Permeation resistance, another primary factor in chemical coating performance is a process by which a chemical can pass through a protective film without going through pinholes, pores, or other visible defects in the film. Individual molecules of the chemical enter the film and “squirm” through it, by passing between the molecules of the film and smaller molecules permeate the film quicker. In many cases the permeated material appears unchanged to the human eye. Chemical permeation can best be described in simple terms by comparing it to what happens to the air in a balloon after several hours. Although there are no pinholes or defects, and the balloon is tightly sealed, the air gradually passes through (permeates) its walls and escapes. This simple example uses gas permeation, but the principles are the same with liquids or chemicals. One way to offset permeation is by increasing film thickness.

FEP Teflon® ***

(Fluorinated Ethylene Propylene copolymer) coatings have superb release, and are frequently used as mold release coatings. They melt flow to smooth, non-porous films, and are thus more chemically resistant than PTFE coatings. FEP coatings have lower heat resistance (200°C [400°F]) than PTFE coatings but also cure at lower temperatures. FEP coatings are extremely non-wetting and have very low coefficient of friction.

PFA Teflon® *****

(Perfluoroalkoxy) coatings combine the high temperature resistance of PTFE with the melt and flow during baking characteristics to provide non-porous, chemical resistant films like FEP. PFA offers the additional benefits of higher continuous use temperature (260° C [500° F]) and a film thickness up to 1,000 micrometers (40 mils) and greater toughness than PTFE or FEP. This combination of properties makes PFA an excellent choice for a wide variety of uses, especially those involving chemical resistance.

Dykor® *****

Is a specialty line of Whitford dispersion coatings containing (PVDF). Because Dykor is unaffected by most chemicals and solvents, it is typically used to protect metals from harsh environments. This system is comprised of a primer, midcoat and topcoat and is used to line chemical process and storage vessels. Dykor has been the engineering polymer of choice for severe chemical applications for nearly three decades. Dykor forms a tough, abrasion resistant barrier that, if employed as recommended, will protect equipment for many years. Contact us to check your specific compatibility requirement.