The hotplate does seem to improve bonding a lot.
I now use the HCl treatment prior to oxidation, methanol (for alignment
between glass and PDMS), and hotplate at 85C. So far 100% success!
Thanks for all the tips.

Gareth

Ali Bhagat wrote:
> Yes Bala, bonding occurs almost immediately after the surfaces get into
> contact. After coming in contact, place the device on a 85C hotplate for
> about 2 hours to get good results.
>
> -Ali-