Category Archives: Model Building

Glue for plastic models and buildings

I saw a question for the millionth time on a forum about what glues to use on plastic models and buildings. So I’ll cover the topic here, where it won’t get purged after 8 months.

Ask the question at a hobby shop, and the answer comes down roughly 50/50 whether to use some type of super glue (cyanoacrylate, often abbreviated CyA or CA), or some type of MEK-based plastic weld, such as Tenax 7R. Every once in a while, someone pipes up about the tube cement I used as a kid. You don’t want to use that stuff. If you’ve ever tried, you know why–it’s messy, dries slowly, and the bond isn’t as strong as it could be. Read on and I’ll give you the advantages and disadvantages of both alternatives, plus some secrets.

Continue reading Glue for plastic models and buildings

Can you use 1:64 vehicles with HO scale trains?

Can you use 1:64 vehicles with HO scale trains? It’s a common question. The answer is you can do whatever you want.

The next question is whether you’ll be happy with it. And under some circumstances, you might be.
Continue reading Can you use 1:64 vehicles with HO scale trains?

Don’t paint on Mondays (or any other bad day)

I should have stayed away from the model kit.

I was looking for a way to unwind after a long day. I don’t know why it was long or hard. It’s not like I got jinxed by hearing "I Don’t Like Mondays" by the Boomtown Rats on the radio today or anything.

But I don’t need to tell any more of the story than this: I got in a hurry, and I got burned.The correct way to paint with a spray can is to spray a light, almost translucent coat onto your work, from a distance of about a foot. It helps to aim a little bit away from your work even.

Krylon commercials say no runs, drips or errors, but guess what? Shoot too much from too close, and the paint will run like Carl Lewis every single time.

So what next?

I’m going to go find a zipper bag, pour some Purple Power or Castrol Super Clean into it, drop the piece in there, let it sit overnight, pull it out, rinse it off, and be presented with clean plastic. Then I can start over.

So there’s good news. At least starting over is an option.

In the meantime, I need to keep telling myself that you can enjoy a well-built model for decades, so it’s worth putting a few extra hours into it.

Easier said than done.

How to assemble a plastic model kit

Several months ago I bought a plastic model kit for the first time in probably 20 years. This past week I started to put it together.

I’m doing things differently this time.

Wash the parts

Plastic models have mold release on them, which makes it harder for paint and glue to adhere to the parts, making for a weaker model. The first step to building a proud model is washing the parts with dish detergent. Then avoid handling them with your bare hands as much as possible afterward.

Use better glue

The guys at the local hobby shop argue about the best glue to use, but they agree that the Testors stuff that comes in the tube isn’t it. It’s better to use either a plastic welder like Tenax-7R, or one of the many super glues on the market. Tenax welds the plastic together and actually makes one piece from it. The downside is its nasty fumes (wear a ventilator to save your lungs and your liver–really) and its permanence. Super glues work about as fast but make a chemical bond. The upside to super glue is that if you make a mistake, you can put the mistake in the freezer overnight, and then you’ll be able to pry it back apart and glue it again.

The downside to super glue is that it happily glues skin, so get a debonder from your hobby shop to bail you out if you glue your hand to your model or if you glue a couple of body parts together accidentally–putting your hand in the freezer overnight doesn’t work very well.

Both glues result in a stronger bond than the old tube glues we used to use.

Trim the flash

There’s always extra crud on the edges of your plastic pieces, due to the molding process. Trim that away with a hobby knife. Usually just slowly running the blade across the edge is all it takes.


When you glue your pieces together, there are always gaps in them. You can get plastic putties that chemically bond with the plastic and those are the best to use, but even a household putty like Durham’s Water Putty is better than gaps. Ideally you want the putty to be a different color than the plastic so you can see your work better.

Use primer

You should always paint your model, even the parts that are molded in the correct color, for reasons I’ll get to. But before you paint, you should prime the model. Use a good-quality primer like Krylon or Rustoleum Painter’s Touch. They are less expensive than hobby primers and they work extremely well.

Primer does several things. Paint sticks much better to primer than to plastic itself, so if you use primer, you can use thinner coats of paint, and you can also use paints like acrylics that normally won’t stick well to plastic. Second, primer can fill in minor flaws in the plastic, and make flaws that need to be puttied more visible. Third, primer makes the detail much more visible, which helps you paint better.

Spray on a very thin coat. It doesn’t have to cover completely.


Models should be painted for two reasons. The real thing is painted, so your model will look more realistic if it’s painted. Bare plastic looks more like a cheap toy. Second, decals don’t adhere well at all to bare plastic, because they are designed to adhere to paint.

The best paints to use is also a matter of religious debate. I like to use acrylics for the parts I have to brush paint, because acrylics have no fumes and clean up with water. They’re cheap and easy to work with. I can get craft acrylic paints for 60 cents a bottle if I shop around, and the bottles are big enough that they last forever. They’re cheaper than Testors enamels normally sold for models, and I don’t think they dry out in the bottle as quickly.

