[Cell-biology] Sf9 cells

[Allison]

I am starting to culture Sf9 cells and am growing them in Grace's Insect 
Medium, supplemented, +10%FCS + gentamycin.  According to invitrogen it 
should be possible to slough the cells off the plastic when it's time to 
passage them.  But the cells I have stick like crazy and do not want to 
come off that way.  Tapping the flask does not help.  I've tried 
scraping them off gently but the viablity (by trypan blue) is not great 
65-70%).  I would like better viability before going on to the virus 
infection step.

Any suggestions?

TIA
Allison