![]() When the screen is dry apply the last coat of emulsion on the face side covering only one third of the same direction as the last face coat, then dry. When dry, face coat with the sharp edge of the squeegee two thirds of the screen from a crossing direction (perpendicular) then dry face up. Coat again the squeegee side on only two thirds of the screen, then coat again one third of the squeegee side (all wet on wet).ĭry your screen as normal. Then coat the squeegee side once over the entire screen. ![]() The step coating procedure starts with a stroke on the face of the mesh. 2) is used to coat a screen to find your best coating technique for that mesh count. Your emulsion manufacturer can recommend a coating procedure for each mesh count using a rounded or sharp coating edge. Emulsion drip from the mesh while drying is a definite indication that the coated emulsion is too thick. Too much emulsion on the face of the screen can cause difficult ink transfer and details can break down in a run. With an emulsion stencil, more is not better. Manufacturers recommend an EOM ratio of 10 to 20 percent. 1) Too low of an EOM ratio will prevent a good gasket seal, prevent good detail resolution, and increase chances of saw tooth edges. ![]() EOM is a percentage of the mesh thickness. In addition, lower solids percentage will require multiple coatings to achieve reasonable mesh coverage.Įmulsion Over Mesh or EOM is a measurement of the emulsion thickness on the face or substrate side of the mesh. Solids content less than 30% with low viscosity are often difficult to coat without a mess. Lower temperatures cause the emulsions to thicken. Emulsion viscosity can also change with temperature. The solids content in an emulsion does not always reflect in the viscosity An example would be that pure photopolymer emulsions are available in very high solids content with low viscosity. Pure photopolymer emulsions have the highest solids content available with reasonable and often excellent viscosity. Pure photopolymer emulsions have good resolution, definition, and bridging qualities. Pure photopolymer emulsions are the most expensive and are best matched with high quality single point exposure systems. They are pre mixed and have the longest shelf life. SBQ- Photopolymer emulsions are very fast in their exposure speeds but also have the smallest exposure latitude. Dual cure emulsions are midrange in price, and higher solids content versions are available with reasonable viscosity. Dual cure emulsions generally have the best resolution, definition, and bridging qualities. Dual cure emulsions will have the largest exposure latitude and are available in various levels of water and solvent resistant features. Due to the hybrid nature they have the largest available feature and quality range. Dual cure emulsions are the newest available emulsions. Drawbacks are that many require hardeners for long runs or water resistance lower solids content is often needed for reasonable viscosity.ĭiazo Photopolymer emulsions are hybrids of the diazo and photopolymers and are also called dual cure. Diazo emulsions are mid range in available exposure latitude and can have good edge definition. There are also three photo reactive film choices, indirect film, direct/indirect film, and photoreactive capillary films.ĭiazo emulsions are the least expensive and the first of the three emulsion types available on the market. There are three direct emulsion choices, diazo, diazo/photopolymer (dual cure), and SBQ-photopolymer. Screen printers have available six types of photoreactive stencil materials.
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