Hello Peter, thanks for your comments.

> Am late to this discussions but thought I might add a few comments.

Another cassette tape has now been in the silica treatment for only six
days, so there's no hurry. I've got several of them to go. :-)

> If you try the desiccant only method, it does take a few months.

My intention is just to get the audio content copied, there is no need 
to preserve
the tape and the cassette. It was possible to copy 35 minutes of the 
after just five days. If further treatment allows copying in sequences, 
I am happy.

> Also, you should seal the tape(s) with the desiccants inside an
> airtight container such as a double closure freezer bag.

I am using an airtight plastic freezing box, meant for freezing food stuff.
The tape spool is a bit loose, so it stays better together in a box than 
in a bag.

> If you seal the tapes in
> an airtight container, there shouldn't be any reason to
> replace/reactivate the silica gel.

Ok, thank you, this is good to know.
  Do you think there is any advantage to remove the tape from the shell 
to help
the desiccation process, or should it take the same time in a closed 
cassette shell?

Or, how about just removing the cassette shell cover?

Eero Aro