Why are preservative solutions for preserving wet specimens (formaldehyde, kaiserling III…) yellow or blue at museums?


I’ve been googling for hours and can’t seem to find the correct key words to get the results I want. Are the newer solutions blue because it makes the wet specimens look more alive? What is the science?

In: 1

Typically, the specimen isn’t in formaldehyde, but it’s first “fixed” in formaldehyde (it chemically reacts to stop decomposition) and then placed in ethanol or isopropanol. Per this [NPS document](https://www.nps.gov/museum/publications/conserveogram/11-03.pdf), the yellowing is mainly due to dissolved proteins and lipids.

Ohh!! I see, thank you! Do you know why it is often blue?