I thought it was the reaction of the ink with the salt so I prepared another piece, painted with gesso then Quink ink and sprinkled with coarse sea salt. Nothing happened!! Maybe it was the reaction of the Pumice Gel Medium with the salt and the ink just highlighted the effect. I shall have to try again as I think it looks really good.
When the ink was dry I used a rubber stamp I had carved some time ago. Painted the stamp with bleach and pressed it on the surface. I then used a bleach pen to lightly brush over the rest of the piece.
What I find amazing is that this stamp is just carved in the outline of a lizard, taken from a painting by Escher. It is totally smooth and yet the bleach effect has made it look like this lizard has two eyes!
I am going to work further into this and actually make it into something, possibly a book cover. I will post photos when I have finished it.