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Giving up the Ghost: Tips for Preventing and Removing Haze

(July 2007) posted on Wed Jul 11, 2007

Ghost haze is a problem you can conquer when you arm yourself with the proper chemicals and employ sound techniques. This article examines products that help remove ghost images as well as methods you can use to reduce or prevent their occurrence.

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By Dave Dennings

As the number of products referred to as haze removers continues to grow, so does the confusion over what classifies as a haze remover. At times it seems as if there’s no clear delineation between degreasers, abraders, ink removers, and haze removers. Some degreasers also dehaze, and some dehazers also degrease. There are abraders that dehaze and dehazers that abrade. And now some ink removers allegedly degrease and dehaze. It’s enough to make your head spin. This article will try to clear up the confusion. Let’s first take a look at how this confusion started.

In an unrelenting quest for efficiency, screen printers look for ways to streamline their processes. Manufacturers of screen-cleaning products naturally want to oblige their customers, and thus began the process of developing performance-coupling, and in some cases tripling, products by blending components of a product designed for one purpose with components of a product designed for another.

If components separate in the container and the product is not thoroughly mixed prior to use, you will encounter inconsistencies in its effectiveness. If components react with one another, performance may be weakened or the pot life may be greatly reduced. Chemical manufacturers must take care when formulating multifunctional products to avoid combining ingredients that may offset or counteract one another. For example, stencil removers are acidic and most haze removers are caustic. Combining key ingredients from these two products to make a stencil/haze remover will likely not work because the active components may become neutralized by one another.

To simplify matters, let’s organize and define common screen prep and cleaning products.

Degreasers consist of one or more of the following ingredients: detergents, emulsifiers, surfactants, and wetting agents. 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. Screens should be degreased just before the mesh is coated. Degreasers are not intended to dehaze.

Abraders microscopically scratch the knuckles of the mesh, which increases the surface area and helps improve stencil adhesion. The active ingredient is silicon carbide, which is a dark, insoluble crystalline compound used to abrade the mesh. These products are most frequently used to improve the durability of capillary and indirect films when longer production runs are required. Abraders are not intended to dehaze.


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