On most especially older models, the weld lines are made as engraved lines in the surface. As real weld lines are in fact raised, the reason this is done is unknown (from a technical point of view, it would be easier to make them raised, and aircraft model builders has to deal with raised bolts, which should be engraved). This is therefore an area of the model that should be improved. Luckily, it is easy to achive a good result with little work. In this article, three different ways to make the welding seams will be explained: Putty, streched sprue and photo etched.
To those not experienced with Milliput, it is a two-part epoxy putty, that is mixed in even amounts and forms a very hard surface once dry. The amount needed is not large - about one to two mm. of each bar will be sufficient, unless it is a very large model. After the putty is mixed properly (refer to the leaflet in the box), roll it out into thin rolls (not thicker than 0.5 mm.), depending on the width of the weld line.
Lay the thin rolls into the engraved lines (do this in sections of no more than 5 cm. at a time, as it'll otherwise be difficult to control) on the model, and press then down with your finger so that they don't lift later on. Now, with the tip of the blade, stab the putty randomly to create a pattern filled with small holes and craters. Once you're done, press your finger gently on the putty (so that the weld lines are not too raised, as they may otherwise break). if the weld lines seems a little wide, cut off the edges and do the stabbing work again. Once satisfied with the result, move on to the next section. Once done, leave the putty to dry for a day or two before you paint it.
Streched sprue can be used much like putty. In stead of rolling out thin rolls of putty, just stretch some sprue to the desired thickness. In order to make the patter, spread some thin modelling glue over the plastic rod to disove the rod (be sure not to get in on the model itself!). Then, stab the pattern into the rod, and let it settle for a few days. Only work in sections of two to three at a time, or the glue will dry too quickly.
Aber has made some weld seam patterns for modelling. These can be cut to length, and glued on the model with superglue to create "instant weld seams". For the corners, Milliput should be used to give 'bended' welding seams, or it will look fake.
There are advantages and disadvantages with these methods. The putty measure is slow and a bit tricky, and is the medium-most expensive method. On the other hand, it is the best way to create life-like patterns, and is very easy to learn. If you don't like what you've done, you can just remove the putty if it's not cured yet. The plastic rod method is a bit faster, and a lot cheaper. On the other hand, it is more tricky, and there is a risk the result will be marred by spilled glue. Unlike the two other methods, you only have one shot. The photo etched method is by far the fastest, but also by far the most expensive. The patterns look very uniform, and not at all like those seen on real vehicles. For fast solutions, it will work, and you can take it off with a sharp blade even when the glue is dry.
I prefer the putty method. I think it gives the most freedom of "pattern", and you can try as many time you'll like without using you life savings.
All contents written by Christian Ankerstjerne unless stated otherwise