From time to time, it will be required that a piper dress his various leather fittings; a hinge, belting, valve pad, etc. I have made myself available of many of these treatments over the years. Many more than I care to recount. I recently tried an incredibly well made pair of boots from the esteemed Limmer Bros. of the northeast. (Vermont, New Hampshire, I don’t remember - those states are both the same anyway,) and I got a small tub of their boot grease enclosed in the order. It is, WITHOUT A DOUBT, the best leather treatment available. I don’t know what is in it, but I believe it is animal based, a little bit of beeswax, maybe some small percentage of silicone, and imbued with a subtile pleasant citrus finish as well. The recipe was not made available to me. It is wholeheartedly endorsed. I recommend it unequivocally. Use it sparingly. A little goes a long way.
Coolness. 
I’ve found this Shoe Grease to be truly excellent as well:
(Mother Huberd’s)
http://www.huberds.com/Home.html
“An apple a day, keeps the chickens away.” or, " If at first you don’t suck seed…keep on 'till you do suck 'em".
what kind of finish does it leave? is the citrus smell strong?
and…
“if at first you don’t succeed, keep sucking and see what happens..”
For these purposes, the application is best used sparingly, to moisten and lubricate the top grain fibers and prevent cracking from dryness, and will soften and darken most any leather. It will penetrate and leave no residue other than a soft sheen. Used in moderation, the scent is very mild, and dissipates in short order.
…so …for bellows that squeak upon compression (it’s the leather not the hinge that is making the noise) that should suffice? it leaves the surface smoothe? i.e. my squeaking ./creaking is coming from when the leather contacts itself, as it “grips,” hence the noise.
..think this stuff is the key?
I don’t think I would advise putting this stuff on the gusset. If you do, use only one drop over the whole thing! It will soften the leather, and that probably isn’t the best thing for the gusset. I once did a recording session and the engineer complained about a squeak in the bellows, as well as the sound of the valve clappers. I told him I would see what I could do about it, and I was rescheduled for the very next day, so went home and whipped up a gusset silencer out of an old t shirt. Just chopped it out and stretched it over the leather. Worked like a charm. Afterwards, I threw it away.
On a side note, years ago I went to the pub got a pint of Guinness and sat down to play, setting the pint next to me on the table. A beginning bodhran player came in, took off his coat, and tipped the pint over, miraculously spilling nearly all of it directly into the valve hole. I removed the valve, and poured it out, but within a half an hour, the gusset had undergone a total transformation, turning from leather into some kind of leather-based goop. David Quinn was kind enough to supply me with a new gusset, and gave me tips on sewing it in, and it became the first of many bellows I sewed in the years that followed. The publican mentioned later that some barmen in Ireland avoid wearing leather shoes because they have been known to immediately disintegrate.
Now THAT is the kind of repair work I’d like to learn: Gusset installation!
Seriously, now!
Ha, methinks not the first time something experienced a total transformation after half an hour of Guinness! I think I have transformed a few times that way…
I can’t say I’ve ever heard anything about Guinness dissolving leather! How wild!