SynChem – Resins & Varnishes Synthite AC-43 Air drying varnish

Synthite AC-43 is a clear, air drying electrical insulation varnish on basis of modified polyester, suitable for class H.

Synthite AC-43 has the following excellent properties:

  • UL-approved
  • very fast air drying
  • excellent chemical resistance
  • solderable
  • excellent adhesion
  • good penetration
  • transformer oil resistance ASTM D 155-55
  • corrosion and humidity resistance
Download datasheet


Typical applications for Synthite AC-43 are:

  • stators
  • printed circuit boards
  • form wound coils
  • resistors
  • transformers
  • capacitors


Class H (180 °C) UL-file-no. OBOR2.E317427 and OBJS2.EB17429.

Magnet wire Twisted pairs Helical coils
MW 24-C 155 °C 155 °C
MW 28-C 130 °C 130 °C
MW 35-C 180 °C 180 °C





Delivery forms

Colour: clear
4.5 kg, 22.5 kg and spray bottles on request.


Synthite AC-43 can be stored at room temperature and in closed containers for up to 36 months (max. 30 °C). The varnish has to be stored in cold, dry places, protected against direct sunlight.


Air drying time (on copper plate):
10 min. - set to touch
Baking of 20-30 min. at 150 °C will provide a film with optimum toughness and bond strength.


Use in well ventilated area, aboid contact with skin and eyes and wear protective clothes. Please observe the safety data sheet.


Synthite AC-43 may be applied by dipping, brushing or spraying as supplied.
For fast conveyor application, the following cycle is recommended:
1. Preheat units for 10 min. at 110 °C
2. Dip into the varnish for 30 sec.
3. Drain 10-20 min.
4. Bake 60-90 min. at 110 °C
For this type of cycle Synthite AC43 should be diluted 10-15 % with Dolph's® T-200 thinner.

Technical data

Property Unit of measure Conditions Values Test method
Coating thickness µm 75-100 ASTM D-115-55
Property Unit of measure Conditions Value Test method
Dielectric strength kV/mm dry / 0.025 mm film thickness 80 ASTM D-115
Dielectric strength kV/mm after 24h water storage / 0.025 mm film thickness 48
Creep resistance CTI 600 M IEC 60112
Property Conditions Blistering Rusting Cracking Test method
Resistance Water no no no ISO 4628/2-3-4
Resistance 10 % Sulfuric acid no no no ISO 4628/2-3-4
Resistance 1 % Sodium hydroxide no no no ISO 4628/2-3-4
Resistance Salt water no no no ISO 4628/2-3-4
Liquid phase
Property Unit of measure Conditions Values Test method
Viscosity s 25 °C 50-70 ISO Cup 4
Viscosity s 25 °C 18-24 Ford Cup 4
Specific density g/l 25 °C 900±30