While the results shown are OK, you can achieve as good a result with inexpensive c/c powder, I think everyone has a standard and sometimes what one person reckons is a fantastic result, a more pedantic, or fussy individual might find fault with it.
I would, however encourage everyone to try everything, as what works for one, won't necessarily work for another.
I used a product years ago which reacted in the way Steve suggests, but the manufacturers said this would happen, when water was reapplied.
Concerned me, at first, but the results were excellent.
