Check the listing for details. Cobalt Chloride ~ 1 Vial of 100 Test Papers. Condition: New. Listed at 9.99 USD. Bartovation (Made in USA) Cobalt Chloride Test Paper One order = 1 vial with 100 Strips. If you need multiple vials, buy more than one. Our Cobalt Chloride test paper detects the presence of moisture to determine if you have wetness or dampness problems. The Cobalt Chloride test paper is useful in difficult to reach places and recesses, such as cracks in circuit boards or ceramics. Cobalt chloride test paper is responsive to 50% relative humidity and above, and any direct measure of an aqueous solution. Instructions: Place the test strip or sheet near recesses or areas where there may be cracks/leaks. If moisture is present, the test paper will turn from blue to a light pink/white color. NOTE: Be sure to keep the strips sealed tightly in the vial, as exposure to 55 percent relative humidity or greater is sufficient enough to cause a slow color change. In addition, if the sheets are heated or the surrounding air dries, the paper will change back to its original blue color.