Oh well I realized why the hell PM? No big secret here.
So here's the natak:
HOT CAUSTIC SALT BLUING
Please Note: The formula and procedure is NOT my original and I don't claim so either. It is freely available on the net and print. I've only condensed it down to Indian circumstances. It may not be ideal for every one or all circumstances but it has worked for me. In an earlier post I'd said 'simple' DIY processes, er...well they aren't all that simple...
... I meant somewhat simple enough for me
This process is supposedly the most common blue finish in the firearms industry. There are numerous minor variations and additives, but this is the essential core of the process.
Warning:You will be handling caustic and corrosive chemicals, fire...and a lot of heat. A circumstance that is not potentially dangerous but IS dangerous....particularly an angry wife. You will risk severe burn, both of chemical and incendiary nature from careless or improper usage.
I'm not to be held responsible for any accidents or ruined guns...don't blame IFG either
While my personal preference is 10 Day Rust Blue process because of its durability, it's too much of a pain in terms of time for most home Einsteins.
I'll describe, instead, the Hot Caustic Salt Bluing Process- Which usually can be done in half a day- from polishing, prepping/cleaning , bluing to oiling. You'll find that the polishing and cleaning aspect will take 90% of your time.
1.
Polishing: I'll brush past the polishing and cleaning aspect in interest of being terse. Needless to say the gun should be fully disassembled (Assuming you can and have some basic tools)... I'm also assuming you've stripped the nickel plating... Sand it down with #400 Silicon Carbide water proof Paper(Rs.10/-) if you'd like it to be lustrous. You'll probably not have a buffing wheel so just polish the gun with #400 to your hearts content. Don't over do it though.... particularly on bearing surfaces- you may ruin your gun.
2.
Cleaning: Soak a clean piece of cloth with nail polish remover or Carbon-tetra-chloride and use it in whatever method you can to wipe off as much oil and grease as possible.Have a clean tub full of hot water and use a toothbrush and vim or Pril to clean out as much of the remaining oil grease and muck as possible- Rinse the parts thoroughly with fresh hot water -
By the way - Leave out the barrel- No point bluing it as it will wear off pretty quick. Do not blue any springs either keep them stored away nicely oiled.
Also be careful with small parts like cross pins and screws- easy to send them down the sink when rinsing.
Remember: Degreasing thoroughly is of utmost importance- spend as much time as you can on it- Or else you'll end up with a ruined finish.
3.
Bluing
4.
Hot water rinsing
3.
Drying and Oiling
The formula is surprisingly simple:
1. Sodium Nitrate 1.8kgs
2. Sodium Hydroxide(Caustic Soda) 2.2Kgs
3. Distilled water 2 Gallons
Ok...Ok the Kg's part looks scary, well... I usually mix up the lot for long guns and my largish bluing tank. Some one good with math can work it down to percentages and you needn't mix so much for such a small job. But its important to have an adequate extra to 'concentrate' the solution in certain conditions. I usually store the excess solution (Properly sealed) for later use.
The chemicals can be bought off the shelf at any laboratory supply shop. They are usually available in 500g containers.
Prices:In my town as of 2008. May vary elsewhere.
Sodium Nitrate 500g- Rs.125
Sodium Hydroxide 500g- Rs.160
Distilled Water 1 bottle (beer size)- Rs.10
Work that out accordingly.
EQUIPMENT YOU'LL NEED
Ok NOW you'll need a sturdy Stainless Steel or Iron Pot- Just large enough to completely submerge all the parts. For the Ashani that wouldn't have to be too big.
IMPORTANT Don't even think of using an aluminium vessel- Sodium Hydroxide will dissolve it. Copper or brass pots are also known to be reactive.
IMPORTANT Either your wife should not know or simply buy a vessel for the purpose. I find a Medium sized Black iron karahi is ideal.
You'll also need a Gas stove- Sweet talk you wife into allowing you to take the LPG stove outside. Use the larger burner. Find some way of safely keeping the pot secure over the flame.
You'll need another pot with fresh hot water nearby for the post blue rinse.
A make-shift ladle , preferably made of steel - polished cleaned and degreased- This is to stir mixture.
A lab thermometer- I have one that reads to 250degreesC. Cost me Rs. 120
Thick clothes, shoes and eye and face protection of possible.
Now is also when the natak should move outdoors because you'll be dealing with fumes which aren't too nice to have within your respiratory system.
