Home DIY phosphate/ parkerizing process

[bigduke6]

For those who have seen the thread I posted regarding a restoration of a No5 (Jungle carbine ) Bayonet, I mentioned I would write up the process, I was contacted by a member just recently who had been pointed in my direction By Peter Laidler, the Milsurp member asked if I could help him with the finish on his bayonet, which I,m more than happy to do, and will proceed with his bayonet in the next few weeks, it was only when walking around Aldi today to get some supplies (Beer) I noticed the compressor equipment they have and thought no better time to post this.

First off I,m no expert on metal finishing its just what I,ve read and tried, this is just one example that has worked and the proof is in the pudding as they say and the bits are not hard to come by.

The beginning of the process is the spot blasting, this was done using one of the very cheap spot blasters from Aldi, they dont look much and are not built for commercial use, but for the one off jobs I cant fault them for the price etc they are around £9 and if you wait around till they go half price ( as much as a pint in London).

They come with a small amount of aluminium oxide, this is the medium for this spot blaster, I (or we when I was doing some brackets for my mates Barr and Stroud range finder) tried small grain sand but didn't have the same effect as the aluminium.





The blasting was done in a ships engine room workshop, due to space plus the oxide gets every where and I needed to reuse the oxide as its all I had with me.

Results are good, my mate was impressed, the finish does smooth out when phosphated, I dont know if its part of the process and its the acid attacking the blasted finish?



I must stress PPE (Personnel protective equipment) Gloves, goggles, apron etc, should be worn at all times this was done under extraction fans Chuckindenver says when using Phosphoric acid it should be done outside,

The hardest thing to obtain would be the phosphoric acid, I used metal brite which contains a 15 % solution, and used half a cup full, (they were the medium size paper cups)

The other ingredients are fine wire wool (a small hand full), 1 gallon (5 ltrs ) of distilled/de ironized water, manganese dioxide, this can obtained form a alkaline battery, ( the battery contains zinc also) and a large stainless steel kit or pan, a glass bowl will do also.

The contents of a D size battery will be plenty I used about half of the maganes ( the black stuff) this needs to broken down into a powder.




Fill up you pan or bowl with the water, and bring to boil, add the maganese and wire wool and phosphoric acid (metal brite in my case half a cup full),



and it will look something like this,



once the wire wool is dissolved, then add the part to be parkerized/ phosphate, there is a reaction here and noticeable, can be seen in here



approx 20 mins or when the reaction begins to ease, remove part, the part will have a white kind of residue on this can be cleaned off, I used kitchen towel to wipe it clear,



after the initial wipe, I wiped it over with AC90 (WD40) I did this a few times then let it dry.



The picture makes it look very black, but in certain light it is a very dark grey.






I did a SMLE action I,ve had for a while using the recipe , this was a sporterised SMLE, which I stripped for the action, it had been polished to high heaven and had more holes than a colander , so a spot blast and a pickle brought it back to a reasonable standard. this is a long term project that I hope to finish one day am looking to mount a scope mount/mounts and scope that fit the period. a before and after, (it still may end up as a De-Lisle which it was bought for)

Information

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[jmoore]

The hardest thing to obtain would be the phosphoric acid,

I've always purchased the acid from automotive paint supply stores. It's alsp a good place to get fine grade sandpaper- in the range of 1400-2000 grit if you have need of it!

[Chuckindenver]

you can get real manganese phosphate from a potery supply store.. steel wool isnt really needed.
a less harsh acid should be used. search the net...you can find it.
a table spoon of sodium hydroxide will cure the light and dark areas. that too much free acid. from a harsh mix.
NEVER cook it inside if you are using phosphorice acid, even with a window or door open..you chance a nasty lung infection by breathing the gasses..
use the same acid deluted, to pre strip the old finish, dont leave the parts in the acid more then 30 mins, wrinse and wash with a soap pad, wear rubber gloves when handling your parts, throught the proccess, it will avoid splotchy finishes.

[bigduke6]

Thanks Chuck, the pics show it being cooked on a ships galley stove, but had BIG extracters above, but I will update the post with your warning. This recipe was from the net, couldnt find anythig with a less harsh acid, the stuff i used containing the acid was metal brite think its similar to the stuff sold for cleaning aluminum wheels etc, we often use it neat for cleaning Purifier bowls, to remove the lime scale build up.

http://www.offshoresupply.co.uk/file...ons/ZUN002.pdf

[Chuckindenver]

as much as i like to DIY...its really easier to just buy a gallon of concentrate from a metal coatings supplier, they have them all over the world.
a gallon will last the average hobby gun guy a while,
many years ago, when very first started to do restorations...i played with the net storys mixes..with less then good results..
try and avoid using WD 40 for your curing oil...for lack of a better word..it sux.
ATF deluted with pinesol works best, you have to wrinse the work right after its out of the bath, to get the potasium off and nuturalize the acid.. or it will rust..oil and grease...and avoid using any paint thinner, mineral spirits ect..
phosphate has to have oil and grease or its a wast of time.
always use in a safe area, outside...i type this as a 8 quart pot of blue salts cools on my kitchen stove lol...do as i say, not as i do lol

---------- Post added at 06:57 PM ---------- Previous post was at 06:50 PM ----------

heres the top secret formula that all the commercial suppliers use...
25 gm phosphoric acid
1,5 gm manganese dioxide
1 lit water