Monitoring Aqueous Coatings for Smooth Operation

Kiss Impression

Set up the coater to the manufacturer’s recommendations. Set to run at minimum pressure to a “kiss impression”. Complete make-ready before engaging the coater. Water spray any blanket, plate or roller surfaces that are not rotating or being rewet with coating whenever the press is stopped. Fast drying aqueous coating will dry on these surfaces just as it dries on a coated sheet. Before re-starting, wash down these surfaces so that they are tack free.

Monitoring Coating Drums

Monitor a drum in use and replace it with a fresh drum when it is about 3/4 empty. The remaining coating will typically be thicker because of volatiles evaporation during circulation over the coater cylinders. The coating remaining in the near depleted drum may be added to the fresh drum as it empties providing room. Best practice recommends always covering an opened drum to prevent evaporation of coating volatiles. Further, when storing, place a sheet of polyethylene film into the drum in direct contact with the coating before lid closure to prevent loss of volatiles into the drum’s headspace.

Diaphragm Pumps

Diaphragm pumps are recommended to circulate coating from the supply container to the coater and back. Suction and return lines can be connected to fittings on a drum lid, which connect to PVC pipes plumbed to reach the drum bottom. The suction feed pipe should be capped with a wire mesh ball filter. Pump to satisfy coater demand only, and not excessively creating foam. Cut the bottom of the return line pipe reaching into the drum to a 45° angle. Also, cut the length of this pipe with spaced vertical 4” long x 1⁄4” wide slots to allow coating to flow into the drum without splashing and creating foam.

Aqueous Coatings Safety

Handle aqueous coatings with care to avoid skin and eye contact by wearing protective clothing, gloves, and glasses. Don’t inhale evaporated vapors for an extended time or ingest. Any coating spills are very slippery and need to be mopped up quickly, or absorbed with an inert material. Dried coating films are tough, but they can be removed from surfaces using a 10% ammonia/water mixture, or an oven cleaner.

After a run, thoroughly wash the application blanket, impression cylinder, rollers, anilox, and associated equipment with water. Drain any coating pan or reservoirs pumping coating back into the supply or other drum. Finish with a clean-up mode, flushing, and rinsing all application equipment and hoses, running at least 5 gallon of water through the entire system.  Dispose of empty containers and diluted wash water in accordance with local regulations.

Corks’ business is the development and formulation of Aqueous, energy curing Ultraviolet (UV), and Electron Beam (EB) specialty coatings and adhesives. Cork thrives on its ability to formulate novel, useful specialty products that offer the graphic arts industry printer/coater a competitive advantage.  Contact us for your next project, and get expert help from the start.

Source: Cork Industries