Haze Remover for Screen Printing
Defining ghost images
Have you ever wondered what a ghost image is? A ghost image or haze is a stain left on the screen after cleaning. Ghost images occur from staining on the screen from either ink or emulsion. Ink stains occur from certain hard-to-clean inks such as catalyzed or silicone inks. Improper cleaning techniques can also result in ink pigment trapped in the knuckles of the screen mesh. A haze remover for screen printing can help you avoid ghost images.
Ghosting from emulsions is attributed to the negative image created by the stenciled parts of the screen. Improper exposure of screen printing emulsion or partially hardened emulsion on the squeegee side may also cause the mesh to be susceptible to staining from the ink.
Deciding on a stain or haze remover for screen printing
Once you understand what type of ghost images you have in your screens, it is easier to decide how to tackle them. If you encounter plastisol ink stains in your screens, then a high-quality solvent screen wash/stain remover will have the best results. These products are effective but are gentler on the screen mesh and thus extending the life of the screen.
For ghost images caused by graphic ink and/or emulsion use a haze remover for screen printing. First, use a caustic haze remover like HR-350. Follow this with the application of a solvent screen wash/activator like Bio-1. First, apply the caustic haze remover and let it dry on the screen for a set period of time. Then activate (re-wet) with the solvent screen wash. Follow the solvent screen wash with a high-pressure rinse. When using caustic haze removers be sure to follow the manufacturer’s stated directions and safety precautions.
Factors that cause ghost images
Use of hot solvents. Hot solvents do not get their name from a high temperature degree. They are solvents that flash off or evaporate very quickly. These are flammable solvents used in can screen openers or low flash point press cleaners like MEK or acetone. The use of these items causes screen mesh to swell and allows ink pigment to become trapped in the weave of the mesh. Removing this trapped pigment can be a difficult task. But using a super strong caustic haze remover like GIR-4U Plus will do the trick. Save yourself the headache and don’t use hot solvents in the first place to avoid this issue completely.
Leaving ink in screens for too long. Delaying the removal of ink from your screens can be problematic. The longer you leave ink in the screen, the worse your staining issues will be. Some inks are more forgiving than others. Screen printing graphic inks are notoriously the worst for staining. Reclaiming these screens should never be delayed.
Pro Tip: If delayed screen reclaiming is unavoidable, card out the ink and spray the screen with a slow evaporating screen wash such as ProWash. This will help reduce the ghost image staining when immediate screen reclaiming is not possible.
Avoiding ghost images during reclaiming
Incorrect screen reclaiming procedures. Sometimes ghost images are self-induced. Avoid taking shortcuts in the reclaim process or using poor procedures. During screen reclaim, be sure to always apply ink degradant to both sides of the screen, scrub both sides, and high pressure rinse both sides. Proper reclaim procedures will help avoid leaving ink or emulsion behind that would appear as haze.
Fake ghost images or haze. This can happen when your screen appears to have a shadow from a previous job or design, especially when viewing the screen at an angle. The most common cause of this is from flattening or elongation of the screen mesh. This can happen from long runs or high squeegee pressure on the mesh. Using a screen printing abrader/degreaser such as Pink Scrub will rejuvenate your screen mesh. Screen abraders with degreasers will also condition the mesh. This will improve your stencil bonding and durability.
Ghost images can be caused by a variety of situations. But using a haze cleaner for screen printing will resolve many of your ghost image issues.