Reclaiming SWR Emulsion
When it comes to removing SWR emulsion there are a few things to consider. First you need to look at the emulsion itself. SWR emulsion is a water resistant emulsion made for screen printing water based and discharge inks. Typically standard emulsion will start to break down with water, so if you used standard emulsion when screen printing water based inks than your screen would start to break down. SWR emulsion was developed to resist breakdown while printing water based inks. Due to its water resistant properties it is much stronger and more resilient than your standard emulsion. This means that since its stronger and holds up better under water based printing, it will be stronger and resist reclamation from emulsion remover and water.
So if youre having trouble reclaiming an SWR or water resistant emulsion screen, keep in mind, youre not the first. Even large shops and very experienced printers have to take a different approach to reclaiming this type of stencil. These helpful tips will help you be more successful reclaiming SWR Emulsion or water resistant emulsion in the future.
Lets start at the beginning, screen exposure. When it comes to exposing, printing, and reclaiming ANY screen, its imperative your exposure is proper to begin with. Before the screen is exposed, the emulsion is soft, as the screen exposes the emulsion hardens and becomes resistant to water, ink, and chemical. However, if the screen is not properly exposed it allows these fluids to receipt into the emulsion which can cause chemical reactions within the emulsion. This can make the screen extremely hard to reclaim. Its very important that you properly harden a stencil during the initial exposure to insure that the screen is resistant to this fluid interaction. If you are getting slime on the back of your screen during washout, this means your screen is under exposed. You should increase your exposure times until this slime diminishes. Of course if you are increasing your exposure times, its imperative you have extremely dark transparencies, with a dark transparency increasing exposure times doesn't contribute to trouble washing out the design because the positive image is still unexposed. For help dialing in exposure times, its always a good investment to get a simple screen exposure calculator.
After a proper exposure to harden your stencil its also good to take extra measures and post harden your screen. Post hardening your screen can insure stencil resistance and harden the emulsion an additional 10-15%. Post hardening will NOT compensate for improper exposure, however it will help prevent premature breakdown and insure easier reclamation. To post harden your screen, simply put your screen outside in the sun to dry, sunlight has is a great source for UV and will do a fine job at post hardening your screen. You can also expose the screen for the second time after the stencil is washed out and the screen is dry. If you have a lot of fine detail in your job, let your screens dry first before post hardening to insure the stencil will not shrink as the screen dries.
Lets move forward to cleaning. A simple thing to remember when cleaning ink out of the screen is to avoid the use of harsh solvents. Use environmentally friendly chemicals to clean the screen, this will interact easier with the emulsion and prevent the risk of chemical lock.
When it comes to removing the emulsion you want to use a more concentrated emulsion remover when reclaiming SWR since SWR is a stronger emulsion. If youre used to diluting your emulsion remover, we would recommend going strait out of the bottle when reclaiming SWR. Insure the screen is clean and the ink is properly remover, spray on the emulsion remover and allow to soak into the screen for several minutes as you use a screen scrub brush to degrade the emulsion. Never, and let me stress NEVER, let the emulsion remover dry on the screen. This will permanently lock the screen and make it virtually impossible to reclaim. After you how worked the emulsion remover into the stencil its time to wash out.
Since SWR and all other water resistant emulsions are stronger, pressure is a MUST during the reclaiming process. Sorry folks, the garden hose is not going to cut it this time! Use a 1200-1500 PSI pressure washer to help blow out the stencil. Screen mesh is surprisingly resilient and hold up to a lot of pressure! If you dont have access to a pressure washer, you can take your screen down to the local DIY car wash, put a few quarters in the machine, and use that pressure washer to reclaim your screen. Having a pressure washer by your washout sink will keep your screens cleaner, help them last longer, and make your life much easier. If you dont have one, go pick one up at the local hardware store, I've seen them as low as $59.
Other things to try. To reclaim harder stencils, the use of a dip tank can help the emulsion remover work into the stencil and ease the reclaiming process. Dip tanks use an emulsion degradent that is not as strong as emulsion remover but very effective when soaking the submerged screen for 4-5 minutes.
Another way to get out stencils that just wont come out with standard emulsion remover is dehazer. Dehazer like Liquid Renu It can help break down stuck emulsion and will also degrease your screen at the same time. There is more powerful dehazers on the market that come in a paste form that will work even better, these however are often fairly caustic and hazardous and should only be used in extreme circumstances.
The last thing to keep in mind when it comes to using harder stencils like SWR water resistant emulsion or even DCM solvent resistant emulsion is that since these stencils are harder to last during printing, they youll need to work a little harder reclaiming them, and they are a little harder on the screen mesh. A screen used primarily with a resistant emulsion will last about 20% less than a screen used with standard plastisol emulsions. Fortunately, the benefits outweigh the work every time and the prints printed through water resistant emulsions are beyond what a standard plastisol ink or emulsion could never produce.
Screen exposure problems can be one of the most frustrating issues in the screen printing process. These videos cover most of the common issues with screen exposure. If you are having problems exposing your screen or with your image washing out, we highly recommend watching these videos that help trouble shoot screen exposure problems.