There used to be an earlier version of this topic.
In it I suggested that the new user start out by going to the toy store and buying a plastic toy AR/tommygun/etc. Degrease it thoroughly and start practicing.
When you're done, and you want to start over with a clean slate; simply put the toy gun in a trash bag. Add some of
this stuff, bleed out the air, seal the bag and leave it overnight. The next day, take out the toy, let it drain into the bag, and wipe it down with a wet sponge. Hose off any remainder. The degreaser should have completely loosened the rattle can paint, and the toy should now be a clean canvas. This way you can perfect your techniques without doing anything that threatens your real rifle.
I know this Castro Super Clean stuff works great with rattle can camo paints, and it's even supposed to be biodegradable. You can recover the used degreaser by straining it through some cheese cloth back into the jug, and use it again over and over. I've only ever used it straight from the gallon jug.
You'll probably decide, as I did, that rattle can paints simply show the wear too quickly. When you do, the Castro Super Clean can strip it off pretty effectively. Just be really careful with optical coatings, etc.
I've often wondered how well it might work in the bore for carbon rings, etc... But I'm not quite ready to be the guinea pig on that front just yet... The stuff is impressive; I use it as a low-toxicity paint stripper.
I'm not saying anything about whether it works with the more durable coatings, I simply don't know. I do know that it will attack exposed aluminum, taking the shine right off overnight. Maybe that's a plus.
If you're working with masking tape and you want a softer line, raise the edge that establishes the border, and spray paint it
LIGHTLY at a right angle to the surface, less is better.
I'd done a lot of research into the science behind color, lighting, and how it all best applies to camo. I reduced it down to a set of base colors using three shades of gray, with color tints added to adjust the color scheme to the local environment. Dark colors work poorly and stand out; most beginners forget that the rifle will probably be getting used in shaded areas providing cover, and that they need to be lighter to take the shadow and still look realistic. I tended toward something I ended up calling 'shark-flage'; incorporating the base grays with the darkest shade atop, the medium shade alongside, and the lightest on bottom. This adjusted the colors so they more closely resembled the lighting effects on the surrounding shaded environment.
This can all get pretty complex, but in the end, I threw about half of it out the window and went with large, more indistinct shapes, much as Uncle Sugar had already perfected long before me. I discarded those small intricate details because, simply, they cannot be resolved by the eye at any serious distance.
IMO, in nature, snakes do it best.
Greg
I once had a chance to visit the USMC RTE (Rifle Team Equipment) Shop at Quantico at the Garand Road compound back in the mid-1990's. They had a newly completed M40 that was ready for issue to a new Scout Sniper. It had been sent out to a retired 8541, and he had done a custom woodland camo job on it using Polane(?) and an Air Brush. It was a true work of art, and the thing that especially caught my eye was the tiny subtle highlights with a light spring(?) shade of green.
I think that all camo is local and that the Operator needs to be capable of redoing their camo on their own; things change a lot, and often.
I toyed with the idea of a two layer camo, with a near impervious epoxy under layer of the grays, repeatedly being touched up to reflect changing local camo needs using a translucent acrylic top layer that could be stripped periodically using the Castro Super Clean. I would use a low luster acrylic floor wax as the top coat medium, tinted with acrylic enamels. I never got to actually try it.