Thread: DIY Home Parkerizing

So I have been needing to do some parkerizing for a while for a bunch of parts for my business. I sent the job out for quotes to 3 different places locally, and no one got back to me. Maybe I smell funny or something, I dunno. But their loss is my gain.

After doing a fair amount of reading online about what it takes, I decided to take the plunge and do it myself.

I started out with a trip to my local home depot, and after asking for "Jasco Prep and Prime" (what most home parkers use) I was directed to another product called "Klean strip Phosphoric Prep & Etch" which comes in a 1 gallon bottle for $14. It's an angry green color.

I setup my park tank, a 1-gallon camp enameled cooking pot and put it on top of my hotplate out in the back yard. At first I added about 60mL (yes, mL, I used a graduated cylinder) to 2L of water. And then added some Manganese Dioxide I took out of a new carbon-zinc (usually labeled "Heavy Duty") D cell. I added about half a tablespoon of the MnO2. I then set the hot plate to warm it up to 90C and waited for it to heat up. While parking the first batch of parts bubbling was going slow, so I added another 60mL of acid to the solution.

I parked a few parts, usually simply waiting until the parts came out the black color I was looking for, washed them in clean water, and then covered them in hoppes. Results were good.

For the second batch, I was a little sloppy with my measuring and added way more acid. The parts came out looking horrible.

So now I'm on the third batch, and the parts are looking great, deep black colors all around. I had the girlfriend take some pictures, which I'll upload a bit later. The final solution I came up with is this:

1 Tblspoon MnO2
130ml Phosphoric acid (the product mentioned earlier)
2L distilled water

Add about 1/2 of a muffin of degreased (with brake cleaner) steel wool when the solution is at temperature, once it dissolves it's time to start parking.

A few observations: The parts I'm working with are lasercuts, they have been stuck in the rotary tumbler and dehorned and deburred. They were sitting in water soluable oil to keep them from rusting while I waited to get the chemicals. When I pulled them out of the tray with the oil, I sprayed them down with purple power (a degreaser availible at autozone) and then rinsed in hot water. I then connected all the parts together with wires (they are small parts) and sprayed them down with brake cleaner. I would then hang them up for a few minutes to dry, make sure the water level was right in the tank, and then dip them. Bubbling is intense for the first few minutes and will then level off. I usually check the parts after about 10 minutes, and I will usually let them go for another 5-10 minutes checking periodically to see how the finish is coming out. Once they achieve the desired level of blackness I pull them out. If they sit until it stops bubbling (like most people say) they usually come out more of a gunmetal grey color, and not a deep charcoal black.

After you pull the parts out of the solution, wash them with clean water, and immediately spray them with oil. I highly recommend using a spray type oil, like rem oil, WD40, or something similar. Alternatively, you could have a dip tank. Since I have neither, and am using a hoppes soaked rag, it's kinda've a pain to get them all covered right away.

So that's it. I'll post some pics later.

Sounds like fun cant wait to see. Did you do before and after pics?

Sorry about the delay on posting some pics, as usual life has gotten in the way.

Putting the parts in the bath


Parts before parkerizing (hard to tell of the finish)


Still dripping solution (they look kinda've a gunmetal grey)


Here's what the bath looks like, kinda foamy


And now for what is probably the most important picture. The results!


As you can see the two wrenches in the middle havn't been parkerized, and the smudge on the third wrench is from the oil I was letting soak into it.

So I've been messing around with this process a bit more lately. and I've come up with some better results

First, the solution I'm using is 4oz of phosphoric acid to 1 gal water (regular tap water works great)
Add about 4 tablespoons of Manganese dioxide, available from pottery stores (I got 5 lbs for $4)

Bring the solution to 190F (just below boiling).

First, feed the solution half a muffin of a degreased steel wool. Allow this to dissolve, you will notice that odor change I talked about earlier, I finally figured it out, it smells a lot like coffee oil.

Then add your sandblasted parts. I've gotten in the habit of just putting all my parts onto a wire, sandblasting them on the wire (keeps them from falling through the cracks) and then blasting, and dipping. Allow the parts to sit in solution until they no longer bubble. Remove, dip in hot water, put them in an oil pan (just what I used) and hose them down with any lightweight oil, I think last time I used some used rotella T diesel oil. If you want that green patina, use cosmoline.

Also, the most important thing, after oiling, let the parts sit for a day or two before you pull them out and start cleaning them, this gives a chance for the reaction to finish, and becomes harder and darker, especially if you have oil with extra carbon in it (the used diesel oil). After curing, take the parts out, clean them off with a little simple green and a paper towel and hot water, then re-oil with some light machine oil, or last time I did it, I used some very thin floor sealer (thinned it out with paint thinner, so it was only slightly thicker than water). Now the parts will be black as coal, and fairly resistant to damage for a lifetime.

What is the concentration on your phosphoric?

4oz acid to 1 gallon... so 1 gallon is 128oz, so when diluted it will be 128:4 or 32:1 so about 3%. You don't want a high concentration of acid, because the acid will attack the steel rather than passivating it. I've done some where the acid solution was too strong, and it actually eats the steel and you can see the crystal structure of the steel, which is pretty cool, but not very useful as the parts come out really sharp.

Great write up! Thanks for the read!

one thing I would suggest is rising the parts in some water with some baking soda in it.....the soda being a base will help to neutralize the acid

good write upon the park solution mix though....I'll have to try mixing my own

We have a stainless creations tank, hot water heater element, and I'm currectly looking for a better thermostat.