Screen E-Book (.PDF) - MacDermid Autotype

Over the years we’ve built up a large numberof case studies of problems found inthe real world. Here we share our experienceof the things that have caused screenprinters real problems – and the solutionswe have found for those problems.DirtDirt obviously can mess up your print inmany ways. Dirt on the mesh during coatingcan cause streaks. Dirt on film positiveor on the stencil during exposure cancause pinholes. Dirt during printing givespinholes and streaks.The highest quality screen printers dotheir work in cleanrooms. It’s amazing howmuch easier life is when you don’t have tofight with dirt. If you don’t have the luxuryof a cleanroom then here are tips we’vefound make a real difference.1.- Install a simple filter in the water supplyused for your stencils and meshes – andremember to change it regularly. It costsa few cents yet can save large amounts ofmoney in avoidable rework.2.- Clean all surfaces and floor. Use adamp cloth or vacuum with a HEPA filteredexhaust.3.- Close doors and use tack mats to minimisedust and dirt entering the screenprinting area. Also minimise the numberof people moving around in the area.People are the biggest source of dust. Ifadding additional enclosure take care thatair movement into the area is from a cleansource. For instance shutting the door willbe a waste of time if the air is then goingto be pulled from a dirty air space aboveceiling tiles.4.- Use lint free wipes5.- Avoid fibrous packaging, sheets shouldbe removed from the transit box prior touse. Card and paper should be kept awayfrom the printing area if possible.6.- Raise humidity (this reduces static). Ifyou damp down the floors, take care toavoid slip hazards7.- Wear clean room overalls8.- Filter air conditioning. If you turn off airconditioning on days that it is not necessary,make sure that the alternative sourceof air is not dust laden.9.- Use an ionising air-gun to clean yourmesh. An ordinary air-gun can create static(yes, we’ve measured the effect) and attractdirt back onto the mesh. The ionisingair gives a really clean result.Static controlStatic causes dust to be attracted to surfaces.It is produced in 3 ways1. Separation2. Friction3. Induction73