Phone Icon0208 953 1211       Email

Cart empty

HumiSeal 1A20 Urethane Conformal Coating

HumiSeal® 1A20 is a single component, chemically resistant, fast curing polyurethane conformal coating. HumiSeal® 1A20 fluoresces under UV light for ease of inspection. HumiSeal® 1A20 coating is MIL-I-46058C qualified, IPC-CC-830 and RoHS Directive 2002/95/EC compliant and recognized under UL File Number E105698.
Manufacturer: Humiseal

Properties of HumiSeal® 1A20

Density, per ASTM D1475 1.02 ± 0.02 g/cm³
Solids Content, % by weight per Fed-Std-141, Meth. 4044 50 ± 3 %
Viscosity, per Fed-Std-141, Meth. 4287 100 ± 30 centipoise VOC 511 grams/litre Recommended Coating Thickness 25 - 75 microns Drying Time to Handle per Fed-Std-141, Meth. 4061 60 minutes
Recommended Curing Conditions 24 hrs @ RT or 3 hrs @ 76°C Time Required to Reach Optimum Properties 7 days
Thinner, if needed (dipping, brushing, spraying) HumiSeal® Thinner 521, 521EU Recommended Stripper HumiSeal® Stripper 1072
Shelf Life at Room Temperature, DOM 6 months Thermal Shock, per MIL-I-46058C -65°C to 125°C Coefficient of Thermal Expansion - TMA 515 ppm/°C Glass Transition Temperature - DSC 71°C
Modulus - DMA 89.6 MPa
Flammability, per UL94 V-0
Dielectric Withstand Voltage, per MIL-I-46058C >1500 volts
Dielectric Constant, at 1MHz and 25°C per ASTM D150-98 3.5
Dissipation Factor, at 1MHz and 25°C per ASTM D150-98 0.028
Insulation Resistance, per MIL-I-46058C 3.0 x 1014 ohms (300TΩ) Moisture Insulation Resistance, per MIL-I-46058C 4.8 x 1010 ohms (48GΩ) Fungus Resistance, per ASTM G21 Passes
Resistance to Chemicals Excellent

Application of HumiSeal® 1A20

Cleanliness of the substrate is of extreme importance for the successful application of a conformal coating. Surfaces must be free of moisture, dirt, wax, grease, flux residues and all other contaminants. Contamination under the coating could cause problems that may lead to assembly failures. Although its formulation allows HumiSeal® 1A20 to be applied using a wide variety of methods, care should be taken to ensure that it is only applied in an environment where the ambient relative humidity is at 60% or less. Application of the coating when
the RH is higher than 60% can cause acceleration of the cure reaction, resulting in bubbles in the dried film.


Depending on the complexity, density and configuration of components on the assembly, it may be necessary to reduce the viscosity of HumiSeal® 1A20 with HumiSeal® Thinner 521 or 521EU in order to obtain a uniform film. Once optimum viscosity is determined, a controlled rate of immersion and withdrawal (5-15 cm/min) will further ensure even deposition of the coating and ultimately a uniform film. During the application, evaporation of solvent causes an increase in viscosity that should be adjusted by adding small amounts of HumiSeal® Thinner
521 or 521EU. Viscosity in the dip tank should be checked regularly, using a simple measuring device such as a
Zahn or Ford viscosity cup


HumiSeal® 1A20 can be sprayed using conventional spraying equipment. Spraying should be done in an environment with adequate ventilation so that the vapour and mist are carried away from the operator. The addition of HumiSeal® Thinner 521 or 521EU is necessary to ensure a uniform spray pattern resulting in pinhole- free film. The amount of thinner and spray pressure will depend on the specific type of spray equipment used and operator technique. The recommended ratio of HumiSeal® 1A20 to HumiSeal® Thinner 521 or 521EU is 5:2 by volume; however the ratio may need to be adjusted to obtain a uniform coating.


HumiSeal® 1A20 may be brushed with a small addition of HumiSeal® Thinner 521 or 521EU. Uniformity of the film depends on component density and operator's technique.


HumiSeal® products may be stored at temperatures of 0 to 35°C. HumiSeal® 1A20 should be stored away from sunlight and excessive heat, in tightly closed containers. If coatings are partially used, the container should be purged with dry nitrogen prior to resealing. Prior to use, allow the product to equilibrate for 24 hours at a room temperature of 18 to 32°C.


Application of HumiSeal® Conformal Coatings should be carried out in accordance with local and National Health and Safety regulations.
The solvents in HumiSeal® 1A20 are flammable. Material should not be used in presence of open flame or sparks. Use only in well-ventilated areas to avoid inhalation of vapours or spray. Avoid contact with skin and eyes.

Consult MSDS/SDS prior to use.



Conro Electronics Ltd
Unit 7, Orbital 25, Dwight Road, Watford, Hertfordshire
WD18 9DA

delivery van icon


We offer next day and Saturday deliveries excluding orders made after 3pm weekdays, weekends and public holidays.

AS 9120B

Conro Electronics Ltd certified to the AS 9120B (Aerospace) standard

Click Here To View Our Certificate

ISO 9001:2015

Conro Electronics Ltd certified to ISO 9001:2015

Click Here To View Our Certificate