Hi

When spinning SU-8 2100 (at 1000rpm) I consistently get thicker than
expected layers. According to the datasheets, I should get 260um but I
get around 400um or more instead.
I am using silicon as a substrate and everything else is fine - I have
good adhesion and uniformity.
It's not a huge issue as I can always increase the speed but it seems
odd to have such a big variation. My SU-8 is quite old so perhaps I have
lost some solvent from it?