DONNA saliva tester

Hi everyone.

I just purchased a DONNA saliva tester over e-bay and have been looking over past posts to find out some info on them, i think it works the same way as maybe baby.

I have seen alot the girls in other posts say to leave it to dry for over an hour, but what i would like to know is can the result fade or change with the longer you leave it, like opk or hpt it says that the result should not be read after 10 mins as it can give false +'s, i was just wondering if the result of the ferns could change over time aswell or do they stay the same once they are dry?

I have never heard of the Donna one, is it the same sort of thing as the Maybe Baby??
I know with Maybe Baby it doesn't matter what time you read it as long as its dry.