![]() ![]() In most cases, however, printers experience haze caused by both the ink and the emulsion. If, on the other hand, you’ve determined that emulsion is the only cause of your haze, you may not need to use a solvent activator with your haze remover in the case where two-part haze removers are used, thereby saving you time and money. If you determine that ink is the only cause of your haze, you may be able to remove it by using a highly effective ink remover, sparing your screens the damage caused by unnecessarily using aggressive and caustic haze removers, thus extending the screens’ useful life. When deciding which haze remover will best meet your needs, you want to consider which type of haze is most prevalent in your shop. This reaction makes reclaiming difficult and often results in excessive ghosting. Additionally, a reaction may occur between partially hardened emulsion, which may remain on the squeegee side of the screen, and the ink. This leaves mesh threads on the squeegee side exposed and susceptible to staining from ink and emulsion. The only firmly anchored emulsion resides on the side closest to the light source-the substrate side. When developed, most of this emulsion rinses away along with the unexposed emulsion from the image area. Underexposure prevents the emulsion that encapsulates the mesh from the squeegee side from absorbing enough UV light to become anchored firmly to the screen. Here, the emulsion or film used to define the customer’s artwork most often causes the ghost haze however, the ghosting can be attributed to a combination of the emulsion and the ink staining the mesh in these areas. Inks also contain pigments that get trapped in between the knuckles of the mesh, bond to the mesh, or become partially dissolved by hot solvents and slightly penetrate the mesh.Īnother area we think about is the negative image created by the stenciled parts of the screen. These types of inks can create ghost haze that is difficult to remove. For example, catalyzed inks contain solvents that react with low-surface-energy substrates to improve ink adhesion. The severity of ghosting often depends on the type of ink used. The two basic types of ghost haze are stains left by the printing ink and those left by the emulsion. They remove ink and/or emulsion ghost-haze images (stains) that remain in the mesh after removing the ink and emulsion from the screen during the reclaiming process. Haze removers traditionally contain some form of caustic ingredient, such as sodium or potassium hydroxide and/or sodium hypochlorite, and may include a solvent or solvent blend, as in the case of most single-component haze removers. Ink removers are not intended to dehaze, but some show promise when used only for removing ink haze. They usually evaporate faster than ink washes and preferably leave little to no oily residue so tapes can be used promptly thereafter. These ink removers are used to open up a clogged screen, to clean excess ink from the substrate side of the screen, and for making color changes at press. Ink removers used while printing are classified as screen openers, press washes, or on-press cleaners. These ink removers evaporate slowly, contain emulsifiers, and are used during the reclaiming process. If used after printing, they are classified as ink washes or ink degradants. Ink removers consist of various blends of solvents used to dissolve inks for cleanup after printing, or for use while printing. These products are most frequently used to improve the durability of capillary and indirect films when longer production runs are required. The active ingredient is silicon carbide, which is a dark, insoluble, crystalline compound used to abrade the mesh. Degreasers are not intended to dehaze.Ībraders scratch the knuckles of the mesh at a microscopic level, which increases the surface area and helps improve stencil adhesion. Screens should be degreased just before the mesh is coated. ![]() They clean the mesh prior to application of emulsion or film and remove most forms of contamination and foreign matter from the screens so a smooth, uniform, blemish-free coating can be achieved. To simplify matters, let’s organize and define common screen-prep and cleaning products.ĭegreasers consist of one or more of the following ingredients: detergents, emulsifiers, surfactants, and wetting agents. There are abraders that dehaze and dehazers that abrade. Some degreasers also dehaze, and some dehazers also degrease. Join the Screen Printing Brain Squad - and Make Your Voice Heard!Īs the number of products referred to as haze removers continues to grow, so does the confusion over.Get Your Free Subscription to Screen Printing magazine. ![]()
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