"Does exactly what it says on the tin"
I bought the pens after some research because the other reviewers had complained they were indelible and would not wash off their chalk board, as I intended to use them on real slate for out door slate signs in my garden. and I can confirm they do wash off, with soapy water, so you can amend what you have written or change it. Haven’t tested if the sign will fade or wash off in the rain yet. But excellent product for makeing slate signs. Thanks