As promised in the introduction section, here is my write-up for my parkerising formula.
I recently decided to try my hand at Parkerising as it would be a very use full technique to coat some of my home made tools and many other things I make in my workshop. I did a little research and some experimenting and found that the following works for me.
To make up a Parkerising liquid you will need manganese dioxide 6 heaped tablespoons, about 500ml of phosphoric acid (rust remover) and 2L clean boiled tap water (cooled down) and a small piece of steel wool.
You can buy manganese dioxide or go the cheap route and source enough from old torch batteries.
To get the manganese dioxide out of the battery you have to carefully cut the zinc casing open which forms the cathode of the battery, you only need the black crumbly stuff, avoid contact with the silver paste in the centre, it will give you a nasty burn as it is corrosive.
Mixing the ingredients in a large plastic bottle makes it a little safer as it will prevent the chemicals splashing all over the place.
Put the water in the bottle and add the manganese dioxide, add the acid last, you will see that the manganese dioxide does not dissolve in the liquid, it sinks to the bottom.
Before you start the Parkerising process the part you want to coat must be degreased and any rust removed. I sandblast them and just wipe the part off with a clean rag and some acetone.
Now you are ready to start the Parkerising process, pour the mixture in a stainless steel pot or pan of suitable size, obviously an old one that is not going to be used for cooking again, put a small piece of steel wool (about the size of a marble) in the mixture and bring it to boiling point. When it starts to boil put the part in the pot and make sure it is covered by the liquid, I prefer to turn it over about every 5 minutes. Normally 20 minutes is enough to give a nice even coating, obviously bigger parts will take longer. I allow the mixture to boil, this will cause some frothing of the liquid but it works for me as I already mentioned.
I must be honest in saying that my description of this process sound far more accurate than it really is or needs to be, I found that the mixture still worked well after adding just water to compensate for evaporation, it only takes a little longer to get a nice dark coating but the end product is still the same.
In the photos you can see that I sandblasted my mauser rifle parts before coating them, they came out really nice and then my tangential tool holders that was also coated.
I hope this is helpfull information, any feedback, comments or advice will be welcome, there is always room for improvement on my side.
I hope everything is clear enough, if not, just ask.