BTW there is a variation of the formula with Ammonium Nitrate instead of Sodium Nitrate and is supposed to be better- But I chose Sodium Nitrate since Ammonium Nitrate produces ammonia gas which has this awful stink- It is also a restricted compound in many places.
MIXING THE SOLUTION
NOTE: The mix described below is for the full amount- not a scaled down amount
(Like I said if some one can work it doen to percentages, you could mix smaller amounts)
1. Fill the container with 1 gallon of water - room temperature
2. Use a scale to measure 1.5-8 Kgs of Sodium Hydroxide - Don't get it on your skin - you'll not like it! Slowly add 1 cup at a time to the water and stir gently. Stir till each cup full is dissolved. The solution will heat up and give up fumes - don't breathe the fumes- its again not nice.
3. Place the solution in the burner and heat it till its warm
4. Take 1kg of the Sodium Nitrate and dissolve similarly one cup at a time- Stir gently
As the solution comes to a boil it the compounds will dissolve fully.
Add salt and pepper for taste.
.... kidding
There you go- Your Solution is mixed- You can either use it immediately or carefully transfer it to sealable containers when it has cooled down a bit. Scrape the residual crystals (Not with your bare hands!) and plop them into the storage as well.
If you're using it immediately:
The solution is supposed to be in a vigorous rolling boil now. Dip the thermometer and see that it doesn't go lower than 122degC or higher than 129degC- You'll get funny colors if you go higher or lower....either way your finish will be ruined and you'll have to reblue again at the right temperature range.
Suspend the parts in a clean degreased iron or steel wire. Oh ya...I forgot to mention - No touching any of the cleaned parts with your bare hands since fingers transfer grease and sweat...fingerprints....etc. use clean rubber gloves.
Small pins and screws can be placed in a small 'tray' bent up from non-galvanized steel mesh or even a stainless steel sieve(chagni) with the handle bent and hooked up.
Immerse all these into the solution taking care not to let them touch the hot bottom.
20-30 minutes is enough for most steels- provided they have been cleaned and degreased adequately. A plum color means they'll need to be longer in the solution. Take them out and see if the color is to your satisfaction - if not, simply dip it back in for a while longer. Note- hardened steel with high ally or carbon content will blue lesser than softer low carbon steels- A gun is invariably made up of many kinds of still. So you may need to adjust the immersion time of different parts accordingly. The differences in the Ashani, however, will not be major, so a common dunk should do for all parts.
If the solution starts to get too hot(eye the thermometer), you can reduce the temperature by adding water(Gently). Don’t try to control the temperature by cutting back on the gas burner.
Also remember not to fill the container upto the brim or you'll spill the boiling stuff all over... including yourself...you won't like that either.
Once you're done and satisfied with the results- Dunk all the parts into fresh boiling water for about 10 Minutes. You need to do this to kill the chemicals and dissolve/rinse all traces of the solution from ever nook and corner of the gun. If not, you'll find white crystals bleeding out of tiny corners and joints within a day or two- Not nice.
If you have the patience- rinse them in another lot of fresh hot water.
Once done- Dry them out thoroughly and 'saturate' all the parts with good gun oil or even WD40- If you have enough oil, leave them submerged in oil over night.
You should then wipe them down briskly with a clean lint free cloth. Then oil them as you would normally.
Reassemble
Done!
You should now have a properly blued gun.
As the reader would have noticed- The process is fairly messy and not something that is advisable for everyone or for keeping the peace at home and the neighborhood
Do it only if the drive to do so corresponds to your ability to spare time, a bit of money and of course, deal with a big mess.
This is not an authoritative treatise on bluing. Its just an exposition of the more general bluing methods in use. There are countless others which are just as good, if not better. Remember also that this particular bluing process will only be as good as the surface of the metal. It will look deep lustrous and mirror-like if you do a thorough job with the buffing and polishing before the dip. The finish will not cover up nicks and scratches.
Like I mentioned earlier, I prefer the 10Day Rust Blue, because you only have to deal with boiling water and a lot of steel wool or a wire wheel. The only catch is, the solution is a mixture of several chemicals in precise and minute amounts- Some of which are highly toxic (like Mercuric Chloride)
Browning is even simpler in composition but the finish belongs to antiques not present day firearms.
Nitre bluing is the simplest but the high temperatures will affect the heat treatment of the metal and so may not be too advisable. It is also dangerous because in this case you're dealing with molten compounds and not a solution.
Hope this has not been too round about.
Stay safe and when in doubt don't!!