[Histonet] cryostat blues

[N Fournier]

Hi Everyone:

I am encountering problems with curling whenever I lift the antiroll plate and attempt to retrieve the section. Often the top portion of the section will remain flat while the bottom curls. I am sectioning fixed rat brains on a Vibratome Ultrapro 5000 cyrostat. The brains were placed in cryomolds and embedded in OCT, and stored at -80 degree C before sectioning.  The specimen isallowed to equilbrated in the chamber for 45 min before sectioning commences. The knife is new, and the specimen temperature is approx -13 to -15 degree, and chamber temperature at -20 degree C. The blade angle is currently set to around 2 to 3 degrees (as recommended by the manufacturer's instructions), however, this has been modified several times and the problem occurs at other angles.  

Does anyone have some suggestions of what could be causing this and most importantly what I could do to make it stop. 

Thanks,

Neil