Screen Preparation: A Cornerstone For Successful Screen Printing

International Sign Assoc.


Matrix Payment Systems


SGIA Specialty Graphics Imaging Assoc


Mesh showing clean surfaces


Despite the fact that mesh manufacturers give their completed mesh a very good cleansing after it's woven and set, rolled mesh gets handled in packing and transport at the distributor location, and once more at your manufacturing facility when the mesh is obtained and stretched. All of this dealing with leaves greasy residues, mud, and dirt on the mesh, any of which might interfere with stencil adhesion, and contribute to premature stencil breakdown. Proper preparation of the mesh is a cheap approach to stop fisheyes, pinholes, and premature stencil breakdown. Mesh preparation is damaged down into two key steps: Abrading and degreasing. Abrading is used solely with stencil films, and not liquid-direct emulsions. But note, every display screen must be degreased.
Apply abrader with delicate bristle brush.


Abrading
Abraders come in powder, paste and gel types. Modern polyester mesh threads are extruded (similar to fishing line), and are slick and clean so stencil films don't adhere readily. Abrading the mesh will increase the surface space on the knuckles for higher gripping by the stencil film. Abraders are fantastic silicon carbide micro-grit preparations. Surprisingly, regardless of their effectiveness, they don’t feel rough when rubbed between your fingers! It's because the particles are so effective. Abrading the mesh is accomplished by making use of a small quantity of mesh abrader onto the substrate or print side of the mesh with a smooth brush, and evenly scrubbing it. Abraders do not need to face on the screen. Will be rinsed off immediately with a firm strain spray. Effective mesh abraders embody Autotype Autoprep paste and Ulano #2 Microgrit powder. Don't use household scouring powder to abrade your mesh! Despite the fact that Comet® or SoftScrub® costs $2 as a substitute of $20, these family cleaning products are too abrasive, and assured to shred the surface of your costly mesh. This will scale back the screens’ life and go away lots of deep gashes and pits the place ink and emulsion can accumulate and grow to be lodged, thereby growing staining, ghosting and hazing problems within the screen. Even with the correct product, testing on the Screen Printing Technical Foundation (SPTF) has shown extreme abrading will cut back screen life. The perfect advice is to do it once when the mesh is brand new, then once more if essential after 5 or 6 stencils.
Mesh abraded with scouring powder


Degreasing
Mesh Prep Rule #1: Degrease each display screen you ever make for so long as you reside! Degreasers are damaged down into two primary categories: these with wetting brokers and people with out. The simplest strategy to see in case your degreaser has a wetting agent is to degrease one half of a display screen and evaluate how the 2 sides hold water. Apply the degreaser in question to the precise half of a screen and go away the opposite half untouched. Scrub the degreaser well into the mesh, and depart it to stand for a minute or two. Then flood rinse the screen, and hold the mesh at an angle until you'll be able to see if the mesh holds water. A degreaser with a wetting agent will leave a smooth, even, glossy sheet of water across the mesh, in comparison with the management side the place droplets and rivulets type and run off without sheeting. Degreasers without wetting agents are designed to be used with liquid-direct stencil emulsions. They're designed to remove dirt and greasy residues left by inks and ink cleaners. Some examples of in style degreasers with out wetting agents include Ulano #three Degreaser, Ulano #33 Degreaser Concentrate, Chemical Consultants (ICC) Nutralyze, CPS Degreaser Concentrate, Chromaline Chroma/Clean Mesh Degreaser, Fujifilm Sericol Xtend XMP-HD (Heavy Duty), KIWO Degreaser 1:20 (sturdy foaming action) and 1:40 (diminished foaming). Wetting brokers are essential for a stencil film’s good adhesion, though many stencil technicians report that in addition they enhance its coating potential for liquid emulsions. With stencil film, you need to use both a degreaser with a wetting agent or separate degreaser and wetting agent. Generally, if water sheets smoothly across the mesh, even liquid emulsions with about 60 p.c water will move and sheet better. If water is repelled from the screen mesh, it'll movement in little rivulets and form droplets on the mesh. Degreasers with wetting brokers include Autotype Universal Mesh Prep, Fujifilm Sericol Xtend XMP-AC (Aqua Coat), Ulano Magic Mesh Prep, KIWO Dual Prep, Easiway Mesh Preparation, Chemical Consultants Liqua-Prep and Prep-Rite and the new KIWO Ultra Prep. Some manufacturers make a wetting agent separate from the degreaser, resembling Ulano #25 All Mesh Prep and Chromaline Chroma/Wet Wetting Agent. Some degreasers — corresponding to CPS Degreaser Concentrate, Ulano Magic Mesh Prep, and KIWO Ultra Prep — contain anti-static additives to help stop the screens from attracting mud. This could significantly cut back pinhole problems attributable to mud and dirt.


Damaged mesh from abrasion.


