We have imported a barrel varnish that wineries use in France. It is a clear water varnish designed to protect and decorate barrels and casks.
This protection doesn’t affect the wine and it protects the barrel while still allowing gaseous exchanges of water vapor and oxygen between the barrel and its environment.
Majority of wineries paint it on around the bung hole to prevent any mould from growing and to prevent wine stains so barrels still look neat.
Please contact me if you are interested