Leaking Bellows Cloth or Bad Seal?
Hi All, Had I not encountered the same problem in two different
devices in one week, I would most likely not be writing. However,
the following problem was so severe and so deceiving that I feel it
deserves mention in the MMD.
The problem seemed to be leaking bellows cloth. However, I found that
the real problem was the cloth-to-wood glue seal. What was deceiving
was evidence that a good seal did exist, i.e., there was a bead of
glue that had squeezed out from between the wood and the cloth when
the cloth was pressed onto the wood.
I finally discovered the true nature of the problem when I applied
Phenoseal to the area where the wood and cloth met and then forced air
(by sucking) between the cloth and the wood. What I saw was lots of
tiny bubbles (see picture).
Since the cloth was heavy weight bellows cloth with the fuzzy back,
here is what I believe happened. When the glue made contact with the
fuzzy back, the moisture quickly soaked into the cloth and even
squeezed out a bit. However, it didn't saturate the cloth (and/or the
wood). This left hundreds or maybe thousands of microscopic voids
through which air could easily pass, making it appear that the cloth
How can this problem be eliminated? Double check the seal before
considering the job done. I explain the procedure I use -- which I
learned from Craig Brougher -- in a new web page called "Recovering
Bellows". It is located at:
Basically, you apply the glue, set the cloth, and then quickly remove
the cloth and check for voids. Keep doing this until there are no more
voids. Then apply a final thin coat of glue and set the cloth a final
John A. Tuttle
Brick, NJ, USA
[ Thanks, John, I'll place the photo at the MMD Tech site,
[ http://mmd.foxtail.com/Tech/ -- Robbie