I have the same problem and you may keep for 2h before use it.

On Sat, 30 Apr 2005, Jiang Ziling wrote:

>  I am using Su-8 and frequently there are air bubbles left in the
> film after spin coating. It is more serious with thicker films. I
> tried to get rid of them by putting the pre-spinning resist-coated
> wafer in vacuum dessicator, but the bubbles won't go. Anyone have
> experience in this?