i use the cyanotype II from www.alternativephotography.com and have a qs.
Last weekend i did my first cyanotypes and found out that when washing the picture looks very beautifull blue, but after an hour of washing it turns more to light blue while the area around it where no negative as still is much more blue.

Do i have to overexpose the image so that after washing i get the beautifull blue?

I did with the washing at some wetting agent for 5 minutes and after that 30 minutes of normal water wash. Could this be the problem?