For the ultimate acrylic, visit a hobby shop that caters to wargamers and pick up some Vallejo paints. They’re thinner than the craft acrylics, so they’re less likely to obscure detail when detail counts. They also tend to be self-leveling, helping to conceal your brush strokes.

I prefer to spray rather than brush whenever I can, because then I don’t cover up as much detail, and I don’t get brush strokes. I can spray a light coat followed by a second light coat and get nice, even coverage. You can get sprays intended for plastic models at a hobby shop, but if you can find a suitable color from Krylon or another hardware store brand, you can use it.

An airbrush is nice, if you can afford its cost and can afford to invest the time required to learn how to use it and keep it clean.

So, should you paint before or after assembling the model? I find it easier to paint what I can before, and scrape the paint off the surfaces that need to be glued.

What if you really mess up the paint? There are ways to safely remove paint from plastic so you can start over.


When you need to paint an assembled model and you need to keep the paint away from parts of it, use masking tape. Don’t use the cheap beige stuff. Get some good blue or yellow painter’s tape, which is less likely to lift the paint that’s under it.

To keep paint from bleeding under the tape, you can either brush along the edge of the tape with the color that the tape is covering, or brush with some clear acrylic medium (look for it in the artist’s paint section of stores like Michael’s and Hobby Lobby) or, believe it or not, Future Floor Polish. This seals the edge, and if any of it bleeds under, it won’t be visible.


Dad and I could never get decals to stick right. What we didn’t know was that decals are nothing more than a clear lacquer sprayed on paper with something printed on it. They are supposed to bond permanently with paint underneath them.

So the first secret of applying decals is just to paint the surface beneath them. Decals stick better to glossy paint than flat, so if you don’t paint with glossy paint, apply a bit of acrylic gloss medium or Future Floor Polish (which is actually a clear gloss acrylic, not a wax), let that dry, and then apply the decal to that.

I have some additional waterslide decal tips and tricks if you’re interested in them.


When you’re done, spray a clearcoat over the whole paint job. This gives a consistent and more realistic finish. A gloss coat is fine if you want your model to look factory new. But for a more typical real-world look, use a clearcoat with a dull finish. Testors Dullcote is the standard.

Before you experiment with Krylon or another hardware store clearcoat, take some scrap plastic, paint it with the same paints you used to paint the model, and then spray the clearcoat over it. Not all clearcoats are compatible with all paints. I once tried Dutch Boy clearcoat on a plastic model and it caused the paint to bubble, ruining it.

Following these tips won’t make award-winning models, but it will make your models look a lot nicer.

A model railroad scale conversion chart

Plans in model railroad books and magazines are often in a different scale from your favorite. Having a model railroad scale conversion chart helps.

I’m into O scale and the rest of the world, it usually seems, is not. Dimensions for published plans are almost always sized to HO scale, or even S scale of all things. Of course, after A. C. Gilbert imploded in 1967 and took American Flyer with it, it seemed like the “S” is S scale stood for “scratchbuild,” because building it yourself was the only way you were going to get anything, so I guess that’s fair.

Here’s a cheatsheet you can use to convert measurements from one scale to another.

Assumptions: O scale is 1:48, G scale is 1:22.5. If you use a different measurement for either scale, I’m sorry. This won’t be much use to you.

G Scale O Scale S Scale OO Scale HO Scale TT Scale N Scale Z Scale
G Scale 213% 284% 339% 386% 533% 711% 977%
O Scale 47% 133% 158% 181% 250% 333% 458%
S Scale 35% 75% 119% 136% 188% 211% 289%
OO Scale 30% 63% 84% 115% 158% 211% 289%
HO Scale 26% 55% 73% 87% 138% 184% 253%
TT Scale 19% 40% 53% 63% 73% 133% 183%
N Scale 14% 30% 40% 48% 54% 75% 138%
Z Scale 10% 22% 29% 35% 40% 55% 73%

Find your scale in the table along the top. Then scroll down to the desired scale and find out the factor you need to enlarge or reduce. So, if, say, I have HO scale plans I want to enlarge to O scale, I run across the top to HO, then down to O scale, and see that I need to enlarge the plans to 181%. If I have O scale plans I want to reduce to S scale, I run across the top to O and down to S, and see I need to reduce the plans to 75%.

You can also do this if a building you want exists in kit form for a different scale. Measure it. Then do the math based on the chart to figure out what size to build everything for your scale of choice.

Further reading

I hope you find this model railroad scale conversion chart useful.

On a somewhat related note, if you’re unsure what scale something is, here’s how to figure that out before you convert it. You might also find my cross-hobby scale conversion helpful.