Nonstick Coating Basics
Getting a great nonstick surface on a particular product isn't as easy as simply spraying it with a coat of polytetrafluoroethylene (PTFE). Though some have called it a miracle material, PTFE coatings (also known as Teflon®) can't work wonders on their own. It requires proper preparation, deliberate application, and careful curing for it to function as intended. Blistering, peeling, or flaking can result from missteps in any or all of three specific areas, including:
- The preparation of the surface onto which the coating is applied
- The thickness of the Teflon®/PTFE coating
- The curing process
Surface Pretreatment for Nonstick Coatings
No matter the type of product being coated, its substrate needs an initial cleaning or treatment to prepare it for the nonstick coating. The nonstick coating applicator may start by roughing the surface by either:
- Blasting it with aluminum oxide
- Etching it with chemicals, or
- Applying a phosphate coating
The practice of blasting, etching, or phosphating the substrate helps the PTFE bond to it and provides for a longer-lasting and more durable final product.
Nonstick Coating Thickness
The way in which a licensed coating applicator applies a Teflon®/PTFE coating to a substrate is also an important factor in the nonstick coating process. Best practices dictate putting on the coating according to a specific dry film thickness (DFT), normally 0.0003-0.0008" per side for a 1 coat system. Yet, an overly generous amount of DFT might result in a flaking or blistered finish, while applying too little may leave the final product with an incomplete layer of Teflon®/PTFE.
The Curing Process for Nonstick Coatings
Though curing comes last in the coating application process, it can cause a disproportionate number of problems if performed incorrectly. PTFE-coated products need to be heated to a temperature between 715° and 750° F to correctly cure. Exactly how long the curing process takes, however, will depend on the nature, size, thickness and material of the coated products. Under curing of the Teflon®/PTFE will result in the coating not being sintered and premature failure.
There are as many potential blemishes that can result from variables in the curing process. Too low of a temperature can cause coatings to peel while heating too quickly can lead to a pebbled appearance. Other issues might include a dull finish and/or a visible fissuring of the nonstick coating.
When the correct steps are followed to apply a nonstick coating you can ensure a more functional final coating with the required properties of Teflon®/PTFE.