Back by popular demand, the noted trainer and consultant Charlie Taublieb shares his secrets for HD success.
You can make stencils for HD printing with certain types of direct emulsions or with thick capillary films. I’ve worked with both, and my opinion is that capillary films definitely make more sense for this application. The issues I have with direct emulsions are the time it takes to apply them, the number of coats it takes to get the needed thickness, and the difficulty of duplicating the results across multiple screens, which takes a high-quality coating machine to do predictably. Capillary films are easier to apply and you can get them in thicknesses ranging from 100 to 1000 microns. The most popular films for HD printing fall between 200 and 400 microns. Thicker films might require you to use wire meshes with 80-micron threads and will require very long exposure times. It’s also very difficult to get good, clean prints from such thick ink deposits.
Applying the capillary film to the mesh is where many printers run into problems. Because the films are fairly expensive, I cut them down to size when I can, leaving a 1-inch border on all sides of the image area. I find it’s easiest to use a “build up” board that is slightly bigger than the film but smaller than the inside dimension of the frame, and then laying some newsprint on the board before placing the capillary film on it (emulsion side up). Then when I have the screen in the exact position I want it, I lower it (print side down) onto the emulsion.
Many printers use water to apply the mesh as they do when making screens for their regular work, but it’s not the right choice for HD printing. For one, the water will reduce the thickness of the stencil and therefore the ink deposit. Also, because the capillary films used for HD printing are so thick, water doesn’t always adhere them to the mesh very well and they can delaminate from it during the printing process. For this application, use direct emulsion instead of water to apply the capillary film. I prefer using SBQ-sensitized pure-photopolymer films and emulsions for HD screens because they are the fastest to expose.
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