Tech Tips

Masking Canopies

by Frank Spahr

Masking - Aaargh!

I read a posting titled as above of these days at this site's message forum, and it pretty well

sums up my feelings to this point. Masking is tricky, tedious, unnerving and often not quite

predictable. Any modeller has to face masking problems now and then, so I´d like to sum up

what I´ve learned about this issue.

We have either to mask parts that should not be touched by paint at all, or areas of different

color on a model. For me, being a World War II air modeller, the former category is

concentrated to aircraft canopies. Coincidentally, in the WW2 era the use of blown single-piece

plexiglas canopies only began, and most aircraft had greenhouse-like construction often

consisting of fifty or more single panes. Naturally the modeller has to spend a lot of time

masking canopies.

What can be achieved. Don't be fooled by the fine detail - this "Beaufreighter" (transport conversion of the Bristol

Beaufort torpedo bomber) model is in 1/72 scale!

The canopy is crystal-clear (vacuum-formed in this case), perfectly blended into the fuselage contours and features

crisp, carefully aligned framing. Model by Victor Krogius.

Photo: Peter Alsterberg.

Demarcation lines between different colors can vary in sharpness. For example, the British

wartime camouflage schemes used sharp edges through and through, whereas most German and

some American schemes (notably the USN tricolor scheme) were sprayed freehand, resulting in

feathered edges. National insignia, D-Day Invasion or Reich Defense stripes, walking area

markings and the like had sharp edges. These stripes are frequently added to kits as decals,

but... well, I at least haven´t produced a decent Reich Defense band yet by using a decal.

Techniques for masking canopies described below will naturally suite all other applications

where a sharp color edge is desired.

To begin with, any means for masking has to fulfil the following requests:

1. It has to adhere to the surface closely

2. It must be adaptable to curved, recessed or otherwise irregular surfaces

3. It has to stick firmly to the surface, yet must be removed without damage to the

underlying paint

4. It has to provide a sharp demarcation line

5. It's use should not damage surface detail

Brush-painting

When I built my Airfix kits as a kid, I used Tesa

film for masking, a transparent sticky tape for

office use. I don´t know how it is called in

Sweden (I believe the most internationally

known brand this side of the Atlantic is Scotch

tape - Ed.). It tended to work as a paint remover

on the masked off area, which would be OK for

canopy masking, and that it was not at all

flexible, so it couldn't be applied to curved

surfaces. Consequently, the waterlines on my

battleships were fine amidships yet degraded

especially towards the stern. I didn´t even

consider painting the cockpit greenhouses then

...

As a returning modeller, I brush-painted the first new kits I built. I used a very fine brush and

steeeeeeady hand for canopy frames. To be honest that part of the work was hair-raising, and I

never managed to avoid some paint getting on the window panes.

Removing the paint overflow is not very difficult. I used a wooden toothpick for the purpose,

since the comparatively soft wood wouldn´t leave scratches on the clear plastic surface.

Further troubleshooting on canopies works best with the following sequence:

• wet sanding with paper grit #600-1000

• fine polishing paste applied and polished with a Q-tip (I use the dentist's Ivoclar

polishing paste)

• buffing with a Q-tip or cotton cloth

Despite my efforts, I was never really happy with the brush-painted results, since they couldn't

The beginning. Although it is possible to obtain

good results solely by hand-brushing, the

technique has many pitfalls.

be made uniform and thin at the same time. So I bought an airbrush which made other solutions

necessary.

Tapes and Liquid Masks

Experimenting began with very narrow adhesive

strips used in electronics. These could be

adapted very well, removed without damage,

but sometimes they wouldn't stick tight enough

and the borders tended to be blurred. Moreover,

you had to mask the area next to the strip to

prevent overspray. That was when I first used

Humbrol Maskol or Revell Color Stop. This

silicone goo flows into any irregular surface and

leaves a sharp demarcation line, yet not a

straight one. I used it with my canopies,

applying it meticulously with a toothpick.

The results were only partially satisfying. As I already mentioned, the main problem remained

getting the straight edges.

