Parkerizing Mixture Ratio/Quantities, any idea?

[old1955]

G'day,
I'm unable to obtain pre made parkerizing mixture, so I have to make it myself

Has any one got any idea of the ratios/quantities to mix up a batch
of parkerizing brew ?

Manganese Dioxide + Phosphoric Acid + Distilled Water

The Manganese Dioxide I got from a ceramic supply place
Phosphoric Acid, I had to get from a chemical company
Distilled water, I just put a plastic bucket out in the rain, that gets it.

Thanks
Pete

[FlatHeadSix]

Pete
There is a little more to it than just mixing the chemicals together. The trick is to get the free acid ratio correct so you don't destroy your parts due to hydrogen embrittlement. If you get violent fizzing when you immerse the parts and they dissolve like an Alka-Seltzer tablet it indicates that the solution needs to be adjusted. Keep the temperature just under a boil and continuously agitate either the solution, the parts, or both to keep the bubbles off of the surface of the parts.

Always thoroughly degrease the parts before you parkerize them, even if they just came out of your blasting cabinet and look sparkling and brand new. I always boil the parts in a degreasing solution which removes all traces of oil and grease as well as releasing any glass beads which may be stuck in the pores. Rinse the parts thoroughly after degreasing and immediatley place them in the parkerizing bath. If you expose the parts to the air too long (and it doesn't take long) between the degreasiing, rinsing and parkerizing steps they will instantly rust up and you will have to start all over.

This recipe will make about 10 gallons of solution, you can adjust the ratios for smaller batches.

I use a mixture of 1/2 gallon technical grade Phosphoric acid to 8 ounces manganese dioxide . The Phosphoric acid is mixed with 9 gallons water in a stainless trough and brought to a rolling boil. The Manganese Dioxide is then slowly mixed in the solution and boiled for 10 minutes. When the parts are ready to parkerize after blasting with coarse ground glass I reheat the solution to 190 degrees F and immerse the part in the solution until foaming stops.

Then I remove the part from the solution, rinse with cold water, oil with a mixture of 1 gallon WD40 and 1 quart chainsaw oil, dry and re-oil.

Good Luck!, let us know how it turns out.

mike

[FlatHeadSix]

Oh, I almost forgot to give you the Safety Briefing! Be Careful and wear some protective gear like an apron, rubber gloves and safety goggles.

And I hope you remembered the mixing instructions for acid solutions from your high school chemistry class:
ALWAYS add the acid to the water, NEVER the other way around, or it will splash right back in your face.

ok, I feel better now

mike

[old1955]

G'day Flatheadsix,
Thanks for the tips and the safety ones too.
10 gallons at a time, are you parkerizing doors for cars before you paint them
or something.

You must have a mighty stove to heat all that up!
They say parkerizing is a great base for paint. I thought of doing some gas tanks
before painting them.

thanks again
Pete

[FlatHeadSix]

Pete
phosphate coatings work very well as a "primer" under paint, they provide excellent adhesion as well as extra protection for the iron or steel.

You don't have to use the whole ten gallons once you get it mixed up. After it cools down you can store it in one gallon plastic jugs, make sure they have caps which seal tightly. Once you start using any of the solution and it is exposed to iron and other metallic contamination do not return it to a container with unused mixture, the iron oxides will deteriorate the solution over time and render it useless. Continue to use each batch until it is depleted and then discard it, don't try to refresh it by adding additional chemicals or fresh solution, you'll never get the ratio correct. If the solution is still working all you need to do is continue to replace the liquid which boils or evaporates away with fresh distilled (rain) water. Mark the original level in your tank and keep topping it off with the water.

My big tank is only for gun barrels and other long items, I don't usually use it for the small motorcycle parts.

mike

[old1955]

Flatheadsix,

On a slightly different tack, you mentioned hydrogen embrittlement from parkerizing. I have know about that for
years but only in relation to chrome plating, I thought (assumed) that was a combination of the
electrical charge running through the metal and maybe some chemical factors that embrittled the metal.
But you say it happens with parkerizing too. So is it a chemical thing? Oh, it must be a gas thing I guess? I just twig to that.
I never thought of hydrogen embrittlement with parkerizing. But its hard to think a gas could invade a metal at any stage.

This is bringing out the chemist in the early Harley riders, careful.

Pete