[Histonet] dehydration time for a relatively large sample

[Rui TAHARA]

Hi, 

I am wondering if prolong dehydration time with 95 and 100% ethanol would brittle the sample for paraffin sectioning. 

I have been trying to section adult zebra finch beak and processed several samples, however, 
i failed to obtain a good section. It appears that the paraffin did not penetrated the tissue. This may be derived from incomplete dehydration and clearing before paraffin. 
Because i have read somewhere that if the sample was sitting in 95 and 100% ethanol too long it would be brittle and be teared when sectioned.  I have processed only a beak (about 1 cmX0.5 mm). 
Also when is an appropriate time to use vacuum? I am afraid that if i used it at 100% ethanol, the ethanol would evaporate....

so far I have tried; 
fix overnight
decalcified few days
walk from water to 70% ethanol; overnight 
85%, 95% (2times change)  and 100 % (2 times change) ethanol; overnight   
clearing; 2 days
paraffin (2 times change); overnight

Any suggestion would be appreciated. 
Thank you in advance, 

rui