[pianotech] Contact Cement...was PVC-E yada yada

Chuck Behm behmpiano at gmail.com
Sun Jan 3 08:47:59 MST 2010


>Joe:
   There may be reasons why contact cement didn't work (and doesn't work)
for some folks.  1. You're right, the change to a non-petroleum based
adhesive yielded poor results.  DAMHIK.  Water base material is useless for
our purpose and should be avoided.  2. There is a difference in brands of
adhesive and which works best for our use.  Each tech will have to find what
that is.  3. Contact cement has a finite shelf life, the solvent will
eventually evaporate in the can resulting in eventual failure.  This can
occur using liquid, gel or spray materials.  It may have aged on the store's
shelf.   I remember having to do over a set I had just covered because of
this.  Fortunately the job had not left my shop yet.
   So yes, there are drawbacks to contact cement like most anything, but
don't broad brush the whole method as no good, when others seem to have good
results.
   Mike Kurta, RPT<

Thanks for your comments on this, Mike. The shelf life issue is something I
hadn't thought to mention which is extremely important.
When fresh, contact cement will pour freely. It begins to solidify with age,
and becomes gummy if it is allowed to sit on the shelf too long. At this
stage, it is useless and should be pitched.

I always buy my cement (I like DAP) by the quart can, which I then transfer
to the little bottles with the brush in the cap which are usually available.
(When pouring the glue from the can to the bottle, get a small stream going,
then stop about an inch from the top, or you will over-flow the little
bottle. Clean the rim of the can with the brush from the bottle.)

If the glue begins to gum up, discard it and buy new. I go through about 6
quarts a year, so it doesn't have the chance to get too old.

Also, I believe that you don't want to let the stuff freeze. I keep my shop
in the 65 - 70 degree range year round, so I don't worry about that, but if
your shop is only heated occassionally, keep you glues (contact cement,
Titebond, PCVE, whatever) and other important liquids inside. Chuck Behm
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