after deciding on the colors you want to mix, squeeze out from tubes onto a piece of glass or a white plate and mix with a pallet knife thoroughly, you will likely need to test and adjust while mixing so the amount could easily become larger than you first wanted , have an extra pan ready,

Say I wanted to mix blue and yellow to make a special shade of green and use it later. Which approach is better?

1. Mixing some blue and some yellow from tubes into a half pan?
2. Mix the colors with a brush on a blank mixing well of the palette?

If number 2 is the best way how do i reuse it? Just let it dry on the palette mixing area? Any way to get this into a half pan for later usage?

Thanks.

If you want to mix up a special color combo and then put it into a half pan, you can squeeze color A onto the palette, then add color B, make up your mix and use a palette knife to scoop it into the half pan. You could also just scoop it into an empty palette well.

I think if you squirt color A into the half pan and then color B, trying to mix it together with a toothpick, you might not be able to mix it up completely. Also you won’t really know what your mix looks like until you paint with it.

If you mix A and B on the palette and don’t use it all, you can just mist it with a spray bottle and it will reactivate, the same way a dried blob of tube paint does.

A third option for color mixing is to mix on the paper while you are painting. If you want to make greens for foliage etc, you can put down a nice wet yellow wash, and then drop in your blues. The blue will spread out into the wet wash and the colors will mix themselves magically on the page.

If it’s greens in particular you are thinking of, here are a few nice references:

https://shariblaukopf.com/2018/12/19/mixing-greens-a-preview/

https://shariblaukopf.com/2015/06/07/variety-in-greens/

https://shariblaukopf.com/2015/10/01/my-current-palette-and-some-green-mixes/

There are many recipes for different green mixes and a few rules of thumb:

1) Try to keep them varied by constantly adjusting the ratios of blue to yellow; use reds to dull them down, yellows to warm and brighten. Otherwise you get kind of this monolithic “wall of green” that’s all one color/tone and it can overpower your painting and distract from the main subject.

2) Unless you are painting an alien spaceship or a green traffic light, Phthalo Green straight from the tube is pretty garish. You can use it to mix a nice black with Aliz. Crimson, or to mix beautiful turquoises, or very very bright greens, but there are no greens in nature that looks like Phthalo Green straight up.

3) If you mix a lemony yellow with a greenish blue, you will get a nice bright green. If you mix an orangey yellow with a purplish blue, you will get a dull green. If your green mix is over bright, you can add a bit of red to calm it down. If it’s too dull, you can add yellow to brighten it up.

Color mixing is part art, part science. It takes a lot of experimenting to get the hang of it, but luckily it’s really fun and very magical and mesmerizing.

Good luck with your attempts.

Here’s an example of making a custom mix by putting two colors into the same half pan:
https://janeblundellart.blogspot.com/2014/02/custom-made-watercolour-mixes-janes-grey.html