Glossary of Terms

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Partial cure:
Process sometimes utilized when multiple layers of fluoropolymer coatings are to be applied. The first coat is incompletely cured; the second coat is applied and both are fully cured together. See Flashing.

Pencil hardness:
A value determined by measuring the relative hardness of a coating based upon the ability of the coating to resist penetration and gouging by pencil lead of varying hardness. The order of pencils from softest to hardest is 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, and 8H. The hardness rating of the coating is equal to the first pencil which does not penetrate and gouge the coating when tested from softest to hardest.

PFA (perfluoroalkoxy):
Thermoplastic member of fluoropolymer family of engineering plastics, one characterized by excellent release, low friction and toughness.

pH:
An expression of the degree of acidity or alkalinity of a substance expressed as a number from 0 to 14. Neutrality is pH7. Acid solutions are less than 7 and alkaline solutions are greater than 7.

Phenolic:
A resin or plastic, usually thermosetting, made by condensation of a phenol with an aldehyde and used for molding, insulating, coatings and adhesives.

Phosphating:
Surface pretreatment used on ferrous parts that provide a very thin crystalline film that enhances both corrosion resistance and adhesion.

Pigment:
Finely divided, insoluble colored substance used to impart color to a coating.

Plasma deposition technique:
A method of applying powder using compressed gas and melting the powder in a flame before the powder impinges on a surface. Polymer fume fever: An illness characterized by temporary flu-like symptoms caused by inhaling the products released during the decomposition of fluoropolymers.

Post-cure:
A second cure at high temperature to enhance specific properties such as release and non-wetting.

Powder coatings:
Finely divided particles of organic polymers, pigments and additives alloyed to form a coating.
Powder metal: Material formed by compressing particles of metal and heating (sintering) to solidify and strengthen them.

Preheating:
Warming of parts prior to application of a coating, recommended when adhesion is critical and when parts are being coated in humid atmospheres. In some cases, this technique can be used to achieve higher-than-normal film builds.

Preloads (for fasteners):
The "tightness" of a fastener, equal to the make-up energy applied minus the energy required to overcome friction at the fastener's bearing surfaces and threads.

Pressure spraying:
Coating technique similar to siphon spraying, except that the coating is delivered from a pressurized pot to the spray nozzle under positive pressure. Generally used for high-volume production.

Pretreatment:
Processes for cleaning and conditioning a substrate to be coated. Next to the choice of coating, this may be the most important factor in the use of high-performance coatings.

PTFE (polytetrafluoroethylene):
A thermoplastic member of the fluoropolymer family of plastics. PTFE has the lowest coefficient of friction of any known solid and the highest operating temperatures of the fluoropolymers.

PV, limiting PV (LPV) factor:
Mathematical limit of a coating's load-carrying ability and wear resistance under bearing conditions.

PVDF (Polyvinylidene fluoride):
High-molecular weight thermoplastic of vinylidene fluoride with excellent strength, wear resistance and creep resistance.