Please congratulate your wife on her castor oil finding.
I decided after a lot of research to take part in trying out the castor oil pack.
I put castor oil on the flannel, put the flannel on my belly and then wrapped myself in cling film. This meant I didn't have to worry about mess. I then did my hot water bottle and layed on the sofa for an hour but not completely flat.
I then went to bed and I couldn't get to sleep on my back so I laid on my side, I was also wearing a swimming costume in order to keep the hot water bottle in place.
I couldn't sleep with the hot water bottle either so I just slept normally (on my side) until morning.
My long rambling question is do you think that would still work or does it need to stay heated?.