what to use for step test screen printing

Stencil Exposure Testing

Ulano 1-Step & Manual Grayscale 1. Tape positive to the screen. Yous don't need any special equipment to make an Exposure Step Test, just a coated screen, a typical positive with a variety of line thickness and some Ulano Rubylith™ masking film to block UV light. Yous are going to make 5 exposures by blocking portions of the positive as you betrayal it Ulano ane-Pace Exposure Estimator Exposure calculators simulate 5 exposuresat one time with a filter. The filters vary the amount of UV lite that gets to the stencil in ane exposure so you don't have to have the screen in and out of the vacuum frame every time you want to move the mask. The issue should be identical to the fourth dimension consuming manual step test. Older mode exposure calculators attached the filters directly to a camera picture show positive but this usually doesn't represent your actual conditions if you utilise laser or inkjet positives. Large calibrated filters like the Ulano One-Step can be placed straight over your laser or ink jet test positive for the best results. 1. Tape your positive to a typical coated screen. You should glaze all the screens in that mesh count the same so the exposure time tin be the aforementioned. You will non move this positive during this test.

2. Vacuum and expose to UV light. two. Place the coated screen with the positive taped on it into your vacuum frame and expose for half the fourth dimension y'all estimate as the estimated exposure time for this combination of light source and stencil. For case: I remember this screen volition have 4 minutes to betrayal, so my initial exposure will exist 2 minutes. Call up to use a rope to let air escape from inside the screen. 3. Turn off the vacuum and plow over the screen.

4. Tape Masking film over the positive. 5. Move the Masking Film and expose again. Ulano has excellent grooming videos for Direct Emulsion and Capillary Film, including sections on how to make an exposure test. 4. Tape a piece of masking picture show then information technology covers about one/fifth of the positive. Put it back in the vacuum frame and expose for 1 more minute. For the tertiary exposure, move the mask then it covers two/5ths of the positive and expose for 25% of the approximate exposure time. For the 4th exposure, move the mask so it covers 3/5ths of the positive and expose for 25% of the approximate exposure fourth dimension. For the concluding exposure, encompass four/5ths of the positive and expose for 25% of the judge exposure fourth dimension. The exposure times tin can be varied if you desire merely the goal is two exposures above and below the judge amount of UV light. Stencils with diazo sensitizer will take a color alter because the xanthous diazo will actually be used up and the stencil will render to the colour is was before y'all sensitized it. For the all-time durability, await at the department where y'all don't see whatever color change. This means the stencil reached information technology's saturation point, and more lite just doesn't change it whatsoever more than. Don't waste matter time exposing it if it won't change any more. Process the stencil in the usual manner and look for signs of under exposure on the squeegee side of the stencil, where the stencil volition wash away because information technology didn't go enough light to alter it so it won't deliquesce with water. When the stencil is dry, brand a print with it. Compare it to your positive and expect for the best resolution. Decide if there is a difference between the section where the color stops changing and the all-time resolution. Here is where your judgment is required. If they are both in the same section, you now have proof of the best exposure. If not, you lot volition need to sacrifice durability or fine lines or change emulsion. Write the exposure for this emulsion and mesh count in a rubber place and call up that unlike mesh counts will take different stencil thickness and unlike exposure times.

Shut-up of filters over your positive Transmission Grey Scale In one case y'all know your optimum exposure, apply a small transmission gray scale on every screen you lot expose, so you will know if your conditions have inverse. A manual greyness scale is a pocket-size film positive with darker and darker filters adjacent to each other. When you have one on the stencil every bit you expose you will become a simulation of many different exposures to the stencil. When you wash out the stencil, areas that didn't get enough exposure will deliquesce with water and go down the drain. Using the exposure you determined was best with your larger exposure test - you can make up one's mind how many steps of the gray scale will resist washout and stay in the screen. Ordinarily there will be a step that washes away a piddling between an open area that dissolved and the kickoff step that survived. Count the steps and document that this stencil and mesh count should get a solid step 4 (this is only an example, your results will vary). When y'all put a greyness scale on every screen, you will find when it washes out differently and y'all volition know your lamp or stencil is different and you have to change your exposure.

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Source: https://www.lawsonsp.com/technical-support/support-articles/249-emulsion-film-stencils/384-stencil-exposure-testing

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