Household dish detergents aren't efficient screen degreasers as a result of most manufacturers contain lanolin or wool grease, which keep human skin from drying out whereas doing the dishes. These additives leave greasy films. Contaminants on the display screen mesh. However, for computerized degreasing gear techniques, non-foaming detergents can be used as effective degreasers. While it is best to seek the advice of a detergent specialist for suggestions, I've seen each laundry powders and computerized dish detergents used with various degrees of success. For those who abrade or degrease several screens in a row, the preliminary display will have been left to stand lengthy enough and ought to be prepared for rinsing by the time you have degreased the ultimate screen. Rinse generously, as any remaining detergent or abrader on the mesh will act as a contaminant!
Undegreased mesh.


Combination degreasing and abrading
Mesh abraders and degreasers sometimes are combined into one product. Examples include Ulano #23 Roughening/Degreaser Gel, Chromaline Chroma/Brade Mesh Abrader/Degreaser gel and Chemical Consultants Ads-301 Abrader/Degreaser/Stain Remover. Sometimes caustic or etching degreasers and abraders also can be utilized, resembling Autotype Autopaste and KIWO Pregan NT Paste. These alkaline products are significantly efficient with mesh that's heavily stained with ink and emulsion residues. Some firms, corresponding to Intercontinental Chemical Co. (ICC), incorporate an alkaline degreaser into the haze remover. Since these products finely etch the mesh, it is very important follow the manufacturer’s tips for dwell time when using alkali degreasers. (Sodium hydroxide and/or potassium hydroxide also are found in many ghost, haze and stain removers.) In my early days as a display screen maker, I vividly recall being proven how one can degrease with the caustic degreaser, and then neutralize the mesh with an answer of glacial acetic acid! I’m not sure that I would accept the same meshes as properly prepared today, but now it is certainly simpler and less dangerous to use trendy mesh preparation brokers.
Screen degreased with out wetting agent.


Other Products and Chemicals in Screen Preparation
Bleach is still occasionally used as an emulsion remover, or more successfully as a diazo stain remover. To take away diazo stains from underexposed stencils, bleach will be brushed onto dry mesh and allowed to dry — before being flood rinsed — after which pressure washed to take away any traces of stain and chemical. Excessive use of bleach can have an effect on some of the anti-halation dyes used on colored meshes. The identical means that bleach can finally damage your jeans, it can even damage or embrittle your mesh. Also, ventilation programs are crucial if bleach is used in your display preparation area. Tri sodium phosphate has previously been used as a mix degreaser and abrader. However, it is de facto too abrasive for display mesh, and it doesn't degrease in addition to proper screen degreasers, so screen technicians are suggested to pick out fit-for-purpose mesh preparation merchandise. Abrasive furnishings polishes — comparable to Rottenstone (a soft decomposed limestone) and pumice (a lightweight rock of volcanic origin that is used to scrub calluses and soften the toes) — are too abrasive on your expensive screen mesh, so remove these merchandise when implementing industry finest practices. Commercial grill and ground degreasers can be used on screen coustic mesh with varying degrees of success. Test rigorously to make sure there are no residues or contaminants remaining. Liquid Plumber®, Drano®, Red Devil® Lye crystals and different drain openers are corrosive merchandise designed for industrial filter mesh the elimination of clogs from household drains. They aren't protected to be used on screens. Don’t use them.
Screen degreased with wetting agent.


Popular multipurpose household cleaners such as Simple Green, Window Cleaner and Orange Spray & Wipe Cleaners (often containing 5 percent to 15 percent d-Limonene) additionally leave too much residue on screens and should not be used for cleansing or degreasing screen mesh. If you have any type of inquiries regarding where and how you can use Screen printing mesh dealer, you could contact us at the page. Straight d-Limonene by itself isn't water miscible so it isn't an efficient mesh degreaser. However, it may be blended with surfactant packages to make it water dilutable and rinseable. Then, it can be effective as a frame degreaser, though it's not really useful for degreasing screen mesh. D-Limonene is pressed. Steam distilled from orange peels. Because it smells like oranges, folks can sometimes assume that it is a completely protected product, when actually it may well de-fats the skin. Safety gloves and store glasses should be used, simply as with another industrial product. In Conclusion
Chemical manufacturers design a variety of products to be used in mesh preparation. Use mesh abraders solely when utilizing stencil films, reminiscent of capillary and oblique gelatin ones. All screens ought to be degreased. Degreasers with wetting agents are essential for stencil movies, but virtually any mesh degreaser can be used with liquid-direct emulsions. Mesh preparation is inexpensive and simple to overlook, but implementing a best-practices strategy will improve stencils, and decrease potential problems from contamination, fisheyes, pinholes and premature stencil breakdown. This article appeared within the SGIA Journal, 2nd Quarter 2007 Issue and is reprinted with permission. Copyright 2007 Specialty Graphic Imaging Association (www.sgia.org). All Rights Reserved.