[Histonet] Pre-made paraformaldehyde question

[Suhyoung Jeong]

Dear Histo people,

In my old lab, I have been taught that 4% PFA has to be always made fresh
(maybe a day before max). Here in my new lab, I find that people use 32%
pre-made PFA from EMS (without expiry date) and only dilute it on the day of
use.

Does anyone have experience (or thoughts) with this issue?

Thank you in advance

All the best, Suh