After all the long thread about various glues, I feel I must add my
two cents worth.  I have been deeply involved in the audio, sound and
loudspeaker industry for over 45 years.  I have worked for two major
manufacturers of loudspeakers: (1) Altec Lansing, one of the very
first, in 1938 when it was part of Western Electric, and (2) Dukane
Corporation, who made some of the earliest radios, including their
loudspeakers, late 1920's early 1930's.

At both of these companies the adhesives used to assemble loud-
speakers were the "black magic" of the manufacturing process.  Only a
few companies actually formulated the adhesives.  This technology has
constantly improved over the years and thus the quality of the end
product has greatly improved, stayed together and endured higher levels
of sonic stress.

The point here is that adhesives used by industry are NOT usually
off-the-shelf items.  In most cases they are specifically formulated
to match the characteristics of the two materials being joined.  Their
composition, porosity, surface roughness, etc.

The actual adhesive is also formulated to provide a working time before
set-up, viscosity, flow and spreading characteristics and the durometer
readings and flexibility (rigidity) after complete cure.  In some cases
cure occurs because of the addition of oxygen, removal of air or
oxygen, application of heat, removal of heat, application of ultrasonic
energy, application of infrared energy, application of RF energy.

The development of these adhesives is done by the product manu-
facturer interactively with the adhesive formulator (read 'chemist').
The adhesives we see in the hobby shops, hardware stores, woodworking
stores, etc., are all a sub-set of the "professional adhesives used by
industry.  They are SAFE and easy to use (most always give good a
result).

There are many choices in the market place.  For the best result
determine by trial and error and the experienced recommendations
of others which adhesive will best hold your two pieces of "stuff"
together.  Talk with the adhesive manufacturers about products and
various formulations.  There are both consumer and professional
versions of contact cement and similar solvent based adhesives.
They are very different is ease of use and performance.

It is interesting to see the many ideas and experiences that have
appeared in the "glue" thread.  Perhaps someone would like to get
some input from the actual manufacturers.

Just some thoughts,

John Lanphere

P.S.:  Here is an interesting website for the selection of adhesives.
       Look at  http://www.thistothat.com