Klarinet Archive - Posting 000313.txt from 2010/08

From: K S <krsmav@-----.com>
Subj: [kl] Cigarette Papers -- Checking for Pad Seal
Date: Sun, 22 Aug 2010 20:35:42 -0400

Jennifer -

You ask: "How does a strip of paper help to check for pad seal? Is
this better than sucking or blowing into the sealed joint to look for
air leaks? What purpose does the match stick serve?."

A pad must seat with the same pressure all around the rim. Sucking or
blowing detects only major leaks and doesn't show where around the rim
a leak is. I think 100% of repair technicians check pad seating by
inserting a slip of cigarette paper between the pad and the rim,
pressing the pad down lightly and sliding the paper out. Then they
move the paper about 30 degrees around the pad and repeat the test,
and so on all the way around. You want to get the same sliding
resistance everywhere. If the pressure is uneven, you hold the pad
cup upside down over the flame on your alcohol lamp or Bunsen burner
to melt the shellac under pad and reposition the pad.

Attaching the slip of paper to a matchstick keeps your fingers away
from the flame and makes it easier to hold. I think about one
technician in five does this. The rest just pinch and hold the paper.

Ken Shaw
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