What is seasoning?

(NOTE: Synthetic bags should never be seasoned.  Seasoning will plug the pore structure of Gore-Tex and prevent moisture transport.)

Let's start with what a bag must do.  To allow the instrument to play, the bag must be air-tight - in the short term.  To keep everything from molding and mildewing, moisture must be able to escape - in the long term. 

Seasoning is a material that is applied to the inside of hide and sheepskin bags to:

• seal larger holes (by plugging or swelling), thus keeping it air-tight,
• facilitate the transport of moisture, thus preventing mildew and mold,
• keep the bag flexible .

It is generally either a sugar and/or protein based material to plug larger holes (e.g., Airtight, or other mixtures with egg, honey and/or treacle) or a hydrophilic based liquid that swells the leather (e.g., Titan, glycerol, isopropyl alcohol).  Any of these materials will also absorb some moisture and transport it from the moist inside of the bag to the walls where it can evaporate.

Some people have proposed using lanolin and other animal/vegetable oils and greases.  The presence of these  hydrophobic ingredients in seasoning will inhibit moisture transport and may aggravate mildew and mold growth in the bag.   These mixtures may work acceptably on a bellows blown instrument where moisture transport is not an issue, but would be expected to be problematic in a mouth blown instrument.

Cow/elk hide  bags do not always need an initial seasoning. Generally seasoning a new bag is needed only if the bag  leaks through the pores or seams or if it continues to feel very stiff after playing for a couple days.  The pores in sheepskin are larger which means that the bag is inherently less air-tight, but these larger pores can transport more moisture making the sheepskin bag better for a humid, damp climate.  Hence, sheepskin bags will usually need an initial and more frequent seasoning. 

Leather bags should be re-seasoned when the bag starts to leak. 

After seasoning a bag, never leave the excess in the bag.  Any excess seasoning should be completely drained or it will get on reeds and/or restrict the migration of water from the bag.

I can find no scientific rationale for putting whiskey in the bag. The idea of killing mildew has been proposed, but a well seasoned bag does not suffer from this kind of problem. Mildew is the result of excessive moisture retention.  Allowing the bag to dry (i.e., by removing the blowstick when not in use) would kill any mildew.

If you can add more on this topic, please contact me.