Weld seams are an often neglected feature on AFV-models, especially on older injection moulded ones. If you check a real AFV you will be amazed to discover all those more or less crude and MANY weld seams. I want to describe some methods I am using to represent weld seams on AFV models.

Soldering the weld seams

I started with a "normal" soldering piston but had some troubles as even after sharpening the tip it was too thick and I could not regulate the temperature - but it was good enough to do a KV I at least.

I then invested about $90,- for a soldering station, designed for soldering computer parts. The station provides a regulation for the heat and 2 different sizes of soldering pistons and different soldering tips. I still had to sharpen the tips by fixing each into a motor drill and wrap sandpaper around it. But I got a point, sharp as a tip of a fresh sharpened pencil, soon.

After having this prerequisite you can start working. I use a temperature between 220 and 240°C, depending on the plastic, and start "welding" the relevant area by holding the soldering piston in an about 30-45 degrees angle and dotting the soldering point very gently to the plastic. No matter if there is already a weld seam on the kit or not, the plastic is formed from the heat, representing something very close to a weld seam.

Thick weld seams

If thicker weld seams are needed I first glue a piece of stretched sprue onto the desired area and after 24 hours I start "welding" it. My best experiences with sprues are Tamiya old yellow or new drab ones. I did not try the orange ones. The old dark green ones are not melting smoothly and when touched with a soldering iron they transform into small plastic balls...

While welding, small plastic particles may stick on the pointer creating "plastic hair" on the kit. Do not panic, a tip of liquid glue will let it shrink and disappear. But there are even weld seams which are so tiny, that the soldering tool is too clumsy. I then glue a very thin piece (not thicker than a hair) of stretched sprue to the relevant area and gently stroke liquid glue over it for 2-3 times. After 10-20 minutes I start sticking a dental tool (a rounded needle or sharpened toothpick will serve also) into the sprue and create the seam.

Once finalized some seams may look to rough. Spreading some liquid cement over them makes them "softer". If some seams got too deep, mix up some putty with liquid glue and spread it over the affected area. You can also sand the seams with sandpaper or steel wool to make them smoother.

Working with Resin, white metal and PE-parts

There is a problem on resin and white metal kits as a welding tool does not affect these materials. If seams are required the stretched sprue variant has to be employed. There is one thing to notify as the sprue has to be superglued onto resin/white metal but then the plastics melting process is different. It does not melt like on a plastic base and only 3/4 of the sprue will melt and the rest is mingled with the superglue and does not change.

Tool holders, tie downs, light guards - these are usually made from etched parts. I got crazy in sanding off any excess of superglue in the area where parts meet the surface of the kit.

Look at any US WWII vehicle and discover that these parts were also welded to the surface, without having any excess removed. I therefore do not remove the superglue excess any more, as far it comes in a nice round shape, as it represents the "real" welding quite good. I sometimes even add some superglue gel to force this impression - and another good point is that the etched parts are better secured.

The putty method

by George Schachinger

There is another method of making seams by adding putty instead of a stretched sprue. It only works with weld seams at the very edge of the vehicles surface as for instance those of the German light armoured cars.

I prefer the "Modell Masters red putty". One has to dilute this with Nitro at a rate of approximately 1:3. This mixture is filled in a syringe and pressed through a needle of 0,9mm diameter.

The surface of the modell should be masked with tape so that only half a mm is exposed. When the putty is going to get handsafe, I rapidly hit the seam with the back of my crafts knife to add the irregular pattern. After the moisture turns dry, the tapes can be removed. If the edges lift off a little bit, you can stick them to the surface with Acetone and a soft brush.