Review on 📦 Dry & Dry Premium 20 Pack Reusable Humidity Indicator Cards (10-60%) – 6 Spot – Includes 20 Cards by Josh Jeffries

They work as advertised, I use them in sealed clear plastic containers to show when the silica gel inside needs to be regenerated. They turn from dark blue to pale blue and eventually start turning pink when the humidity is much higher than what is shown on the stain. However, they turn blue again when the humidity drops below the specified level. I've had 10-15 cycles so far and they're still working. Compared to other hygrometers they seem to be quite accurate. If you have used similar indicators in the past, be aware that direct sunlight, exposure to liquid water, and prolonged exposure to humidity levels of 90% or more will eventually cause them to stop working. Also note that the chemical that causes them to change color due to moisture is toxic. Minimize handling and avoid direct contact with food or edible items. From what I understand it's fine to keep them in the same container at ambient temperature - no direct contact -. I would give 5 stars if the map had "Reference" printed on it as it's difficult to see the "Lavender" point over time as they gradually shift. I have other cards that have a comparison block for this purpose and it would be really nice to have them. My solution is to keep a fresh silica gel card in a sealed bag for comparison.