Formvar Wire insulations and coatings

Datasheet updated

2022-05-10 07:47
(supersedes all previous editions)

Formvar enamel is made from vinyl acetal resins produced as a smooth uniform film. Formvar has excellent mechanical properties such as abrasion resistance and flexibility. The film will withstand excessive elongation without rupture. When stressed during winding, Formvar has a tendency to craze upon contact with solvents such as toluene, naphtha, xylol, etc. Formvar can be removed mechanically or chemically during terminal preparation.

Typical applications are within motors, random and precision wound coils, oil filled and dry transformers, armature and generator winding where "tough" film may be required.

Electrical properties

Property NEMA MW-1000 ASTM D1696 IEC 851 JIS C 3003 MW-15-C
Dielectric strength at 25°C (77°F) 69-75 13-4.2, 3, 4 11.1 13.1 kV
Dissipation factor at 220°C (428°F) 107-114 0.05

Mechanical properties

Property NEMA MW-1000 ASTM D1696 IEC 851 JIS C 3003 MW-15-C
Adherence and flexibility
no snap
20% snap




Pass 1d
Pass 1d
% elongation at break 122-129 6-3.0 36
Mandrel at break 122-129 Pass 1d
Cut-through temperature 61.68 261°C (502°F)
Heat shock
20% stretch - ½ h at 200°C (392°F)




Pass 3d

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.