I run across all kinds of shops as a sales rep here at Texsource. Some shop owners quite picky about the cleanliness and efficiency of their shop. They will meticulously care for their screen printing equipment, keep their supplies and ink in careful order and detail, and insist that the entire shop be cared for and maintained to almost military standards.
Those types of shops are not the norm. Most shops run at such a frantic pace that maintaining a certain aesthetic is a luxurious afterthought. It is in such shops that many screens and frames find their way to what I call screen 'purgatory' - it is a section of the shop where screens don't necessarily go to die, but they sit on a shelf (or in the floor) covered in ink, emulsion, perhaps some other chemicals, and so forth (you get the idea). It is here that some may sit for days, weeks, even months or longer. When they finally get around to getting a proper cleaning, some owners wonder why they have ghosting and haze issues. It does make you wonder....
Several months ago, Dwayne here did an excellent video where he demonstrated cleaning an aluminum frame that was being used in our filtration system. I think that it bears reposting that video here so that you can see what I am talking about before I go any further, so here it is.
Here, Dwayne is using two of our more popular products for screen reclaim, Easiway 701 and EasiStrip. One works as an emulsion remover and the other as a screen printing ink degradent and degreaser. Notice that key here is the proper use of your cleaning sponge. I see many shops leave this out and want the pressure washer to do all the work. With a very light scrub you can see that this screen is ready to be used again right out of the booth.
But this isn't a direct example of a screen that has sat and dried for a long period of time as I had first described. Although the above mentioned Easiway products would likely work just fine for that, you may find stains that simply refuse to be removed. For that i would recommend what is perhaps the strongest product we sell for such a purpose, the Rhino 2800 Ghost Remover. You can utilize about a 50-cent piece size blob on your screen and spread around the problem area. This product is strong, and has worked on some of the toughest problems possible that I have seen in shops. Since you only use such a small amount, the product will last you quite a long time.
So there you have it, some solutions and easy to see techniques for getting the very toughest screens reclaimed and ready to use in your shop again. Although I certainly hope that you never see such difficulties in your shop, it is nice to know that here at Texsource we stand ready to help you with even the most difficult shop issues with the right equipment, supplies, and perhaps most importantly support and service for any needs.