I haven't tried it but you might consider some of the flat waterproofing sprays for suede and other leathers. I was cleaning/treating some of the tables at the lake house and had some spray for leather (we have some leather topped tables). After reading the label, I decided it wasn't what I wanted for the tops but it is recommended as a spray on water proofing/stain proofing for suede and leathers. I can get the brand name later today if you need.
Lou