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.

Product Information Bulletin (PIB) and Safety Data Sheet (SDS) Downloads

PIB (PC 2021AB)

SDS (PC2021A)
SDS (PC2021B)

PIB (Key PR1200 Primer)
SDS (Key PR1200 Primer)

(Typical Properties)
Physical Properties
Color, Part AOff White
Viscosityat 25°C, cP, Part A, (RVT #5, 20 RPM)7,000
Specific Gravityat 25°C, Part A1.32
Densityat 25°C, lbs/gal, Part A11.0
Color, Part BBlack
Viscosityat 25°C, cP, Part B,
(RVT #5, 20 RPM)
Specific Gravityat 25°C, Part B1.28
Dielectric Constant,25°C – 60 Hz5.75
Dissipation Factor, 25°C – 1 MHz0.026
Dissipation Factor, 25°C – 1 kHz0.028
Dissipation Factor, 25°C – 60 Hz0.064
Heat CapacityCp, 25°C, J/g°K1.37
Thermal Conductivity,25°C, W/m°K0.26
seechartCoefficient of Thermal Expansion, ppm/ °C
(-) 65°C to 75°C135
75°C to 100°C0
100°C to 150°C75
Coefficient of Thermal Expansion, ppm/°F
(-) 85°F to 167°F75
167°F to 212°F0
212°F to 302°F42
Hardness vs Temperature
seechart(-75°C / -103°F)88 A
(-25°C / -13°F)75 A
5°C / 41°F69 A
25°C / 77°F64 A
50°C / 122°F62 A
66°C / 150°F61 A
80°C / 176°F62 A
100°C / 212°F57 A
120°C / 248°F51 A
150°C / 302°F47 A
Hardness vs Ambient Cure Time
seechart1 hour15 A
2 hours26 A
4 hours31 A
8 hours35 A
12 hours35 A
1 day39 A
2 day46 A
3 days52 A
4 days57 A
1 week60 A
1 month68 A
Mechanical Properties
Tensile Strengthper ASTM D638, 25°C, PSI450
Elongationper ASTM D638, Type I, 0.125 in, 25°C225%
Co=Cohesive Ad=Adhesive
Tensile Lap Shear Strengthper ASTM D1002, 25°C, psi **
metallicaAluminum Bare540 Co
Steel Bare530 Ad
Steel Ground480 Co
Primed Steel530 Co
Galvanized Steel560 Co
Tin Plated Steel470 Co
Chrome Plated Steel560 Co
Tensile Lap Shear Strengthper ASTM D3163, 25°C, psi **
frp_textFRP – Polyester Fiberglass540 Co
Garolite G-9 Melamine/Glass530 Co
Garolite G-10 Epoxy/Glass550 Co
Garolite XX Phenolic/Paper570 Co
Tensile Lap Shear Strengthper ASTM D3163, 25°C, psi **
Thermoplastics_textAcrylic560 Co
Acrylic/PVC430 Co
PVC – Polyvinyl Chloride530 Co
CPVC – Chlorinated PVC660 Co
ABS – Acylonitrile Butadiene Styrene500 Co
PETG – Polyethylene Terephthalate610 Co
Lexan – Polycarbonate520 Co
Nylon 6/6 – Polyamide520 Co
Polypropylene50 Ad
Polyethylene LDPE20 Ad
Polyethylene HDPE40 Ad
Teflon PTFE – Polytetrafluoroethylene40 Ad
Noryl – Polyphenylene Oxide/Polystyrene220 Ad
Ultem – Polyetherimide540 Co
**20 mil Bondline, 1 in x 4 in Adherands, 1 in Overlap