Professional Jeweler Archive: Replacing Gaskets

August 2000

Timepieces/Education & Repair

Replacing Gaskets

This procedure adds value to your store’s watch service

– by David A. Christianson, President of the American Watchmakers-Clockmakers Institute
Certified Master Watchmaker

Deformed, cracked, stretched, brittle or broken gaskets must be replaced. This procedure is normally done by a professionally trained watchmaker. But if your store has access to gasket assortments, you can perform the procedure at the service counter.

Choosing the Correct Gasket

Brand-name cases, those with actual case numbers engraved inside or outside the case back (in addition to a serial number) require gaskets designed specifically for those cases. They’re available in assortments from each manufacturer or by special order. Select the branded case-back gaskets using the manufacturer’s conversion chart or the brand and case number. Ask for help from your watchmaker if you can’t read the gasket system chart.

Generic cases use generic gaskets. These gaskets are available from your supplier in assortments. Measure the diameters of the gasket and inside lip of the case back in millimeters. Use these measurements to find the correct gasket. You’ll know you have the correct one when you feel the gasket drag as you replace the back. Once you feel the drag, turn the case back another half turn; the back should be seated against the case with no gap.

Most quartz cases use O-ring gaskets. Some use flat ones. Be sure you replace flat gaskets with new flat ones that measure the same thickness and width as the original. Also be sure to lubricate the replacement gasket with silicon gasket sealant before installing.

Stem/Crown Gaskets

Stem/crown gaskets are O-rings found on the stem near the bottom of the crown or on the crown extension below the actual winding knob. They are measured the same way as case-back gaskets. Generic cases use generic replacements; branded cases use replacements from the manufacturer.

To remove the old gasket, pry it off with sharp tweezers or cut it off with a thin, sharp knife blade. Slide the new one on the end of the stem and gently work it up the stem and into place with your fingers. Lubricate the gasket before reinstalling the stem and crown assembly.

Hidden Crown Gaskets

To replace a hidden crown gasket, you have to replace the crown itself. This is best left to a watchmaker. You can tell whether the crown and its hidden gasket need replacement when the crown, installed in the watch case, turns easily without any drag between the crown and case tube.

David Christianson is fourth-generation owner of Christianson Jewelry, Kendallville, IN. In addition to serving as AWI president, he is a certified master watchmaker and a fellow of the British Horological Society. He discusses watch repair for the sales staff in this column each month. Send questions, suggestions and comments to Professional Jeweler, 1500 Walnut St., Suite 1200, Philadelphia, PA 19102;

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