Take from The irish pipers' society postings:
mix it since many years by myself. At first for mouth blown pipes and later for the Uilleann Pipes.
It consists mainly of water. Gelatine (200 ml) makes it air tight. The second important ingredient is glycerine, may be two or three soup spoons full. This would be enough to reach the target to tighten the bag and to make the leather soft.
Then I add sugar, may be 100 gr, which kills bacteria and protects from rotting. Then I also add Aspirin (Acidum acetylosalicylum), which is not really necessary for the Uilleann Pipes because no breathe humidifies the bag, but it may help.
Raise temperature but do not exceed 50 °C. Fill in the slightly warm gelatine pudding as a fluid. Let it cool down and let drop off all left over fluid.
With corks locked the bag should be tight now like a football.
With this method I own now the second bag of my Uilleann Pipes, which Andreas made round about 1985. And I exchanged the bag not because it was bad, but of colour reasons.
Christian Tietje
I it old English? Adrian