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Joined: Nov 2016
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Sidelock
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Sidelock
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Has anyone mixed there own caustic solution for bluing gun parts such as trigger guards, forearms, and etc. I found a recipe online that was a 2:1 ratio of lye to sodium nitrate (or ammonia nitrate) added to 1 gallon of distilled H2O. I was planning on using the sodium nitrate to avoid the ammonia gas. I have bought the chemicals to mix and found it would be a lot cheaper than purchasing premade salts. I was wondering if this would produce a finish similar to what brownells salts would? Thanks, Hereford
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Joined: Feb 2002
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Sidelock
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Sidelock
Joined: Feb 2002
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I used to use: 5# lye 4# Sodium Nitrate (you can use Ammonium Nitrate as well) 1 gallon of water (distilled)
Blues at 265/275F Nice blue/black finish very similar to Brownells salts Careful when mixing,,lot's of heat generated and the soln can 'boil' and splatter as it's being mixed. Eye/ full face/cover all skin. Even then it'll eat right through most cloth and even leather when hot.. Keep the kids .pets and nosey neighbors away.
It's not a spectator sport, there's no running away from the burns it can inflict in a matter of a split second should any part of your equipment topple especially when it's near 300F.
Clean up is no fun and the evaporating water from the process carries the salts with it and leaves a layer of them deposited on everthing in site. They then absorb water from the air and become 'wet'. Any encrusted steel will rust,,wood will become soggy. Needs good ventilation or done outside.
You can get away with very small bluing runs w/o too much mess but a large long tank will spew a lot of water and salts into the air and it'll build up quickly. For small parts like you mentioned, doing the bluing in a surplus 50cal ammo can works well. Remove the paint first of course. After the salts have cooled down when done you can simply put the cover back on and it's sealed back up for the next run. Unsealed, the 'tank' full of salts will absorb water from the air. Not a kitchen DIY project. It eats aluminum quickly. Have fun...!
Now I just rust blue!
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Sidelock
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Sidelock
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The traditional Birmingham bluing tank formula as used for decades.
3 Pound of Caustic Soda (Sodium Hydroxide) 5 Pound of Sodium Nitrate 3 ounces of Sodium Chloride 17 ounces of Trisodium Phosphate 10 pints (UK) Distilled Water. Bring to the boil to use. Put a mark on the inside of the tank when first filled and keep adding water to keep the same level as the boiling reduces the water content. This formula produces that fine Birmingham made gun deep bluish black colour, if the solution looses its strength just add a little Sodium Nitrate to bring it back up to strength. My personal experience of this bluing mixture is that it is not too sensitive to moderate temperature swings as long it is kept boiling.
***** Do not try to use this to blue vintage side by side shotgun barrels, the liquid temperature is higher than the soft solder melting point that hold's the barrels together and the ribs on. Rust bluing only for them!!!!
The only lessons in my life I truly did learn from where the ones I paid for!
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Sidelock
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Sidelock
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Damascus, It's not the heat that causes loose ribs, it's the caustic action. Same results though, not for double barrels. Mike
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Joined: Jan 2013
Posts: 1,124 Likes: 195
Sidelock
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Sidelock
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Der Ami I think you will find that Lead and Tin (the main constituents of soft solder given the Eutectic is lower than the melting point of each) are metals that will not react with Sodium Hydroxide. The reason it melts the solder is because the large quantities of Sodium nitrate and Sodium Hydroxide increase the temperature of the mixture in the tank above 145C the melting point of some soft solders. better safe than sorry!!!
The only lessons in my life I truly did learn from where the ones I paid for!
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Sidelock
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Sidelock
Joined: Jan 2002
Posts: 13,180 Likes: 1161 |
If I may interject a question into your, and Der Ami's, exchange .................. if you are watching the thermometer, and are sure the temperature doesn't exceed a particular point, how do ingredients in the mix cause the temperature to increase above that which is desirable? They certainly can't do that without the thermometer recording it.
?????????? SRH
May God bless America and those who defend her.
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Joined: Mar 2012
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Sidelock
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Sidelock
Joined: Mar 2012
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A simple mix that works well is, 225 oz sodium hydroxide 5 oz sodium nitrate 1 gallon de ionised water. (Clean rainwater is as good )
Get this to boil at 140-145 degrees C and it will give a very good deep black.
Usual warning time . This along with all hot salts is really nasty stuff, it'll blind you instantly, cause horrible burns and will erupt if you add water too quickly. If you take your time, take care and keep your eyes and skin covered, then it's no riskier than frying food in oil. Seriously, take care and don't get distracted. Fresh salts can be a bit hard on some trigger guards and levers, a lean mix at a slightly lower temp initially will avoid any problems , practice on some old parts or scrap bits of metal will help stabilise the mix . Keep parts in the top half of the molten salts, and take care when adding water. As was said above, definitely an outdoor job.
Last edited by Nick. C; 07/19/17 07:36 PM.
Rust never sleeps !
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Sidelock
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OP
Sidelock
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Thanks for all of the information and tips. It seems like there are many different ratios used and that they all yield a quality finish if the metal is prepared correctly. I have still not made or assembled the tank setup yet. I was initially going to use something like a pot to just blue small parts but am now thinking of just a standard 40in long tank so I can blue rifle barrels etc. Whenever I made my pipe burners for the rust bluing tanks I have I made a few extra for rinse tanks etc. and may have to do some work on them to increase the amount of heat they produce to raise the temp high enough. Thanks, Hereford
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Sidelock
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Sidelock
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Sometimes I do wonder if people read what you write then try to put their own changed interpretation on things causing me to doubt myself. Now why am I saying this?!! For a start in the bluing tank formula I posted I did say it is used at boiling point, now as this is a very old formula used possibly for a hundred years or more the instruction for use is very clear use at boiling point and keep the water volume the same as when first mixed. There is no mention of thermometer just use at boiling point! What surprises me is that in basic High School Physics there is an experiment that if you dissolve table salt (Sodium Chloride) in pure fresh water its boiling point temperature increases, now dissolving eight pounds plus of salts in ten pints of water will sure raise the boiling point considerably. Next Solder. This subject is possibly one of the least understood especially regarding the Lead Tin varieties. The common two varieties we come across are the 60% 40% Tin Lead or Lead Tin but that is just scratching the surface. Here in Brit land before WW2 there where many manufactures of industrial “Soft Solders” each with their own little adjustments to the basic formula i.e. The addition of small amounts of Copper, Bismuth, Aluminium to name just three, all to adjust the eutectic (the melting point of the alloy) giving a melting point span from about 78C Pewtalloy (Woods metal) to over 200C known as high temperature soft solder. Because the melting point span of differing makers soft solder could be so great unless you really do know the melting point of the solder used in their construction the instruction is “Do not put soft soldered double gun barrels in the tank.” Now finally Lead and Tin are two of the least reactive metals hence their use in roofing and the food canning also rust protection industries. Is it really me???
The only lessons in my life I truly did learn from where the ones I paid for!
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Joined: Jul 2012
Posts: 4,474 Likes: 208
Sidelock
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Sidelock
Joined: Jul 2012
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A common temp. for bluing solution is 265-285 degrees F. A common solder for ribs on doubles is 50/50, although 60/40 may also be found. The melting point for these solders is higher than 285 degrees. If temperature were the problem, you also couldn't blue rifles that have soldered on sight bases, sling swivels, etc. in caustic solutions. For accuracy sake, some new double and drilling barrels are blued in caustic solution; but only for a short time( less than 14 min.)specifically to remove solder residue that is difficult to see in the polishing process. Mike
Last edited by Der Ami; 07/20/17 11:08 AM.
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