If a metal substrate isn’t completely clean when you apply paint, fisheyes can rear their ugly and costly heads.
Unfortunately, most people who have ever been involved in metal coating know how disastrous fisheyes can be. These imperfections appear as craters on the paint surface. If no one catches fisheyes in time, you can easily run an entire shift with serious consequences.
If you’re in the automotive industry, for example, you would likely have to pay labor and material costs to strip the paint before getting into more painful costs. Some car manufacturers use a high-performing liquid or powder paint that contains metal flake. This type of coating can be several hundred dollars a pound, so the price adds up exponentially if you have to double how much you’re using.
In addition to the drain on your budget, production interruptions upset your customers because they are not getting shipments on time or are receiving defective products that slipped past your quality control people.
At the first sign of fisheyes, shut down the line until the issue is identified and addressed.
Fisheyes all relate to some unwanted contamination such as oil or silicone that is present on the metal, and these culprits can come from almost anywhere, from the metal when it arrives on your line to dirty shop rags. Silicone is especially difficult to remove.
If you’re spray-painting a piece of metal, contaminated air around the area can cause fisheyes. If you have a contaminant inside your sprayer, that can lead to fisheyes. If someone is using a maintenance aerosol near a coating-application area, the silicone or petroleum in the spray can be atomized in the air and travel into the coating area leading to — you guessed it — fisheyes.
When I am helping clients troubleshoot for fisheyes or craters, I always ask if a new material was recently introduced or if their process recently changed. If that doesn’t bring to light the source of the problem, we consider the metal provider. Some metal manufacturers and distributors can be protective of their processes. So, if the steel suppliers aren’t willing to work with you to fix the issue, consider finding a new supplier.
Once the contaminant is found, we can try to use a solvent such as acetone to clean up the issue. With enough effort, you can control everything to a degree. Paying close attention to the cleanliness of paint lines, sprayer air lines, air quality, cleaner baths, shop rags and the environment in which you’re working is critical to fisheye prevention.
Here are five tips for preventing fisheyes from occurring:
- Know where your metals are coming from. Know who the source is and be able to trust that source. You need to have a good contact person who can answer your questions quickly. Before you bring a new metal into your facility, be sure your supplier understands which contaminants can shut you down so they react accordingly.
- Set up a process to properly and adequately clean all soils off of the metal.
- Eliminate any source of contaminants that contain oils, silicone or other contaminants that cannot be cleaned with your current process.
- If you use shop rags, use high-quality shop rags and don’t reuse them. (NOTE: Accessa Coatings Solutions sells high-quality shop rags. Contact us to learn more.)
- Be sure your paint air supply lines are being filtered for moisture and oil. At the beginning of every run, your filters should be checked to be sure they are performing optimally.
Fortunately, cleaners capable of handling the contaminants are available. I often help customers identify contaminants, recommend solutions and offer recommendations on how they can avoid these issues the future.
If your coating line could be cleaned up to help prevent issues such as fisheyes, contact HIT Solutions at 877-771-4HIT.