I see where some people use Rosco filters for enlarging. What are people's experience using Rosco filters, and how long do they stand up? How stable are they, before they begin to vary in contrast filtration? Put another way, what are their fading characteristics? How consistent are they sheet to sheet? For example, if one purchases another sheet down the road, can they expect to get the same contrast they did when starting to use the previous sheet? If stored in a dark area, do they retain their color well? I have a Zone VI 8x10 type ii non variable contrast head, and i was thinking of using Rosco filters for VC printing. I hesitate to think what regular acetate filters would cost of an 8x10 head.