FILLING IN

When building brass or whitemetal kits, I’m happy filling in any gaps between parts with solder. When cool, the solder can be filed flush with the surface, leaving a seamless bond. If it’s a big gap, more than a millimetre say, then I cut a length of flat brass to bridge the gap, flood it with flux, lay a length of four-core solder on top, add more flux and then gently heat the surface with a blow torch flame. This has a ‘fluid effect’, allowing the whole joint to melt and gel together giving a smooth and resilient joint.

All this is fine for metal, but boy, have I struggled over the years trying to find a suitable filler for use with plastic kits and parts. Now that I’m using more and more 3D-printed components, the need for a reliable plastic-compatible filler has become more urgent. I know you can’t solder them, which is my first love, but now I’ve finally found the solution, in the form of P38 two-part filler. Yes, it is a big tin, and it does whiff a bit, so always be sure to use it on top of a mountain or, at the very least, a well-ventilated room!

Using a small spatula, fetch a small amount of the grey compound out of the tin and you can use the lid as a mixing palette. Add a small amount of the red Hardener and mix thoroughly to a pink solution, free of any colour streaking, then apply the putty to the gaps or holes needing to be filled. My Class 69 conversion project (see page 46) required quite a lot of filler, making good various unwanted holes and recesses, along with blending in new components.

The P38 filler goes off quite quickly, so don’t hang around with the application and don’t worry about getting things perfect yet. After an hour or so, you’ll be able to file and sand the surface back to a super-smooth finish.

No shrinking, no dips, this stuff just works well. Shrinking is one of the most irritating problems I’ve encountered with other fillers and putties over the years. The big tin will last for (almost) a lifetime, provided you keep the lid of the tin clean and the lid on tightly. And don’t be worried about using up the small sachet of hardener, as you can get spare pouches easily enough on Ebay or other internet sites.

Solvent based fillers must be used with care. Work in a well‑ventilated area and wear a facemask when filing and sanding the cured filler.

A tin of P38 two-part car body filler provides an excellent medium for filling holes in various materials, especially plastic, resin and 3D-printed parts. It’s readily available from automotive stores, such as Halfords. Aerosol-based filler primers are also recommended, particularly for 3D-printed components, as the thicker paint helps to smooth out the ripples on the surfaces. The primer needs to be built up over several thin coats though.