I paint in watercolor. I like to squeeze tube paint into a palette and let it dry. I label the side with the name of the color and the lip with a T for Transparent, S for Semi-Transparent and an O for Opaque (but I try not to use opaque colors). I use a Sharpie marker. If you make a mistake or replace one color with a new color, simply swab it with a bit of nail polish remover. Let it dry and then you can relabel it.
But have you ever put a color in your palette that you don't want there anymore? Or perhaps you have used almost all of it up, and you want to put fresh color in there or a different brand in that spot? Maimeri Blu used to have a gorgeous Sap Green. But then they couldn't get quality pigment any longer for the color, so they discontinued it. I have been trying other brands of Sap Green and so far no luck in finding a replacement. So, now I have Sap Green in the slot where I do not want it. What to do?
1. Wet the edges with clean water on a brush, scrub around the edges just a little.
2. Use a palette knife and work it under all around the edge on all sides.
3. Work the palette knife under the base and grip the wad of paint with your thumb.
4. Using your fingers, pull the lump of paint out of the palette square.
5. Voila ... the square is now empty, the paint has been removed.
6. Swash a wet paint brush around, scrubbing a bit to loosen up any remaining bits.
7. Wipe out with a damp sea sponge.
8. Now you have a clean empty square to fill with fresh paint.
9. I place the paint I have removed in my scrap palette, a simple butcher's tray.
Waste not want not! :)