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 was defective.
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: http://www.player-care.com/recovering_bellows.html
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 time.
John A. Tuttle
Brick, NJ, USA
08 Mar 2004 17:58:42 -0500