Seasoning is used in mouth- blown pipe bags to keep the bag airtight, to absorb moisture and let this moisture breath out through the leather. It also stops the leather stiffening or rotting and contains fungicide and biocide which helps combat some of the possible fungal growths that can occur.

It is not possible to state how often you should season your bag. This is dependent on the type of leather, the amount of playing you do and whether you are a “wet” or “dry blower. For most pipers this will probably mean seasoning every 5-10 months.

There is a variety of  suitable proprietary  'Hot' type of seasoning  available online for Highland pipes.  I suggest that you use Hardies Airtight, and follow these instruction, rather than what is written on the bottle. 

Open the container and place in a saucepan of water and simmer until the seasoning is liquid. Remove the drones and chanter and put them well out of the way, where they cannot roll off the table and reeds get damaged. It is prudent to stop up the stocks with old corks to stop any seasoning dripping out over the outside of the bag. (Sherry corks often fit- you can use masking tape around them if they are too small). Make a rolled tube of paper to line the blowpipe stock to prevent the seasoning getting on the inside of the stock. Wait until the seasoning has cooled to about blood temperature, but has not begun to set again, and pour in a small amount down the blowpipe stock. About half an egg cup full should be fine. Now rub the bag so that the entire inside surfaces are lightly coated. Keep rubbing the inside surfaces against each other and “work” the seasoning into the seam and leather- especially the area beneath the blowpipe. This is the area where the seasoning tends to wash off if you are a wet blower.

Now leave the bag for a couple of hours for the seasoning to set.

If traces of seasoning are left on the inside of the stocks you can clean them with rolls of newspaper or damp tissue. Before reassembling you could coat the inside of the stocks with a very very thin layer of Vaseline to prevent the hemp sticking. Do not start playing for several hours.

Normally when seasoning a bag you only would need to apply one coat. However if you think it requires more seasoning repeat the process after over 8 hours.  Applying two light coats of seasoning is always more satisfactory than applying one heavy coating. This can lead to clots forming inside the bag which can sometimes blow onto the reeds. These can be a nuisance, but do not damage the reeds and can be easily removed. If you feel that you have poured too much seasoning in hold up the bag to let the surplus drain out through the chanter stock.