I wonder how lightproof they are for darkroom purposes? The reason I wonder is that a lot of blinds/curtain shops sell so-called blackout curtains/blinds for the likes of a child's bedroom or someone working nightshifts and sleeping during the day but talking to a installer of such material, he said that they were far from darkroom standard in terms of creating total darkness for the likes of windows that were exposed to daylight
That's not to say that as a curtain for a darkroom door that isn't exposed to direct daylight or sunlight and is used for printing it won't work, just that such material may be called "blackout" curtains but be of a standard that may not be suitable for windows or be able to create total darkness
pentaxuser