Synthetic Rubber 1B51
Model No: 1B51

HumiSeal® 1B51 Synthetic Rubber Conformal Coating is a one component, fast curing synthetic rubber coating that is used for circuit assemblies and can be easily repaired. It offers low moisture vapor permeability, flexibility, low stress on components, unique base polymer, moisture and environmental protection. It can be applied by spraying, brushing, or dipping methods.

 Product Enquiry

HumiSeal® 1B51 conformal coating is:

  • a fast drying
  • single component
  • synthetic rubber
  • used in combination with Thinner 535/521/521 EU


HumiSeal® 1B51 conformal coating has:

  • excellent moisture and environmental protection for printed circuit assemblies
  • extremely low moisture vapor permeability
  • excellent flexibility, enabling low stress on components
  • full compliance with the RoHS Directive 2015/863/EU
  • recognition under UL File Number E105698


Application of HumiSeal® 1B51

Conformal coatings can be successfully applied to substrates that have been cleaned prior to coating and also to substrates assembled with low residue “no clean” materials.  Users should perform adequate testing to confirm compatibility between the conformal coating and their particular assembly materials, process conditions and cleanliness level.


Product Specification

Density, per ASTM D1475

0.89 ± 0.01 g/cm3

Solids Content, % by weight per Fed-Std-141, Meth. 4044

22 ± 1.5 %

Viscosity, per Fed-Std-141, Meth. 4287

185 ± 30 centipoise


694 grams/litre

Drying Time to Handle per Fed-Std-141, Meth. 4061

10 minutes

Recommended Coating Thickness

25 – 75 microns

Recommended Curing Conditions

24 hrs @ RT or 30 min @ 76°C

Time Required to Reach Optimum Properties

7 days

Recommended Thinner (dipping & brushing)

HumiSeal Thinner 535

Recommended Thinner (spraying)

HumiSeal Thinner 521, 521EU

Recommended Stripper

HumiSeal Stripper 1080, 1080EU

Shelf Life at Room Temperature, DOM

18 months

Thermal Shock, 50 cycles per MIL-I-46058C

-65°C to 125°C

Coefficient of Thermal Expansion – TMA

55 ppm/°C

Glass Transition Temperature – DSC


Modulus – DMA

93.1 MPa @ -20°C73.5 MPa @ 0°C35.3 MPa @ 20°C

Moisture Vapor Transmission, per ASTM E398-03

<1 g/m2·day·mil

Dielectric Withstand Voltage, per MIL-I-46058C

>1500 volts

Dielectric Breakdown Voltage, per ASTM D149

4900 volts

Dielectric Constant, at 1MHz and 25°C per ASTM D150-98


Dissipation Factor, at 1MHz and 25°C per ASTM D150-98


Insulation Resistance, per MIL-I-46058C

2.0 x 1014 ohms (200TΩ)

Moisture Insulation Resistance, per MIL-I-46058C

1.0 x 1010 ohms (10GΩ)

Fungus Resistance, per ASTM G21