How to fix seams

Taking a look at your standard gunpla box, you will notice how nice the kit in the pictures look. It is after you put the kits together that you notice differences between the kit presented on the box and the kit you have just snapped together. One of those differences you notice is on the two part pieces, they all look like they’re one whole piece, the line down the middle of these parts are missing. Granted this could be photoshop at work done to remove those lines; but for most model builders, those lines were removed using simple techniques.

There are several ways to fix seams in model kits. What works best for one person, may not be what works best for another. This article will discuss a few methods for filling in seams. The first method is to use your standard model building glue. Also called styrene glue, or solvent glue. There are several brands, tenax, tamiya cement and extra thin cement, plastistruct plastic weld, testor’s liquid glue, etc. In this example, I’m using tamiya extra thin cement. The cement basically melts the plastic, so that when two joining piece are pressed together, the melted plastic welds together. The following video demonstrates this technique.

When possible, the glued piece is held together by clamps while the glue fully cures. I allow the parts to sit and cure over night before any attempt at sanding the part. You want the plastic to be solid for the sanding process or the work to glue the two pieces will be undone.

For parts that I’m gluing together to remove seams, I do not sand the nubs if they are anywhere near the seaming edges. In the past, I’ve sanded down nubs before seaming parts. The problem with this is that the sanding process ends up removing too much material around the seam edge, and when the two parts are glued together, there is a huge gap. I had effectively sanded the gap into existence. So to prevent this, the two parts are not sanded prior to gluing the parts. In the next video, two pieces were glued together to fix the seam, but due to poor cutting technique and/or sanding the part before gluing, the part is damaged. Here, the same technique as the video above is used. Styrene glue and a piece of styrene. The same can be done with the left over tree spruce.

The part is left to cure over night, then it is sanded down to remove the excess plastic.

Once sanded down, the part is now ready for some primer to check the fix.

My personal preference in fixing seams is the above. But there are other methods that employ the use of putty. There are several types of putty for model building. Epoxy putties are two part putties that react when mixed and harden in a specific amount of time. Tamiya also makes a light curing putty that comes in a tube. This type of putty cures under light and is a very fast method for fixing damages. It takes some practice getting used to the light curing putty, such as not allowing it to sit under direct light for too long. The putty tends to degenerate if left under direct light for too long. Then there are the styrene formulated putties that come in tubes. These work similar to the styrene glue, it melts the plastic and air dries to cure. Care must be taken when applying this type of putty, as too much will eat away at the plastic. Below is a video discussing common putty types and an application on a part.

And sanding the above part after it has been allowed to cure overnight.

Now that parts are seamed together and sanded down, they’re ready for some primer.