Parkerizing Small Parts & Fasteners

I finally got my frame sand blasted, primed, and painted. It just looked so pretty and black that I couldn't bring myself to cover it will silver and gold zinc coated bolts & nuts. I found a solution after hours of googling, parkerizing. I'm sure a lot of you are familiar with this process already, but thought I'd share for those who might not be. According to wikipedia, parkerizing is "Parkerizing, bonderizing, phosphating, or phosphatizing is a method of protecting a steel surface from corrosion and increasing its resistance to wear through the application of a chemical phosphate conversion coating." I list the steps below, but it was very easy and I was very happy with the results. The only negative I have so far is that the coating came off the points of my U-bolt nuts. This is probably from me having to run them up and down twice (forgot the washers the first time) using an air ratchet. I was able to do all these parts using only about $20 of solution.

Here are the basics:

1. Dip all the zinc coated fasteners into a 1:1 solution of Strip Kleen muriatic acid and water. I wore a full face mask and heavy rubber gloves, this stuff is nasty and not to be messed with. It took about 15 minutes for all the coating to completely come off the bolts. Once the zinc was gone, I dipped the parts in a water & baking soda solution to neutralize the acid, then rinsed under water for a couple minutes.

2. Mixed the parkerizing solution up in a stainless steel pot and heated it up to 190-200 degrees F using a hot plate in my garage.

3. Acquired a stainless steel vegetable steamer (no, not my wifes) put all the parts in the steamer and lowered it into the hot solution.

4. After about 10 minutes (the directions say once the bubbles stop), pulled the parks out and blasted them with WD-40.

5. Wiped clean and they were ready to be installed. The color is a dull black and I think will look great when it ages and gets some dirt on it.

 

I like the looks of it. I wonder how well they will hold up to corrosion?

 

Where did you find the instructions? According to Wikipedia, the solution is an ionic soup with some kind of metal - zinc or manganese - as a phosphate of some kind. This sounds like something gunsmiths would be familiar with. Did you use a product for the solution?

 

Came across this a while back when I was looking to do bolts and stuff on my Hurst. Haven't tried it yet, waiting for winter to leave and warmer weather-http://home.comcast.net/~rt66tbird/website/phosphate_etching.html

 

huh, very interesting.. I like the look when finished..

 

I got the solution from Palmetto Enterprises http://www.palmettoenterprises.net/Palmetto_Enterprises/-Welcome-.html. It is a mom and pop operation that sells the solution on the side. Super fast shipping and very helpful. I had to send him a money order, which I was leery of at first, but turned out fine. The instructions came with the solution. You have to have a stainless, glass, or plastic container to parkerize the parts in. The process doesn't work on stainless. I bought a stainless steel pot from a dollar store, along with some stainless tongs, total of $15.

 

The coating is porous and absorbs the WD-40 in the final step, this is what gives it corrosion resistance.

 

I parked most of the bolts, nuts, brackets for my Harley. Decently corrosion resistant when one applies some kind of oil. WD-40 is not a good choice for a rust preventive product. I used Brownell's solution. Prep is most important step.

Also keep in mind that like any acid treatment alloy steels are susceptable to hydrogen embrittlement. The longer your metal is in the solution the more hydrogen will migrate into the metal. So dunk only as long as instructions say, and for critical components follow up immediately (that means RIGHT NOW) by baking in an oven to drive out the hydrogen. Not sure what temps and times are required but the interweb knows all. I'd guess no higher than 250 degrees, maybe an hour. Higher and longer might temper back heat treated components. Do not parkerize spring steel.

 

The parts will rust if you dont regularly oil them especially if exposed to high humidity or water.

 

what about fluid film to prevent rust? lanolin based, migrates to spots you cant spray...