Most Helpful Guy
Oil paint is not water-soluble, as I'm sure you are aware. I use turpentine to thin it when painting, and also to wash brushes. You can also use methylated spirit, but it's not as effective. Cleaning palettes I also use turpentine, but you can't pour that down the drain as it is very bad for the environment (it contains CFCs and insoluble chemicals that seriously damage aquatic ecosystems). Store used turps in a sealed jar or bottle and dispose at a recognised disposal site, like a local recycling centre. Use kitchen roll to clean up palettes and a little turps to wash off what you can't remove with kitchen roll. Oils are very slow to dry, so you can work different shades of colour into the area's you have just applied, and blend them on the paper/card/canvas without mixing first if you like. Hope this helps!