Old Plug Washers Never Die…


New spark plugs always come with new washers—but if you’re like most people, you can easily get over five hundred hours of use out of aviation plugs. If you’re using automotive plugs, you still have these washers under the adapters that screw into the cylinders. The bottom line is that you will pull these at least once a year at the condition inspection, and once they have been torqued, they don’t have the same resiliency as they did the first time. That is, unless you anneal them. It’s an easy process: String a bunch of them on a piece of safety wire, and hang it from your vise handle or something else that will tolerate elevated temperatures. Light up your torch (a propane torch is fine for this), and heat them until they get nice and red. Then let them air cool. Voil—they are now soft and will torque just fine the next time you use them. Clean them up in the blast cabinet if you like them pretty, but it’s not necessary.

I have been reusing plug washers for years and always get a nice smooth torque when they are annealed. In fact, about the only time I don’t reuse them is when they get away and roll under the workbench with the spiders. I figure the spiders can have them.

This little wire holder is nothing more than heavy stainless wire with a crook bent in each end. Take what you need, re-hook them, and keep the rest for the future. If you keep them on your spark plug tray, you should always have annealed washers handy when reinstalling plugs.


  1. Anneal copper washers by dropping them while red hot into a can of cold water. Letting them cool in the air keeps them tempered and much harder than they should be.
    Just consider how the copper washers cool when installed under the spark plug… And the need to ‘soften’ them before reuse.


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