I don’t underestimate my ability to get fundamental things wrong. Since I started modeling again I’ve used flat finish on almost everything - and now all acrylics. Certainly seems to be the mode of choice in many articles and posts, not to mention paint suggestions from kits. Have a contending opinion however. In the Osprey book “Modeling the Zero” the authors suggest gloss acrylics across the board, finishing up the kit with a combination of flat clear and gloss clear to give a “satin” finish. The idea here is that aircraft paint (at least the Japanese variety, although they don’t make that distinction) isn’t really flat. It doesn’t have the shine you’d find on a new Mercedes, but it isn’t flat. When you get down to it, they might have a point. Have I blown maybe $100 on Tamiya, Testors and LifeColor flats in error? (If nothing else, I do have some gloss primes - might give it a shot.)
I recently finished an SBD Dauntless that had a flat dull coat for final coat… The model now currently WIP is a F4U Corsair. After reading the destructions, the aircraft has multiple versions. The marine version I believe it was is also a flat finish. The version I am building, the navy version has one to two shots of gloss coat as a final coat. It took me be surprise. I tried looking for pics and found few showing the gloss finish on a military Corsair.
Again, this may come down to a “scale effect” discussion. A model in 1/72 scale with a dead flat finish would look wrong (for want of a better word) if scaled up to full size.
A semi-gloss finish is probably a more appropriate “scale” representation of the real thing. The problem is that almost universally, the paint colours which we use for camouflage only come in a flat (matt) finish. If I recall correctly, there is only a handful of paint manufacturers who make camouflage paints in a gloss or semi-gloss.
Either way, using a gloss base and then toning down with flat and semi-gloss clear coats is more or less the same as starting with a flat base coat and then adding sheen with gloss and semi-gloss clear coats.
You can also add sheen to a flat paint by mixing clear gloss (or if available, the manufacturer’s own gloss medium) with the appropriate colour paint.
Flat paints, whether enamel or acrylic, are generally easier to control and use. I recommend doing your color work in flat (gives better hide, especially in lighter colors, than gloss.) and finishing with whatever level of gloss you think looks right. Gloss under decals, then finish with the level of gloss you think best.
“Scale gloss” would be 100 percent gloss, but that doesn’t look right except on a museum plane. “In service” would be something between semigloss and dead flat.
In the end, you are modeling for yourself so you can only answer this question for yourself. But, using gloss paints does have it advantages, you can skip the gloss coat before decalling your kit. Then add a top coat for whatever particular finish you prefer. Some military aircraft are dead flat. Some tend more towards satin or semi gloss, while others are gloss. The finish all depends upon service conditions. As said above, about the only high gloss aircraft you will see are in museums, or aerobatic teams. Nearly all others, will have a lessor degree of shine. The more exposed to the elements it is, the lower the shine will be. Even flat finished aircraft can be waxed in service in an attempt to smooth it out for more speed. On a personal note, I prefer using a topcoat of satin or semi gloss for almost all of my “shiny” builds, just because I prefer that look over the gloss finish. No you have not blown $100 on the paints you mentioned. after all, I bet many of those do not come in a gloss variety. And most likely you need to add a gloss coat before decaling anyways, so your only real question is, what final coat to use for your finish?