Strengths
What it’s good at
Underwater, marine, plumbing, and wet surface repairs — a hand-kneadable epoxy putty that cures underwater and seals leaking pipes, tanks, and drains.
Limits
Where it falls short
Non-structural on flexible substrates or polyolefin plastics (PP/PE). Cures off-white and requires thorough hand kneading to activate.
Specifications
Manufacturer specifications
Every number below is quoted from the manufacturer’s own documentation, linked at the end of the row.
- Working time
- 20 min — Knead and shape within 15–25 min before hardening begins[1]
- Initial set
- 25 min — Sets firm in 25 min at room temperature[1]
- Full cure
- 1 h — Functional cure in 1 h; allow 24 h before high-pressure service[1]
- Strength
- 4370 psi — Tensile strength according to ASTM D-638[1]
- Max service temperature
- 250 °F — Continuous service up to 250 °F (121 °C)[1]
- Water resistance
- Cures fully submerged in fresh or salt water; resists up to 500 psi water pressure[1]
- Food contact
- NSF/ANSI Standard 61 certified safe for potable drinking water systems[1]
- Cured color
- Off-white to pale grey[1]
How long it takes
Working time, clamp time, and full cure are different things — this is the order you experience them in.
- Working time20 min
- Initial set25 min
- Full cure1 h
Sources
Where these facts come from
- [1]J-B Weld WaterWeld Epoxy Putty Stick — product specifications and data sheet — J-B Weld · Manufacturer page · Retrieved 2026-08-13
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