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General Properties of Formvar

Formvar is a synthetic enamel composed of polyvinyl acetal and phenolic resins. Formvar's hot oil resistance sets it apart from all other magnet wire insulations. The flexibility, adhesion and abrasion scrape resistance of Formvar film is excellent. Its electrical properties are very good and it is resistant to common solvents.

Guitar Pickup Winding Wire for Warmth and Note Definition...

Formvar serves as an excellent choice of winding wire for pickup manufacturing companies and it is chosen for it's resistance to common solvents (including sweat and other liquids that can find its way into a guitar's pickup cavity). Heavy Formvar is used where top end brightness and note definition and clarity are desired attributes, since fewer turns are possible due to the thickness of the insulation. A certain famous guitar maker used Heavy Formvar in their single coil pickup windings throughout the early 1950's and 1960's. This is the best choice for period-correct, authentic single coil pickup winding wire.

General Properties of Plain Enamel

Plain Enamel magnet wire is insulated with a synthetic resin enamel. It is the oldest of the film insulations and all basic properties are good. Relatively easy removal of film by mechanical or chemical means. Good moisture resistance.

Excellent Windability...

Heavy Poly Nylon Round Magnet Wire

HPN combines the magnet wire insulation characteristics of Heavy Poly with the advantages of a nylon topcoat. With the nylon, HPN is still readily solderable, yet the solvent resistance and thermal stability of the insulation is excellent. In addition, the nylon provides improvement in the windability and tolerates more severe winding operations. HPN is an excellent choice for automatic winding machines. Heavy Poly Nylon's heavy coating is an excellent choice for vintage-voiced pickup wire.

Vintage Tone...

Plain Enamel is a magnet wire insulation type used in vintage pickup windings and today is used in vintage reissue guitar pickups. Plain Enamel is often defined visually by it's dark purple / brown-ish tint. Don't be fooled by companies that tint and dye other insulation types as a substitution for the real deal; supply is limited for plain enamel since it is mostly used in smaller quantities by pickup winding companies in vintage-spec'd guitar pickups.
Unit of Measure



N/A Formvar


N/A Vintage Magnet Wire

AWG Size

N/A 42

Min. Bare Wire Diameter

N/A 0.0024 in0.061 mm

Nom. Bare Wire Diameter

N/A 0.0025 in0.064 mm

Max. Bare Wire Diameter

N/A 0.0026 in0.066 mm

Min. Increase in Diameter Due to Film Coating

N/A 0.0004 in0.010 mm

Min. Overall Diameter of Film-Coated Wire

N/A 0.0028 in0.071 mm

Max. Overall Diameter of Film-Coated Wire

N/A 0.0032 in0.081 mm