Poor coating adhesion is a prevalent issue that can plague manufacturing and fabrication operations. When coatings don’t properly bond to substrates, it leads to defects, quality problems, and added costs. As an industrial coatings supplier with decades of experience, Sun Coating Company often assists customers in resolving coating adhesion problems. We’ve seen many of these issues first-hand and want to share some of the most common causes and remedies. With some adjustments to surface preparation, application techniques, and processing, you can get coatings to adhere correctly.
Surface Prep Sets the Stage
Inadequate surface preparation is one of the main culprits when coatings fail to adhere. This is particularly true when it comes to chemours Teflon finish. The substrate needs to be thoroughly cleaned and mechanically profiled to allow anchoring of the coating. Following the coating manufacturer’s guidelines for proper preparation methods is crucial. Here are some key factors to check:
- All contaminants, including oil, grease, rust, mill scale, and any foreign matter, must be eliminated from the surface through cleaning processes like solvent wiping or alkaline wash.
- The surface should be profiled by abrasive blasting, chemical etching or other methods. This profiles the surface and gives the coating something to grip onto. The proper height of this surface profile needs to be confirmed.
- Residual dust and particles after profiling should be completely removed by blowing off and vacuuming. Even tiny debris can get in the way of adhesion.
Curing Conditions Matter
Not properly curing the coating after application is another issue that can undermine adhesion. Each coating formulation requires a specific temperature and duration in the curing oven to fully crosslink and build bonding strength. It’s critical to closely follow the cure schedule listed in the technical data sheet. Some key points:
- Confirm oven thermocouples are calibrated for accurate temperature readings.
- Check that airflow in the oven provides uniform heat distribution without hot or cold spots.
- Meet the minimum cure time specified by the coating manufacturer. Shorter times risk under cured coatings with poorer adhesion.
Contamination Can Creep In
Small contaminants during the coating application process can also impair adhesion. Meticulous care should be taken to prevent contamination of the coating, substrate, equipment, and environment:
- Coating guns, hoses, and tanks must be thoroughly cleaned to avoid cross-contamination.
- Coatings should be filtered just prior to application to catch any particulates.
- A clean, temperature-controlled spray booth prevents issues from dirt, humidity, and debris.
- Bare hands touching coated parts leave oils and salts that inhibit adhesion.
Coating Selection Matters
Choosing coatings formulated for the substrate is critical for proper adhesion. Mismatching coatings and surfaces often struggle to bond. Be sure to select coatings designed for the specific material being coated, such as food processing coatings for metal pots and pans. Some tips include:
- For metal substrates, use coatings made for metallic bonding.
- Properly determine the plastic polymer type to match with the right coating.
- Consider a primer to anchor the topcoat when needed.
- Ask the coating vendor for guidance on the optimal coating options.
Test First
When possible, perform an adhesion test before a full production coating run to confirm the coating adheres correctly. There are several standard test methods that qualify adhesion strength.
Troubleshooting Tricks
If adhesion problems occur even after addressing the above factors, don’t hesitate to ask your coating supplier, like Sun Coating Company, for troubleshooting help. We can assist in diagnosing the root cause and finding a solution to get your parts coated with excellent adhesion.
When You Need Coatings Applied, Give Us a Call
With attention to proper surface prep, contamination prevention, cure parameters, and coating selection, many common coating adhesion failures can be prevented. But when challenges arise, work with an experienced coatings expert to get back on track. Following the right process will have your coatings bonding tightly for a beautiful, long-lasting finish. Reach out to our team anytime for adhesion troubleshooting or selecting the optimal coating for your application needs.