Parafilm M

Next came the Parafilm M. Well, that was a big

improvement. Parafilm is a stretchable foil

designed for laboratory purposes, mainly for

sealing test tubes and the like. It adheres to a

surface in just the right degree, so it sits firm,

but doesn´t tear the paint off. It can be adapted

to any surface, and be cut to size allowing for

easy masking of enough surrounding surface to

prevent overspray.

Using Parafilm needs a bit of learning, but it

pays off greatly. You stretch a conveniently-

sized piece of the foil. pre-stretch it and adapt it

to the surface, say the canopy or the fuselage. Then you´ll need a fresh X-Acto blade and some

patience to cut out all the framing of the canopy. Unwanted pieces are then lifted off and

removed with the tip of your X-Acto blade, leaving only the panes masked.

Humbrol Maskol. Using Q-tip as an applicator tool

is a good idea as Maskol would permanently clog

any brush used for the purpose.

Before use, Parafilm M should be stretched in one

direction to about 2-3 times it's original length

The canopy frames of the B-25 above were masked using Parafilm only. Model by the author.

Photo: Frank Spahr

This method leaves absolutely crisp borders. I also don´t think it is more time-consuming than

other methods. It's disadvantages are that damage my be done to the surface by cutting and that

it's hard to obtain straight lines without a flexible ruler.

E-Z Masks

In an earlier article, I mentioned the trouble with the canopy of my my ProModeler Me 410.

The transparent styrene is more vulnerable to cracks than the solid one, and when you have

minute cracks filled with paint, you can forget the part.

The complex shape of the 410's canopy, especially the rear gunner´s compartment with its

bulges, would make cutting the Parafilm M masks a very tedious task, so I ordered my first E-Z

Masks. I had to interrupt my work on the 410 for several weeks. Now, after having done it, I

can say that it was worth the wait. Using E-Z Masks is a lot easier than all the other methods

described above.

What the modeller gets are two sheets of pre-cut

vinyl, a red one for the inside and a blue one for the

outside. Tricky parts are included twice, as well as

some pre-cut strips for emergencies- very

thoughtful! The parts for the bulged windows were

cut in several parts, so that you could start with the

edges and patch the middle afterwards. The vinyl is

rather sticky, firm, yet somewhat deformable so it

adapts to the curvatures. I regard it as a very fine

material and I´m wondering whether you could get

it in uncut sheets for custom-making masks.

The set for the 410 had just two flaws. Whereas the

inside masks were absolutely correct and a joy to

E-Z Masks at work. The Me-410 canopy parts

have been covered with pre-cut masks and are

ready for painting.

work with, some of the parts for the outside weren´t cut correctly, so that you only had one part

where two or three individual parts were necessary, especially for the access hatches. This can

be remedied by measuring on the canopy and pre-cutting before application. It should be added

that I recently read Scott van Aken´s report on the 410 in which he stated that this feature was

intended, since the framing was partly only on the inside of the canopy. I couldn't confirm this,

so all my canopy frames are double-sided.

My second objection is that the metal plate around the antenna hasn´t been reckoned with, but

that is easily corrected.

Summarising, I regard E-Z Masks for a very helpful aftermarket offer, much recommended.

However, a word of caution. I removed the E-Z Masks about 3 weeks after masking the canopy.

It was hard work! It was considerably harder to do than removing the inner masks, which I did

directly after painting. I don´t know whether anyone else has experienced that. I was lucky not

to damage anything, since I normally glue the canopies with Kristal Kleer, and only in this case,

due to poor fit, had I used cyanoacrylate for fixing those stubborn parts together.

Having sprayed the canopy, I mused about the Reich Defense band. It should be red and

yellow, and obviously using the decal would spoil much of the work I have put into this project.

So I took the remaining "emergency" strips from the E-Z Mask to mask the fore and aft

demarcation of the stripe. It worked out beautifully. I also masked off the adjacent parts of the

plane with a very simple method, using the plastic film you use for preserving food. I wrapped

it around the model and sealed it at the vinyl strip with Humbrol Maskol. Quick, secure, cheap

and easy.

Well then, my Maskol must have dried by now, so I´ll continue ...

Pretty view, uh? This Reich's Defense band was masked using three different materials, as described in text.

Photo: Frank Spahr