Models to Fix Holes and Gaps.

For many years, modelers in all scales and our scale model car, ship, and military modeler cousins, have turned to many products to fill holes and gaps.  First and foremost is Squadron Green Putty.  This long standing hobby product is a favorite of many kit builders.  But at $14.42 on Amazon for a 2.5oz tube, it's not exactly the cheapest product in your modeling toolkit!  For $9.99 on Amazon, you can add a 3.0oz tube of Bondo Glazing and Spot Putty.  This product work nearly exactly the same as Squadron green, and may be slightly thinner in consistency allowing better application.

I switched to Bondo about 8 years ago, after reading about in on an online forum.  The user stated that it might be the same ingredients, or nearly the same, and caused no damage to out fragile plastic models (read: it does not melt plastic).

I use a cheap metal "clay tool" i bought at Wal-Mart to apply the putty.  Squadron makes putty tools as well, and they'll work just as well.  Squeeze a small amount into a old soda cap (metal or plastic work fine).  Gently mix the product, as usually an excessive amount of the liquid will release.  I typically will not fully mix the amount I squeezed out.  I then scoop some of the putty up with the clay tool and apply it to the model where I'm trying to fill holes.

Allow the model to dry.  I usually wait 2-3 hours, but it seems workable in our small applications after about 30 minutes.  I then use a large flat mill file on flat surfaces or sanding sticks on rounded surfaces.  Smaller jewelers files work great in small confines of the model as well.  Wile not a requirement, I often sand the area as smooth as possible.  In a later article I'll revisit the use of putty for bulges.

After sanding, primer can be applied to visually check to make sure all holes were filled and sanded flush.  Bondo can be applied over primer, so you can re-work any areas missed.  This Details West ACF 2970 Cu.Ft. covered hopper is now ready for final details, and will be painted in a foobie Southdown scheme.  I say foobie because the 2970 is not quite the correct car for Southdown (SDWX) cars, but with the reduction from 4 to 3 roof hatches, it'll fit the part on my layout.

Prototype: http://rrpicturearchives.net/showPicture.aspx?id=2199943

© 2019, Josh Baakko, https://www.modelrailroadtips.com