You CAN NOT submerge them in mineral oil/water though - the labels will fall off!! ** I learned the hard way, I submerged mine in a bowl for 30 sec to a minute to get 25 chips oiled real quick, ALL labels came off those chips. I used a micro fiber cloth and applied the mineral oil to the cloth - then wipe down each chip, they it soak in for a while, then buff off the rest of the oil. The chips colors pop after this process.
That being said, I did this to half of my chips before my poker night, I simply ran out of time, so my 25 & 100 tournament chips did not get oiled. After the night was over, the oils from the players hands changed the colors drastically, I didn't expect this. Because of this, I will not be fishing the other 800 chips I still need to do - too much work! lol
Good luck!