Painting canopies

Why does every wargamer, including me, no matter what scale he or she is working in, seem to endlessly agonize over what color to paint canopies and windows in aircraft? I guess because we know that in reality they're clear glass (ok, not really glass per se, but you know what I mean) and there's just no good way to make solid resin or metal seem clear.

So how do we do the best we can at depicting glass using only paint? What color(s) should a miniature canopy be? Well, the first question to ask is what color is a real canopy (apart from "clear")? Not wanting to get too technical or scientific, because it all has to do with the geometry of light and reflection, I'll just say that it really depends on the shape of the canopy, how much surface area the canopy has in relation to the rest of the fuselage near it, and from what angle you view it. If you view a canopy from more or less 90°, i.e. side-on, you'll look right through it and see the sky on the other side:

So it will appear light-colored. This is enhanced if the canopy has a relatively large surface area, as it makes the sides of the aircraft seem smaller by comparison:

However, if you view the canopy from any other angle, you'll be looking into the interior of the cockpit, which will be heavily shadowed, rather than through it:

This makes the canopy appear dark:

So we have a choice; paint light or paint dark. If we paint light, it's correct from one angle and wrong from every other. If we paint dark, it's correct from every angle, save one. But of course, wargaming isn't always about slavish adherence to reality. Sometimes things can be perfectly correct, but they just don't look right. In the end, it's merely a personal choice. If something looks good to the painter, it is therefore good. 

I have tried both methods and to me, the dark style looks less...cartoonish, but I find that if the aircraft already has a dark-colored paint scheme, a dark canopy can get "lost" and be very difficult to differentiate from the rest of the aircraft. As I've been painting a West German Alpha Jet today, I gave it a very dark grey canopy to show you the problem:

See? Very indistinct (I'll repaint the canopy, don't worry). To try to remedy this, I normally use a middle grey (Vallejo Dark Sea Grey 991), followed by a gunmetal wash (Vallejo Gunmetal Grey 863). This slightly silvery look makes it easier for the eye to pick out the extent of the canopy and gives a bit of an illusion of "reflection". No matter whether the aircraft's finish is matt or satin, I always finish by giving the canopy a gloss coating. 

I'm not saying that my way is the "right" way. It may not even be the best way, but it's one way. If you do it differently, I'd love to know so I can give it a try too. I'll do a post on the Alpha Jets (and the canopies) as soon as they're finished.