How-To: Coil Spring Clean Up

The cleaning up and removal of mold seam marks and flash is a routine task for scale modelers striving to make their project look more like the real deal than just a toy copy. The smaller the part, the rounder the shape of the part and the more complex the parts shape is the harder it is to remove the unwanted marks from them. Take those coil springs found on car, aircraft, armor and ship models. Whether they are a part of landing gear, suspension or recoil mechanisms, they present a difficult challenge to clean up.

A novice modelers might give the outer edges a swipe with a sanding or polishing stick or paper to clean it up, but the advanced builder wants to clean up between the loops in the coil as well as the inside edges of the spring itself. You could try using a piece of folded sandpaper, tiny jewelers files or very small dental burs…but there is yet another and easier way to get at this unwanted seam and corresponding flash. STRING!

I’ve mentioned here before on a couple of occasions how to use string or thread to cut opening cleanly and precisely. Well, you can also use it for working those areas between such things as the space between coils of springs.

Use a piece of string, floss or thread suitable in size for the gap between the coils. Wrap the string around one turn of the coil and with tension pull the string back and forth to sand away the mold line. Be careful not to break the part or get too carried away and cut the part in half! Again, the bench vice from Excel holds the part firmly yet delicate enough not to break it.

You can work the string to clean up the outer circumference of the spring using the string or the other methods you are currently using.

This method will help you give the coil spring a more three dimensional appearance, and we all know some of those molded on springs lack detail. So if you’re not ready to make them using wire, and want to build out of the box, here is a technique to help you do just that.


  1. Hi Gerald – this is a good one… I never think about string in these tight situations.


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