We tried this and it was kind of a flop. I still have the other pages I made but the kids just weren’t interested.
On top of that, it made a big mess.
I made several pages on cardstock then gave the kids regular watercolors that I had already added some water to. That way they had lots of good colored water to tap the salt with.
The salt didn’t stick and M didn’t understand tapping. So the salt went everywhere!
I am going to try again with the left overs but I am not optimistic.
Maybe it will work better for you.