How to blank off window apertures

I’m trying to model a HST barrier vehicle and, instead of buying the Hurst Models brass kit to convert a Lima carriage, is there a way of filling the windows and smoothing them over? Lee Martin, by e-mail

George says: Model fillers differ in terms of suitability, so choosing the right type for the job is important. For large apertures such as windows, any filler will require something to cling to and the inside of the window frame will not be enough. Therefore, it’s always advisable to fix a piece of plastic card to the inside of the bodyshell first. Be aware that the re-fitting of any moulded glazing units may be affected by this new piece of plastic, so they’ll need to be modified accordingly. Most modelling fillers tend to shrink slightly during the curing process, so don’t be tempted to try and spread the material flush with the surface on the first attempt. Instead, build it up proud of the model and leave for around 24 hours to set completely. Milliput Superfine two-part epoxy putty is one of the most reliable fillers available. It sets rock-hard (if mixed correctly) and can be worked to an ultra-smooth finish, using a little water to help manipulate the putty into position. A file and abrasive paper can be used to work the cured filler flush with the model’s surface. When rubbing down with wet-and-dry paper (or sanding pads) begin with a coarse grade and work up to a very fine grit (such as 10,000 grade) in order to polish the surface to match the surrounding smooth plastic. Use plenty of clean water as a lubricant for the abrasives and clean the model thoroughly before priming and painting. Don’t be disheartened if the primer coat shows up some minor imperfections – simply add a little more putty, perhaps using a fast-setting, light-duty formula as sold by Tamiya, Squadron and Revell. Allow the surface to harden once again before rubbing down and re-priming. It may take a couple of tries to get a perfect finish, but this hard work will be rewarded.

Blanking window apertures is a simple job, but it needs to be done carefully. A light coat of primer will reveal any imperfections in the filler after the surface has been abraded.

Leave it overnight, then mix the two-part filler and spread it into the aperture with wet fingers. Leave the putty standing proud of the surface and allow to cure for 24 hours. 2

1 Remove any glazing before cutting a plastic card blank just larger than the aperture. Fix with liquid poly cement or epoxy adhesive and clamp with a clothes peg.

3 Begin flattening the putty with a broad file, taking care not to inhale the fine dust. Switch to successive grades of abrasives to achieve a flush and smooth finish.

4 Any small imperfections that appear before or after priming can be remedied with a fast-setting filler, such as Squadron’s White Putty. When dry, rub down carefully.