Product Specifications: PC2021AB



Tough-Seal 21 is a tough and durable fast gelling Potting Compound and Sealant with excellent Thermal Cycling Stability. This medium viscosity material is self-leveling and flows like honey around electrical components to ensure complete coverage of your entire PCB or electronic assembly.


Tough-Seal 21 has a faster 10-20 minute working time and a Shore Hardness of 64A, which is similar to the hardness of a car tire. Tough-Seal 21 reaches 94% of its full hardness after an overnight cure or with a heat cure of 1 hour at 80°C (176°F). Tough-Seal does not exotherm or shrink during curing, therefore there is no embedment stress induced on the electronic components that could cause damage and failure of the PCB or electronic assemblies. Sensitive electronics can be potted safely with low embedment stress Tough-Seal.


With a high elongation of 225% when fully cured, Tough-Seal 21 maintains exceptional flexibility and thermal cycling stability from –40°C to 150°C (-40°F to 302°F) without pulling back, wilting, or cracking. This ensures a tough seal that will stop moisture or other contaminants from damaging sensitive PCB’s and electronics.


Tough-Seal has very aggressive adhesion to aluminum, making it a perfect choice for potting aluminum housings in LED lighting applications. Tough-seal bonds extremely well with most polymers. For housing and wire insulation materials that are exceptionally difficult to bond to, we offer our KEY PR1200 PRIMER, an aggressive adhesive promoter that is simple to use.

Technical Data Sheet (TDS) and Safety Data Sheet (SDS) Downloads

TDS (PC 2021AB)

SDS (PC2021A)
SDS (PC2021B)

TDS (Key PR1200 Primer)
SDS (Key PR1200 Primer)

(Typical Properties)
Physical Properties
Color, Part A Off White
Viscosityat 25°C, cP, Part A, (RVT #5, 20 RPM) 7,000
Specific Gravityat 25°C, Part A 1.32
Densityat 25°C, lbs/gal, Part A 11.0
Color, Part B Black
Viscosityat 25°C, cP, Part B,
(RVT #5, 20 RPM)
Specific Gravityat 25°C, Part B 1.28
Dielectric Constant,25°C – 60 Hz 5.75
Dissipation Factor, 25°C – 1 MHz 0.026
Dissipation Factor, 25°C – 1 kHz 0.028
Dissipation Factor, 25°C – 60 Hz 0.064
Heat CapacityCp, 25°C, J/g°K 1.37
Thermal Conductivity,25°C, W/m°K 0.26
seechart Coefficient of Thermal Expansion, ppm/ °C
(-) 65°C to 75°C 135
75°C to 100°C 0
100°C to 150°C 75
Coefficient of Thermal Expansion, ppm/°F
(-) 85°F to 167°F 75
167°F to 212°F 0
212°F to 302°F 42
Hardness vs Temperature
seechart (-75°C / -103°F) 88 A
(-25°C / -13°F) 75 A
5°C / 41°F 69 A
25°C / 77°F 64 A
50°C / 122°F 62 A
66°C / 150°F 61 A
80°C / 176°F 62 A
100°C / 212°F 57 A
120°C / 248°F 51 A
150°C / 302°F 47 A
Hardness vs Ambient Cure Time
seechart 1 hour 15 A
2 hours 26 A
4 hours 31 A
8 hours 35 A
12 hours 35 A
1 day 39 A
2 day 46 A
3 days 52 A
4 days 57 A
1 week 60 A
1 month 68 A
Mechanical Properties
Tensile Strengthper ASTM D638, 25°C, PSI 450
Elongationper ASTM D638, Type I, 0.125 in, 25°C 225%
Co=Cohesive Ad=Adhesive
Tensile Lap Shear Strengthper ASTM D1002, 25°C, psi **
metallica Aluminum Bare 540 Co
Steel Bare 530 Ad
Steel Ground 480 Co
Primed Steel 530 Co
Galvanized Steel 560 Co
Tin Plated Steel 470 Co
Chrome Plated Steel 560 Co
Tensile Lap Shear Strengthper ASTM D3163, 25°C, psi **
frp_text FRP – Polyester Fiberglass 540 Co
Garolite G-9 Melamine/Glass 530 Co
Garolite G-10 Epoxy/Glass 550 Co
Garolite XX Phenolic/Paper 570 Co
Tensile Lap Shear Strengthper ASTM D3163, 25°C, psi **
Thermoplastics_text Acrylic 560 Co
Acrylic/PVC 430 Co
PVC – Polyvinyl Chloride 530 Co
CPVC – Chlorinated PVC 660 Co
ABS – Acylonitrile Butadiene Styrene 500 Co
PETG – Polyethylene Terephthalate 610 Co
Lexan – Polycarbonate 520 Co
Nylon 6/6 – Polyamide 520 Co
Polypropylene 50 Ad
Polyethylene LDPE 20 Ad
Polyethylene HDPE 40 Ad
Teflon PTFE – Polytetrafluoroethylene 40 Ad
Noryl – Polyphenylene Oxide/Polystyrene 220 Ad
Ultem – Polyetherimide 540 Co
**20 mil Bondline, 1 in x 4 in Adherands, 1 in Overlap