Hello everyone,

I want to ask something about KOH etchant to those of you who are familiar with
it.

We have KOH etching bench in our cleanroom, in that bench, there is an etchant
tank.
So we keep the KOH etchant in the tank, which means it is always exposed to air
(even though we have a cover).

One day, when I took a look at it, surface of the etchant were solidified, the
surface looked like a milky jelly.
But when I heated up the 90C, now it looked like normal(clean, transparent).

So, I wonder this is normal condition or something wrong with etchant.


Thank you