I you use acrylic paint, you don't really need to varnish it for protection. It is quite tough. Acrylic varnish is basically clear paint, so it will add a bit of gloss to the finish but a wax polish is really all that's needed.
Mouldings with a overall flat colour are a pain. Any slight flaw will stick out like a sore thumb and are next to impossible to touch up successfully.
Hand-finishing the same finishes also has the same problems. Try painting a frame flat white.
You need coats and coats to get a satisfactory result. But at least you
can fix dings and scrapes perfectly.
Spraying is a better option for flat colours. If you have the kit and the space.
Speaking of which..... There are some cheapo mouldings that make an excellent base for cellulose (car) paints. No heavy prep - just de-grease the surface and put on a couple of light coats. I used loads of the good ol' black cushion like this at one time. The solvent etches into the surface and gives a very good bond. The metallic finishes look very classy. Doesn't work on all mouldings though. Try and see is the key.
The beauty is, you can cut and join the frame before spraying. It matters not if big chunks get chipped off the corners - make good with filler and sand down and after spraying for perfect corners. This would probably take less time than arsing about touching up corners on a pre-finished moulding.
If the frame gets a scrape ( the finish is surprisingly durable) then it can be resprayed.
Maybe not worth it on a little frame, but on a big one it could save ££££s
Not everybody's cup of tea. If you were doing a lot of frames a dedicated spray area would be needed. Overspray gets everywhere. Spray cans are OK for doing a few frames now and then, but ideally you need to source the paint in tins from an auto paint supplier and get a spraygun. (and compressor - although most framers probably have one and if you haven't you don't need a big one).
