That is normal, and as it should be. It goes a bit lighter green because the liquid inside has solidified and contracts slightly within the pore structure, making it appear a lighter shade.

No, unlike some other blood bag temperature indicators, Blood Temp can be stored at ambient temperatures and activated only when needed.

The expiry date is provided for each batch of products supplied. You will find it on a label on each box together with the batch coding we use for traceability.

The activation window gives an immediate confirmation that the indicator is armed as it turns from yellow to green. If this doesn't happen immediately, then fully re-squeeze the button between thumb and finger. The breach/indication window (white with a red border) is separate so that you can clearly see if there has been a breach of the 10ºC/50ºF temperature threshold. If no breach has occurred the window will remain white. It will turn blue if there is a breach.