Wonderfest 2002 & 2008 "How-To Demos"


Introduction to Assembling Models

(along some helpful hints for filling in seams)
/(Hardware Modeling Basics)
(Page One)



June 9, 2002

Background - (a prelude to gluing and seam filling)

Before diving in and talking about things that can be used to fill in your models' seams, I wanted to talk about some ways that you may be able to eliminate the need to fill them in altogether.


If the kit that you are building is an excellent fitting one, then the need to fill in seams may not exist, or may be down to a minimum. Many of the models currently being released are very good fitting ones. They include releases from many of the Japanese Model Companies like Tamiya, Hasegawa, Fujimi and Bandai.

(Bandai's H.G. W-Gundam Zero Custom)


In addition, Revell/Monogram has been releasing some pretty good fitting kits. Before AMT/Ertl was purchased by Racing Champions, their first batch of models from the Star Wars Episode One Movie, along with their vinyl Rancor figure had been some of the best fitting kits that they had ever released.

(Revell/Monogram's Special Edition Babylon 5 Starfury MK 1)


Polar Lights models tend to be average to poor in the fit category. Since they are still relatively new to the modeling scene, I would expect (and hope) that future releases from them will gradually get better.


In general, model kits released today fit much better than their counterparts that existed five or more years ago. If you have a kit that has excellent fitting characteristics, you may have already eliminated the need to fill seams in on it.


How can you determine if your kit is a good fitting one? Also, what can you do if your kit is a poor fitting one? (I'm glad you asked).



You can use a technique called "dry-fitting" to do both. "Dry-fitting" is as it sounds. You fit parts of your kit together before ever opening up your tube of glue or bottle of liquid cement.


Look at the instructions, remove two pieces from the sprue that are going to be attached together and see how well they fit.

(Leg assemblies to the W-Gundam Zero Custom)


With respect to the removal of the parts, you should either use a pair of sprue cutters or carefully use an X-acto knife. (I prefer the curved, #10 X-acto blades).

It’s very important that you remove all of the excess plastic that was attached to the sprue, but DON’T remove too much! Doing either may lead to a poorly fitting model.


Back to the dry-fitting step - I have some modeling buddies who go so far as to completely assemble their aircraft models with this dry-fitting method. The way they do this is by taping the parts together, (using Masking or Scotch tape). In addition, some of the blue putty (called Tac 'N Stik) can be used as well, to temporarily attach smaller parts on.

What you are shooting for here is a kit that has been temporarily assembled, so you can locate and analyze fitting problem areas, working on them before you begin gluing your model together.


Other than a model kit that's just a DOG to put together - (caused by poor engineering or poor molds or both) - often some initial work can be done to help the kit go together better.


Different types of fitting problems

In general, there are two different kinds of fitting problems. The first is the one where parts don’t fit because they don't fit flush with each other, (leaving a resulting gap).

The second type of fitting problem is when one or both parts have too much excessive plastic, which causes the parts not to align or fit flush with each other.


With the second case, by doing dry-fittings, followed by carefully and gradually removing the offending plastic areas, followed by repeating this process a much better fit can result. Sandpaper and/or a #10 X-acto knife can be used to remove the excess plastic.

Again, go slooooow here and be careful with that X-acto knife if you end up using one.


With the first scenario in which the parts don't completely come together, you can resolve this by gradually shimming or building up the areas that need it. You can use thin strips of styrene to do this. (Ok, at this point you’ll have to open up your glue or cement and start using it).

As with the second problem, you should also very gradually build up deficient areas, doing repeated dry-fittings to test your results.


Even if either of these techniques does not completely remove all gaps, they should nevertheless be helpful in removing many of the seams that would otherwise result.


Some Gluing Tricks & the Use of Liquid Cements

Ok, once you've done the preliminary dry-fitting steps along with working on your kit’s fitting problems, you can move onto the next step: Gluing your model together.


Although both tube glue and liquid cements exist for assembling models, I STRONGLY recommend that you use a liquid cement. The reason for this is that a liquid cement is much better for fusing your adjoining parts together, since it melts the plastic.

Actually, it may be even better to use several different types of liquid cements: a thin, quickly evaporating cement like Tenax-7R, along with a thicker, slowly evaporating one like Plastruct’s Plastic Weld.

Testors and Tamiya also sell liquid cements, along with Ambroid's Pro Weld. There are probably a number of other brands available. Your best bet is to purchase a couple and give them a try, using the one or ones that you like best.


The reason I suggest using both a thin and thick liquid cement is because of the following: With models, it is often good to apply the thicker type of liquid cement to the inside areas that you’re gluing together, (if possible). By gluing your model together from the inside, you can apply as much cement to the areas as needed, without having to worry about damaging the surrounding details.

I used this technique on a number of the Babylon 5 Starfuries that I built. I ended up removing some of the kit’s plastic found at the rear of the four engine pods, since I knew that I would be covering these areas with the engine thruster caps later on.

It may be impossible to glue a model’s parts together from the inside. In this case, you want to liberally apply the thick liquid cement to the connecting areas of both of your attaching parts, and then attach them together. The trick here is to apply enough liquid cement so that the resulting liquid plastic oozes out just enough to fill in the associated seam. However, you don’t want to apply soooo much cement that the oozing plastic-cement mars up or destroys the details that may be found on the surrounding areas.


After you’ve used your thick liquid cement, there may still remain small (or large) gaps in the connecting areas that remain. Here’s where your thin liquid cement comes into play. Apply it directly into the gap area (on the "outside”).


By carefully applying it DIRECTLY into the associate gap, followed by applying some pressure and waiting a bit, you may be able to eliminate much if not all of the existing seams.


The reason I like Tenax-7R for this purpose is both due to its thin, watery characteristic, along with the fact that it evaporates very, very quickly – (within a matter of seconds). Both of these characteristics help reduce the possibility of harming surrounding surface detail.


There are a number of tools that can be used to apply a thin liquid cement directly into a seam. Heboc (the makers of Tenax) sell a pipette-like device called “Touch-n-flow,” that can be used. In addition, a very fine paintbrush (0 or 00) or some fine-tipped Micro-Brushes can be used as well.

In some cases, a light application of the thin liquid cement directly onto your connecting parts may be all you need to assemble your kit.  With this, you attach the two parts being connected together and then carefully apply a small bit of the liquid cement to the adjoining areas, (using the “Touch-n-flow” or a fine paintbrush). Capillary action will draw the glue down across the connecting area, along with drawing it down below the surface, to fuse your two parts together. Repeat this process as needed, until you've applied cement to the entire area.



Although liquid cements tend to work very fast, you may still have to clamp your parts together, to give the glue a chance to work properly. There are a variety of things that can be used to accomplish this. They are metal clamps, plastic clamps, clothespins, rubber bands and masking tape.

The type of clamp used is partially dependent on the contour and shape of the parts that you are attaching together.


What’s next?

Ok, you’ve gone through the dry-fitting stage, (doing the necessary plastic clean-ups). Also, you’ve carefully applied your liquid cement(s) to your model’s parts, completely assembling it. Unfortunately YOU STILL HAVE SEAMS IN YOUR MODEL!!!! (What can you do now???)


It’s time to apply a filler to those gaps!

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Copyright © 2014 by Anthony I. Wootson Sr. No material may be reproduced without permission. Unauthorized duplication is prohibited.