Alex Mammoser looks at the best ways to clean and maintain screens
I have made a living helping people in their screen rooms. It is all too often I walk into a shop and the most neglected area is where they process the screens. People so easily forget that we are screen printers and once the art is done we have the most important job in the shop: make a quality screen.
The first step is finding a good clean screen to burn your stencil with, either on your CTS unit or with film. But for this process to start with a clean screen, it needs to finish clean.
Cleaning screens is never anyone's favorite job and is often given to the newest employee as a rite of passage. But having your screen tech properly trained on how to clean a screen and what to look for/do when one is wrongly processed is a skilled job. Many times, the issues we see has to do with the mesh still being dirty when it leaves the reclaim area. In order to prevent this from happening there are many variables, but if we reduce these to a crucial few we can eliminate 90% of the issues.
Keep your reclaim wash out and stencil development in separate booths. Having two wash out booths is beneficial to keeping chemistry away from clean mesh/stencils. A wash out booth that is dirty and has chemistry on the walls will have a tendency to splash back onto the screens causing pre-mature breakdown and unwanted hardening of the screen. This is because the same chemistry that is used to reclaim screens can also harden them if left to dry on the emulsion. If you hear your chemical rep talking about a flood rinse at the end of the reclaim process, this has two purposes. The first is to check the mesh for any imperfections left; if the water is not sheeting down the mesh like waves on a lake there is likely something left in the knuckles or on the surface that needs to be removed before drying. The second reason to flood rinse is to wash off any of the chemistry that has blown around the wash out booth and landed on the screen after you're finished with the dehaze/degrease process. The flood rinse will allow any remaining chemistry to slowly wash off the screen and reduce contamination.
I often hear from reclaim operators that high pressure will break or wreck mesh. While this may have been true years ago today's mesh technology has come a long way and is able to stand up to higher pressure. Investing in a $200 [£150] pressure washer is okay for washing your stencils or just getting started, but if you really want to clean the knuckles of the mesh properly and quickly, you need high pressure.
Pin holes or poor development come from left over debris in the mesh. Not being able to completely clean the knuckles will also lead to poor ink flow and cause reclaim operator to use too much pressure or the press operator to double stroke on press. Investing in a $1500-2000 [£1120-1490] pressure washer may seem daunting at first, but the benefits far outweigh the initial cost. The pumps are almost always rebuildable and are built to last,and increase the speed at which you can clean your screens dramatically, with higher pressure you will find that time be on your side at the end of the day.
Chemistry not originally intended for use in this industry or poorly designed chemistry is the root of many issues. While turpentine, mineral spirits and other hardware store cleaners will remove ink, it usually comes at a much higher cost than anticipated. Employees will soak rags with the chemistry, wipe up as much as they can and then toss the remainder in the bin. Not only is this a waste of chemistry and of course money, these products may leave an oily residue and may make reclaiming very difficult.
Almost all local ink suppliers will have something available that will work better than the hardware store products. But we can do better than that. Look for chemistry that is re-usable; companies will make re-circulation systems that house chemistry, that will sediment out ink and separate it into two layers in little time. You can reuse the clean chemical, and have less waste going into the bin. For the reclaim process consider dip tanks. A dip tank is a great way to save money on both ink degradant and emulsion remover. By combining this process, you will eliminate the need to use an ink degradant first (saving on cost) and shortening the time to process screens. After reclaim you will usually be left with a stain/haze. Trying to find chemistry that is non-caustic and non-abrasive to remove your stains/haze is difficult. The easiest products to locate, i.e. caustics, are not great for the health, but work well to remove stains, leaving these caustics on screen or continued use can reduce mesh life, abrasives types of products are not great for your mesh life either but will remove stains, the issue with abrasives are that they create microscopic nicks that allow pigments to lodge in them, this creates a never ending cycle of staining and re-abrading to remove the stain.
There is chemistry available though that can remove stains and haze and degrease your screens all at once, Staining is drastically reduced over the life of the mesh when neither caustic or abrasion of the mesh occur. A combination of chemicals reducing cost by eliminating processes and shortening your time to finish and increasing mesh life and cleanliness will make any owner happy.
Alex Mammoser - International Sales Director // Easiway Systems
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