I use old piece of marble that I found in the yard, it is small. 15 by 30 cm appx. I scrape first, then old rag wipe, then a bit of solvent. Marble is porous so color is quite grey-blue-orange-pink-etc. It does not bother me at all. Main that it does not move and sits well on the table when I paint. My wooden pallet was wiped with linseed oil while it was new. So oil adsorbed and polymerized. I did it couple of times and not it is quite easy to clean. Also scratch and wipe method. Main criteria it does not stain things around when i am done with painting. Sometimes color sit on the pallet for a week or so ( in the freezer) they dry out a bit and scratching part becomes a challenge, but still fun as I see such wonderful abstract paintings there, the ones i cannot create in the conscious way 🙂