Homebrew PCBs

I'm using a brand of positive board that surely does not exist in the
US. I live in Spain. It is green.

Yesterday I did some tests, and photoresist SURELY goes out it I try
to clean it. I need to wash it with fresh water then let it dry a bit.
Else, all I touch fades away... I tried for several exposure times. It
seems that more time, more resist... but not sure. Not very clear
evidence...
I really don't know what to think or what to do!