It's hard to put into words how Nelson's paints are different from other paints. It has something to do with adhesion and something with drying characteristics. It's very heavy in pigment and that pigment needs to be worked down onto and into the surface with a brush. It's not quite like flowing on acrylics.

Here's what I found worked well for me for painting the base color (for example the wings or fuse). First, I pour a small amount of the paint into a paper cup a little bit of Nelson's paint goes a long way. Then I had in about 1/3 as much water. Then I add a few drops of the catalyzer (for fuel proofing) and stir it up well.

I start by pretty much slopping the paint on with a 1" wide foam brush. No need to be too careful on this initial application of the paint. Sometimes there is some "beading" and the paint doesn't want to take to some small area on a first pass. Then after I've got the paint on, I start going back over the whole surface with light, smooth full length strokes working in the same direction as I initially put the paint on. And I do this several times until the paint is almost beginning to dry. You should notice a slight color shift as you go over the drying paint. You want to stop just before it starts to get tacky.

At this point it may not look perfect and there may even be some teeny bubbles from the foam brush, but somehow it always seems to dry to perfection. If there are brush strokes, I can't see them. Or perhaps it's that I can sense them and that lends an air of authenticity to the model. I can't imagine spraying on Nelson's paint but some people have done so.

Here's how my Snipe wing looked after two coats of Nelson's PC10 (with a bit of black and red mixed in to give a browner tone) and one coat of Nelson's clear.