With multiple topcoats, ETFE builds can reach 50 mils DFT.
ETFE (ethylene tetrafluoroethylene) is a thermoplastic copolymer derived from the polymerization of ethylene and tetrafluoroethylene monomers. Although not fully fluorinated, ETFE coating has excellent chemical resistance and can operate continuously at temperatures up to 300° F (149° C). ETFE is used frequently in the chemical processing industry because of its chemical resistance, permeation resistance, abrasion resistance, and electrical insulation—and its ability for high coating thickness builds.
Among fluoropolymers, ETFE coatings are the toughest. ETFE provides a variety of desirable protection properties for the ease of application and the cost. Color is also a deciding factor when choosing ETFE coatings. Green, and clear ETFE coatings can achieve the highest builds, while the white version of the coating is often used for medical and pharmaceutical applications.
Application Tips for ETFE
An ETFE coating is most often applied using a liquid primer and a powder topcoat—or multiple topcoats. Before coating, make sure you check all the corners and crevices of the parts you are coating. For proper adhesion, all welds need to be smooth and prepped well.
The mass or density of a part determines how much build is possible, and how much heat the metal parts retain. The white coating in particular causes application consistency issues with parts that have different thicknesses and masses.
One strategy is to heat the part up first to avoid “sagging” or “yellowing,” and maintain the correct temperature for the entire duration of the curing. If still having difficulty, heat your parts up more slowly so that the heat is evenly spread throughout the part. A final tactic is to rotate the part to reduce sagging even more.
ETFE vs. ECTFE
The names ETFE and ECTFE are similar, but that similarity can cause more confusion than is necessary. It might be easier to rename them E-TFE and E-CTFE because they are both copolymers with ethylene(E). E-TFE is a copolymer of ethylene and tetrafluoroethylene (TFE) monomers, and E-CTFE is a copolymer of ethylene and chlorotrifluoroethylene (CTFE).
ETFE and ECTFE polymers are both used commercially as the base resins for thick-film coatings used in the chemical processing industry. Overall, they have very similar performance properties. Both are good electrical insulators, have high use temperatures, and are good thermal conductors.
ETFE coatings are more thermally stable—and have higher temperature resistance—than ECTFE (also known as Halar® coating). On the opposite end of the thermometer, ETFE has lower temperature embrittlement. And while ETFE is FDA-compliant, ECTFE is not.
The main difference may come down to which chemicals will come in contact with the surface that you are coating, because both ETFE and ECTFE have vulnerability to certain chemicals. ETFE is affected by strong oxidizing acids, strong organic bases, and sulfonic acids at elevated temperatures. ECTFE is affected by acids, bases, and halogens at elevated temperatures; attacked by amines, esters, and ketones; and plasticized by halogenated solvents.
Because there are so many factors to consider with ETFE, ECTFE (Halar® coating), and other fluoropolymers, coating knowledge and application experience is invaluable. We have many experts here at Crest Coating, who have decades of experience, and we pull knowledge from many different areas. Fill out this quick form today and we can help select the right product for your job.