Chapter 18
Reclaiming, Stripping And Reusing Screens
This part of the process is done when we need to reuse the screen for another job. The chemical needed is called "reclaimer" or stencil remover. It most likely will need to be diluted but there are some that you buy ready to use. It is most often put in a chemical resistant spray bottle and kept with other chemicals in your washout booth. You will need a place with running cold water and a drain that chemicals may go down. Whether you have a septic system and a leach field or are on a city water treatment sewer system, you will want to consider filtering the waste water as much as possible. There are chemicals that are “CA drain safe” meaning they are known substances the CA water treatment systems are known to be able to remove effectively. Filtration will help reduce and/or eliminate water soluble chemicals and solid particulates. Filtration systems that use screens or “coffee filter” type media do not remove water soluble chemicals. They will remove solid particulates only. To remove or reduce soluble chemicals, you will need a carbon activated canister type filter.
VIDEO: Tips For Cleaning Ink Off Screens
VIDEO: Washout Booth Environmental Filtration Unit
After you have finished printing a job, clean the screen of any ink and all tape. Put it in the washout booth and spray both sides of the screen with the stencil remover. You should see the emulsion start to dissolve when you apply it and agitate with a brush or scrubby pad. Use the brush to massage the stencil remover into the emulsion. Once it looks like it is dissolving, begin to rinse with a pressure washer.
Note: A pressure washer will be necessary for most screen reclaiming. Some screens will be very difficult and the pressure washer will be a must. Others may be very easy and will not need much pressure. While others are easy enough to reclaim with the pressure washer and no emulsion remover. The bottom line is that different screens will pose different levels of levels of labor needed to do the job. A pressure washer is used here to reduce physical human labor, water, and time in most cases. You will want both a pressure washer and a garden hose with a spray nozzle. Both will feed off the cold tap water. Obviously, the garden hose setup is used to washout the stencil as described earlier.
The emulsion should begin to dissolve and wash away with the spray from the pressure washer.
VIDEO: Reusing Screens
Be sure to reclaim screens from the inkwell side of the screen. With the screen coating and drying method described here, most of the emulsion will be on the substrate side of the mesh. Therefore, it is easier to push the emulsion off the mesh rather than through it. Be thorough and remove all debris from the mesh and frame. The screen and mesh should be as clean as possible. Stains and/or emulsion stuck in the corners where the mesh meets the frame are irrelevant.
Emulsion coming off the mesh can and will stain anything it comes in contact with if left for long periods of time. The washout booth will get stained with emulsion and emulsion bits. Clothing can also be damaged and you will want to take off any jewelry that may interact with chemicals.
VIDEO: Washing Out The Stencil & Reclaiming
VIDEO: Tips On Reclaiming Screens
VIDEO: Time Lapse. 1 Hour Of Reclaiming In 5 Minutes
Again, be meticulous. Give the screen a thorough cleaning making sure all residual emulsion is removed. I like to make sure the entire screen is very clean at this point. Check for any ink that may have been missed and stray emulsion bits and pieces on the frame itself. Rinse well.
VIDEO: Can You Reclaim Screens Without A Pressure Washer?
VIDEO: Why Won’t My Emulsion Stencil Reclaim?
VIDEO: How Many Times Can Screen Mesh Be Re-Used?
Removing Stains And Unwanted Haze Or Ghost Images
Sometimes the ink you have printed through the screen will stain the mesh. Ink colors like red, navy, black, maroon will visibly show a stain on the mesh. Lighter colored inks may not show visible stains but they can adhere to the mesh like any other darker color. When the stains become bad, you will want to remove them for various reasons. Hazing can cause ink flow problems and even emulsion adhesion complications. What is happening here is the ink is building up around the mesh threads. This in turn results in smaller mesh openings. Smaller mesh openings mean impeded ink flow. You can see a negative of the previous stencil in lager print areas of the current stencil. For emulsion it means the emulsion is trying to adhere to the ink covered mesh threads.
The chemical needed to remove ink built up on mesh threads is called haze remover or de-hazer. It may also be referred to as stain remover. This comes in different types of products. Some are spray-able and others are a paste or gel like and need to be swabbed onto the screen with a brush. Most will need to sit for a few minutes before rinsing out with the pressure washer. Others can be aggressive and will tear the mesh if left on the mesh for too long.
After removing the stencil and rinsing well, apply some of your haze remover in the manner described by the vendor. Follow the specific instructions for your haze remover and rinse well with your pressure washer. Usually this means applying the stain remover to the affected areas and let stand for 2 to 5 minutes. Then follow up with a careful pressure washing of the entire mesh area. Allow the screen to dry.
Haze removers are probably the most hazardous chemicals to work with in screen printing today. They can itch or burn if the stain remover makes contact with your skin. Remember that when you use a pressure washer the chemicals will become airborne in the water vapor coming out of the washout booth. Do not breath in any of the water vapors coming out of the washout booth when using chemicals of any kind.
VIDEO: Reclaiming & De-Hazing Screens Expanded
VIDEO: Tips On Reclaiming Screens