Further to my posting in 110719 MMDigest I would like to amend my statement
that burnt shellac is the only suitable sealer for lead tubing joints.
I remembered later that I was told by an experienced organ builder
that he uses Chatterton's compound.  This is a mixture of gutta-percha,
rosin and pine tar and comes in a convenient bar which is heated at the
end to release enough material for use.

Gutta-percha is a natural material derived from tree sap and, like
shellac, has thermo-plastic properties.  Electrical engineers will know
all about gutta-percha as it was used widely in cable insulation due to
its high dielectric properties.  It is also used in dentistry to fill
voids in root canal work.

If anyone knows where I can obtain some Chatterton's compound please
let me know.

Nicholas Simons, GB

 [ More at http://www.mmdigest.com/Archives/KWIC/C/chatterton_s.html
 [ -- Robbie