![]() It works but it is a very inferior emulsion compared to the brand types that are now available. I made my own emulsion with gelatine and potassium dichromate. I used to buy this from chemists (pharmacies) back in the days when raw chemicals were sold over the counter. The "orangy powder" you refer to is Potassium Dichromate. Make sure you wear rubber gloves, eye protection and old clothes!! Caustic soda is also an effective degreaser in weaker solutions. Using a nylon bristle brush, paint a solution of caustic soda on both sides of the mesh and leave for 20 minutes or so. This is only safe to use on synthetic fabrics as it will dissolve cotton organdies. But be VERY careful and, ideally, do it outside (don't wash screens in the bath as the caustic soda will roughen the bath surface). If you want an effective non-brand cleaner, you'll need something like caustic soda, which was what I always used. When you go home I want you to use a key to open your front door, not the kick of brute force.Ĭlick to expand.I did my share of screenprinting on a shoe-string a few years back and I am familiar with using bleach as a reclaimer. Many will answer, "but it works", this is a classic do you have time or money question. ![]() It takes more bleach to do the work of a small amount of SMP. No cross-links - hard to reclaim.Ī stencil may have worked OK with harmless plastisol, but if you clean the ink with a strong solvent, the solvent can attack the defenseless under-exposed stencil and chemically bond it to the mesh that only a razor blade can fix.īleach is used to remove gelatin indirect stencils, but bleach is inferior to SMP for breaking UV cross-linked diazo or SBQ. This this hard to reclaim effect also happens with under-exposed stencils. If you use 3,000 psi water, you don't even need a chemical to breakdown your stencil, but it helps to have tight mesh to resist the pulsing water from a pressure washer. Yes you will also lose mesh tension blasting the mesh as it vibrates like a drum, if the stencil doesn't come out. There is no chemical to break down this chemical combination except the brute force of water pressure. If you let this "soup' of stencil remover & emulsion dry on the mesh before you can rinse them down the drain, they form a new chemical bond that is permanent. Industrial stencil removers use Sodium MetaPeriodate (SMP, CAS ), to attack these cross-links, releasing breaking down the stencil so it will dissolve, and you can reclaim the mesh and coat it again. ![]() Linked together, and woven in and out of your mesh, the exposed/cured/hardened stencil will not dissolve with water and rinse own the drain. UV energy reacts with diazo or photopolymer sensitizer in the stencil and causes a chemical cross-link between the two components that make up the "emulsion". If the exposure time is too short, or UV energy doesn't move all the way through the stencil, the cross-linking is incomplete, and complete resistance isn't achieved. Shelf life for the sensitized emulsion is 4 weeks at 32 Celcius, 8 weeks at 21 Celcius and 4 months when refrigerated.Water or solvent resistance of a stencil depends on the complete cross-linking of the ingredients by the sensitizer with UV energy. Step 3 – Properly mixed Diazo Photo EmulsionĪlways store the sensitized emulsion in a cool and dark place. The colour will change from sky blue to a grassy green when the Photo Emulsion has been correctly mixed. Thoroughly mix the prepared Sensitizer solution with the Photo Emulsion by stirring, not shaking. The Diazo Photo Emulsion should appear a bright blue before adding the Diazo Sensitizer. Step 2 – Pour prepared Sensitizer into Photo Emulsion You should see a colour change in the sensitizer after mixing with water. ![]() Fill the sensitizer bottle approximately ½ full with water (tap or distilled water works just fine.). It is critical to add water to the sensitizer and completely dissolve the paste into water. This bottle does not come with a seal. The Diazo Photo Emulsion Sensitizer bottle contains a very small amount of a thick paste that can sometimes settle on the side of the bottle. Step 1 – Preparing the Diazo Photo Emulsion Sensitizer
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