Over 20 years ago I pulled my first set of platinum spark plugs out of a car because the engine was missing badly. Two of the six plugs each had one whisker in the gap between electrodes. One crossed the gap and one was most of the way across. They started on the platinum center electrode and grew to the Inconel side (ground) electrode. They looked like straight, fine threads.

As I had worked in metallurgical R&D most of my life, I assumed they were whiskers, odd but no big deal, threw them away and put in new regular plugs. I was retired or I could have had a much better story with XRD and electron microscope data.

The reason I ask is that today I looked up metal whiskers in Wikipedia and found mostly info on whiskers formed on various solders and nothing on platinum.

  • 2
    $\begingroup$ Just curious, are those spark plugs made of pure platinum or is it a coating? $\endgroup$
    – ACR
    Commented Jun 8, 2020 at 4:50
  • 1
    $\begingroup$ A "pure" platinum spark plug would obviously be too costly. It seems that a platinum disc is used on the plug tips instead of a plating. $\endgroup$
    – MaxW
    Commented Jun 8, 2020 at 8:05
  • $\begingroup$ Platinum isn´t really expensive. Iridium is! :-)) The price differences for spark plugs are amazing, anything from two to fourty euros apiece. $\endgroup$
    – Karl
    Commented Jun 8, 2020 at 8:13
  • $\begingroup$ Whiskers growing on platinum are different to "platinum whiskers". The problem in you old spark plugs could be made of something entirely different. $\endgroup$
    – matt_black
    Commented Jun 8, 2020 at 16:09
  • $\begingroup$ Only the center electrode is Pt, Roughly 0.025" diameter , less than 2" long. Some have a few % alloy like iridium. I have replaced 2 sets of 8 since then and they looked like new after 100,000 miles. $\endgroup$ Commented Jun 9, 2020 at 18:28


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