Cobalt Chloride Water Leak Indication Paper

SKU: 33813-Co8

$2.50USD or lower Each

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[4.8]   3 Reviews    | Write a Review

Indigo® cobalt chloride paper indicates water moisture under roof shingles & floor tiles or shows spray patterns inside car doors. Even small amounts of water vapor can damage sensitive products. At 55% relative humidity, cobalt chloride changes from blue to light pink. At the highest relative humidity levels, color change is rapid and immediate when exposed to liquid water. Single sheets start at $2.50 with discounts for quantity. See Water Leak Testing Paper for 100 short precut strips.
  • 8x10" (200x250mm) cobalt chloride moisture detection paper
  • Reacts at 55% RH; instantly with liquid water
  • Changes from blue to light pink; reversible
  • Shelf life 3 years if kept sealed; 5 years is typical.
  • Watch our video Water Leak Problems?
  • Certificates of Analysis, Stability & SDS on-line; see Specifications
  • Price breaks on volume; immediate delivery

See blogs: Water Leak Detection-Leaky Roofs & Find Water Leaks Fast: Cars, Boats, Roofs

For the chemically curious:

  • Cobalt Chloride: Colorful Moisture Detector for more information on the chemistry of CoCl.
  • The anhydrous form of cobalt chloride, CoCl2, has a blue color. The pink color is cobalt chloride hexahydrate CoCl2.6H2O. You can see the structure of CoCl2in our 3D Molecular Model Builder but you have to enter it as cobalt chloride. The pink color is CoCl2.6H2O or cobalt chloride hexahydrate. Enter cobalt chloride hexahydrate in . The model is intended mainly for organic compounds & doesn't render the structure properly.


In Kits
33813-WS8Water Leak Sheet Sample Pack 8x10", 3 pk1
  • Sheet dimension is 200x250mm or 8x10"; custom sizes available
  • Reaction with water vapor (<100%RH) is slow and can be reverted back to blue if heated or dried.
  • If splashed, color change to white is immediate and irreversible.

Test Paper Documentation

Stability Statement Certificate of Analysis SDS
Indigo Cobalt Chloride Sheet 200x250mm Stability Statement Indigo Cobalt Chloride Sheet 200x250mm Certificate of Analysis SDS Sheet
Reviews (3)

Exactly what I was looking for to check for roof leak in a vacation home.

— jc
— Indigo:

Glad we could help solve your problem. Thank you for the Review. If you want to know a bit more about the different leak detection sheets, check out: Find Water Leaks Fast: Cars, Boats, Roofs, Plumbing


Been stymied by a small leak in a drain pipe in my home for some time - finally ordered these water detection sheets and voila - was able to pinpoint the location of the leak and have the plumber repair quickly. These sheets work great - I think every plumber in America should have them available to help locate pesky leaks - thanks for the great product and helping me solve my annoying little problem.

— Allen
— Indigo:

Thanks for the feedback. That's an interesting suggestion about essential plumbing supplies. Perhaps this might offer them better insight: Find Water Leaks Fast: Cars, Boats, Roofs, Plumbing



Good. Received in speedy fashion and well protected from the elements so the paper would not react before getting to NZ.

— Mark
— Indigo:

Glad it got there ok. Interestingly, moisture incurred during long journeys has been a frequent question from industrial customers.

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