Q: I am a dentist in Florida and am experiencing problems with the finish to my dental equipment. The equipment is three years old, and the epoxy/polyester powder coat is bubbling up and chipping off the delivery units (the movable tray holder that the instruments sit on).
The paint is covered with a protective plastic that is lightly adhesive and disposed of after each patient. The paint is wiped down with a hospital-grade disinfectant wipe after every patient as well. We first started noticing the bubbling and “corrosion” about 18 months of use.
I have never seen this before in the 25 years that I have been working in dental offices. I have had dental equipment that was over 40 years old, disinfectant with diluted bleach that never displayed this type of wear.
The manufacturer said they never experienced this phenomenon on any of their products. They insist the units were manufactured in the U.S. according to FDA standards.
Can you think of any reason why this would happen?
A: From what you describe, there can be a couple problems that are responsible for the coating failure. Here are some of the possibilities:
1. Incorrect or poor-quality powder coating
The applicator may have pulled the wrong product off the shelf (e.g., mistook one white powder for another) and applied it to the dental equipment. A standard polyester product would not have the chemical or solvent resistance that a hybrid would.
A more remote possibility would be a lousy quality batch of powder coating as supplied by the powder manufacturer. This doesn’t happen very often, however.
2. Inadequately cured powder coating
The applicator may have applied the proper coating but didn’t bake it at high enough temperature or time to adequately harden or cure the coating. An under-cured powder coating will have poor chemical resistance and could blister and lose adhesion.
3. Poorly cleaned and pretreated metal prior to powder application
This is highly probable. If the instrument parts weren’t thoroughly cleaned and pretreated prior to applying powder coating, this could result in premature bubbling and adhesion failure.
Adequate cleaning and pretreatment would consist of a minimum of five stages, including an alkaline cleaner, intermediate rinses, and the application of a phosphate solution. Without this, the coating will not anchor to the metal substrate and will subsequently corrode and lose adhesion.
As for the FDA standards, these regulate the composition of the powder coating. Details are contained in the Code of Federal Register (CFR) 175.300. The purpose is to ensure nothing leaches out of the coating that could harm a human. It does not regulate the performance or durability of the coating.
Did the equipment manufacturer provide a warranty for the performance of the equipment? I would think they are responsible for the durability of the equipment, including its finish. They should correct the problem or replace the equipment. It would then be up to them to pursue the powder coating applicator (if it is not them).