After trying out any number of different commercially recommended palettes, I have come to the conclusion that melamine is the only surface perfect for watermedia. Watercolour cleans off under the tap (hot water works faster than cold). If I've used any staining colours, I rub those areas with a creamy cleaner (do not use abbrasives!) to finish the job, then rinse off with a washing up liquid to make sure there is no grease on the palette. Acrylics clean off by soaking the palette, preferably in hot water, for a bit, then the old paint simply flakes off. Use a plastic palette knife or other non-scratching tool if you find that easier.
Later that day. I was going to clear all the paint off, but under hot running water the in-between bits washed off leaving so much usable paint that I decided to carry on using it. You can see from this photo that the paints are now clean and ready to use again. The shadow is me taking the photo!
|cleaned up melamine tray|
The palette in these photos is a large white melamine tray. I have two of them. When one of them gets out of control (like in the first photo!) I start the second one and use any paints still usable on the first tray before washing it clean at the end of that session. The advantage of using a tray is that it has raised sides. Before painting, colours have to be reactivated. I use a water spray. The raised edges prevent any paint going off at a tangent. The tray is left in a flat position, of course. Otherwise the colours would run into each other, which is not the same as mixing them intentionally!
You can, of course, paint without using a palette at all. Especially for oil glazes this is quite a good idea. But painting acrylic straight out of tubes or bottles is probably unwise, as the paint dries fast and would deteriorate very quickly.