I agree that dropping in some water reconstitutes my pans easily. Spritzing works, too. The trick is to wait the amount of time your particular brand demands; if you’re getting wimpy results, let the pigments sit with water longer.

If a particular color gives you problems, try a different brand. IMHO Winsor & Newton has more problems with drying hard and reconstituting than do other brands, and W&N appears to agree with me. W&N’s formulas for pans vs tubes have been different historically. The company has said in the past that allowing their tube paints to dry out removes some of the characteristics that make their tube paints perform well, and that their pan formulation is different in order to improve rewetting. (I’m not sure why they haven’t just changed the tube formula to be more friendly to drying in pans! Putting one’s own paints into pans is so much less expensive than is buying the commercial chiclets.)

I have some favorite W&N colors I still use, but I have switched mostly to Da Vinci, which reconstitutes beautifully and richly, with very little cracking.