Spark plug metal finish restoration

[Mike S]

 
  I was able to purchase a set of NOS '67 vintage (per the box date) of AC 43N Fire Ring plugs for a low cost because they had slight oxidation on the metal bases. Examining the base metal finish it appears to have been blued. I used EvapoRust
to soak the plugs in for 15 minutes then cleaned with a fine brass brush and rinsed. Then the metal was treated with Birchwood Casey gun blue liquid for 30 seconds to restore the finish. This actually works great and the plugs look new again. Comparing these 'restored' plugs to another NOS set I have that's in great condition, the finish darkness matches (almost black). 

[169INDY]

Great Tip with explanation and photos , Thanks for sharing.

JIM

[Petes L48]

I've tried re-bluing parts with limited success, using that same brand in the little blue plastic bottle. Yours look great. Did you remove all the old finish with the brass brush, or just touch up spots after removing the light rust? Also did you fully submerge the metal section of the plug?  Maybe I should go back and re-read their instructions.     Thanks

[Mike S]

Hi Pete,

   After letting the plug sit in fresh EvapoRust (just up to the top of the metal where the porcelain starts)  for 15 minutes and using the brass brush, most of the original finish came off.  These had light rust so 1 minutes worked fine. Then I rinsed it in warm soapy water to wash the EvapoRust off, dried, then applied the blue solution using a cotton ball. It turns dark blue within seconds. I let it sit for 30 then rinsed in cold water and dried.

[Petes L48]

Thanks, I was probably not washing off the Evaporust properly.  I also noted on the bottle that the treated metal has to have certain content/properties like chromium etc.