G'day John and Alison;I did hear a rumour that bodhrans could be made more stable with a humectant -specifically "Guiness" - poured over the skin to maintain the correct dampness longer.
This remains a rumour (a Folk Myth?), as I have yet to meet the folkie (especially the type that plays Irish drums and music) that would contemplate pouring a Guinness anywhere but straight into the mouth.
Regards,
Bob Bolton