How to remove seam-lines

May 29, 2008 at 20:05 | Posted in How-to | 3 Comments
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A seam line is the visible line left after you combine two symmetrical halves to form a specific part of your kit, for example the forearms. If left alone, it will give your kit an ‘unfinished’ feel to it. Fortunately recent MG kits have been designed in such a way that seam lines are well hidden so you don’t need to bother with them. But for most HGUC kits, seams lines are very visible.

So, I know of only 2 ways to remove seam lines. If you know of other methods, please share.

1) Use basic putty (the grey type) to cover the lines. Wait for it to harden then sand away the excess putty. The putty (if dissolved properly with thinner) will fill in the gaps between the seam lines. But the down side to this method is that you have to paint that part afterwards, if not you’ll be left with an unsightly grey line of putty over your seam lines.

2) Using modeling cement to bind the two parts. The advantage of using this method is that there’s no need to paint. The disadvantage is that it’s permanent. You can’t unglue the bound parts, not unless you hack it with a saw. I’m gonna show only the 2nd method, because that’s what I always do for my kits:

I’ll be using a part from my MG Gelgoog as an example. So the seam line would be visible if I join the two parts here:

Before that, you’ll notice that one half of the parts has protruding parts (herein referred to as ‘male’ parts) and the other half has holes (herein referred to as ‘female’ parts) with which the male parts will fit in. What I usually do is I cut a bit off the male parts and widen the female parts with a small drill. The reason for that is to allow more space between the parts to be melted by the glue. I hope that makes sense. Here’s what I was referring to about the male parts:

So then you apply glue, also referred to as plastic cement (like this one by Tamiya) around the edges of both parts, like so:

Then you combine those two parts together and squeeze them tightly. You’ll notice the parts with the cement will ‘melt’ the plastic, thus fusing the two parts together. You’ll be left with excess melted plastic in place of the seam line:

Now comes the fun part. After the glue has sufficiently hardened, you should proceed to remove the excess melted plastic. A file is recommended. Then you need to use fine sandpaper to smoothen the surface and eventually you’ll end up with something like this:

A word of caution, though. Some brands of plastic cement might leave yellow stains, particularly on white parts. If that’s the case, then you will have to paint that particular part. It happened with my Heavyarms custom.

So, removing seam lines is one of the basic steps in modelling. But if you’re observant enough, you will notice that some parts don’t need seam line removal like hidden places (e.g bottom of foot) or parts that will be covered up eventually.


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  1. Very nice advice! I found it really helpful.

    I’ll gonna follow your blog from now on! ;)


  2. Thanks so much for sharing this. Now, I always use the second method.

  3. Wow, thanks! I thought I was going to have to by putty, good thing I already have some plastic cement.

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