De-tarnishing

[Brassdad]

My son's 1920 COnn Beast is one real tarnished piece of brass. We've used Brasso to knock the scaley areas down, but have reached a limit of sorts.
When we got the Conn it was raw, after reading various posts, it seems that we should leave it raw.
With 22 years in the Marine Corps I know what happens to "polished" raw brass, and while it would build the boys character to have to deal with that, I'm not sure I could be that cruel (on purpose).
What should we do to get the Conn back to a mellow appearance that will not show every fingerprint, but eliminate the "rain pipe" appearance?

Thanks

[Chuck(G)]

I'm sure that I'm going to get a bunch of flack on this one, but it works.

Get a quart or so of muriatic acid from your local paint store (it's used to clean masonry). Dilute it about 20 to 1 with water in a plastic (not metal) bucket.

Take the horn outside, remove the valves and slides and using a big sponge (wear gloves and eye protection!), wipe the horn down and watch the tarnish disappear. Using the garden hose rinse and wipe down the horn until you're sure there's no remaining acid. Dry the horn thoroughly and you should be done. This may leave a slight reddish cast to the horn; you can polish it off or leave it as-is.

The whole affair shouldn't take more than a half-hour.

[Chuck(G)]

Better be careful with this stuff though. I did some work flushing brass instrument once with muriatic (hydrochloric) acid but didn’t know whether to add the water to the acid or add acid to the water. I’ve heard if you get this backwards it may explode acid all over the place. Does anyone know which to do? I think you add the acid to the water (slowly).

I wonder also.... would this help me with my silver York stripping problem?

Always, always, always dribble the acid into the water while stirring. If you do it the other way, the heat of hydration may cause the water to boil, spattering acid all over the place! But I'd assume that the directions on the jug of acid would say as much in Big Bold Letters. Mix the stuff out-of-doors; the HCl fumes can really get to you.

I don't know if it would do much to whatever it is that's covering the silverplate on your tuba, though. Have you tried oven cleaner? Hot alkalai will sometimes soften very stubborn coatings.

[Dan Schultz]

Better be careful with this stuff though. I did some work flushing brass instrument once with muriatic (hydrochloric)

Muriatic acid deserves as much respect as any other chemical but it IS NOT hydrochloric acid This stuff has been used in radiator shops for years and was also very common in brass instrument repair shops. I use it to balance my swimming pool PH for pete's sakes. Keep it away from chrome plating but diluted as Chuck describes is fairly safe to handle. Straight from the jug the worst it's going to do is turn your skin a little yellow. There's another acid that will do the trick that's a little safer to use. It's called sulfamic (NOT sulfuric). It comes in crystal form and will not go into solution in water more that 20% by weight. This stuff is used to strip away the lime from the surface of exposed agregate sidewalks.

If you wanna try something REALLY safe... go to the grocery and purchase a half dozen bottles of cheap ketchup. There's just the right amount of acid in the stuff to remove the tarnish on brass. Problem is that you're gonna smell like a Big Mac for several weeks

[Ames0325]

Muriatic acid deserves as much respect as any other chemical but it IS NOT hydrochloric acid

Hate to contradict you but http://www.google.com/search?hl=en&q=muriatic+acid

The chemical substance hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. It is a strong acid, the major component of stomach acid and of wide industrial use. As a highly corrosive liquid, hydrochloric acid should be handled only with appropriate safety precautions.

Hydrochloric acid, or muriatic acid by its historical but still occasionally used name, has been an important and frequently used chemical from early history, and was discovered by the alchemist Jabir ibn Hayyan around 800. It was used throughout the Middle Ages by alchemists in the quest for the philosopher's stone, and later by several European scientists including Glauber, Priestley, and Davy, to help establish modern chemical knowledge.

During the Industrial Revolution, it became an important industrial chemical for many applications, including the large scale production of organic compounds such as vinyl chloride for PVC plastic and MDI/TDI for polyurethane and smaller scale applications, such as production of gelatin and other ingredients in food, and leather processing. Currently, production is approximately 20 million metric tonnes annually (20 Mt/year) of HCl gas.

[Doug@GT]

Better be careful with this stuff though. I did some work flushing brass instrument once with muriatic (hydrochloric) acid but didn’t know whether to add the water to the acid or add acid to the water. I’ve heard if you get this backwards it may explode acid all over the place. Does anyone know which to do? I think you add the acid to the water (slowly).

I wonder also.... would this help me with my silver York stripping problem?

Always, always, always dribble the acid into the water while stirring. If you do it the other way, the heat of hydration may cause the water to boil, spattering acid all over the place! But I'd assume that the directions on the jug of acid would say as much in Big Bold Letters. Mix the stuff out-of-doors; the HCl fumes can really get to you.

I don't know if it would do much to whatever it is that's covering the silverplate on your tuba, though. Have you tried oven cleaner? Hot alkalai will sometimes soften very stubborn coatings.

Do what you outtah...

Add acid to wattah.

[Dan Schultz]

Muriatic acid deserves as much respect as any other chemical but it IS NOT hydrochloric acid

Hate to contradict you but http://www.google.com/search?hl=en&q=muriatic+acid

The chemical substance hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. It is a strong acid, the major component of stomach acid and of wide industrial use. As a highly corrosive liquid, hydrochloric acid should be handled only with appropriate safety precautions.

Hydrochloric acid, or muriatic acid by its historical but still occasionally used name, has been an important and frequently used chemical from early history, and was discovered by the alchemist Jabir ibn Hayyan around 800. It was used throughout the Middle Ages by alchemists in the quest for the philosopher's stone, and later by several European scientists including Glauber, Priestley, and Davy, to help establish modern chemical knowledge.

During the Industrial Revolution, it became an important industrial chemical for many applications, including the large scale production of organic compounds such as vinyl chloride for PVC plastic and MDI/TDI for polyurethane and smaller scale applications, such as production of gelatin and other ingredients in food, and leather processing. Currently, production is approximately 20 million metric tonnes annually (20 Mt/year) of HCl gas.

Hmmm... a chemist I ain't.... I always thought hydrochloric was stronger that muriatic The stuff that I've seen in hardware and pool stores has always been sold as 'muriatic'... not hydrochloric acid.

Ketchup is safest Honest.

[Chuck(G)]

Muriatic acid deserves as much respect as any other chemical but it IS NOT hydrochloric acid

Okay, I'll bite. If muriatic acid isn't hydrochloric acid, what is it?

The chemical substance hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. It is a strong acid, the major component of stomach acid and of wide industrial use. As a highly corrosive liquid, hydrochloric acid should be handled only with appropriate safety precautions.

Hydrochloric acid, or muriatic acid by its historical but still occasionally used name, has been an important and frequently-used chemical from early history, and was discovered by the alchemist Jabir ibn Hayyan around 800. It was used throughout the Middle Ages by alchemists in the quest for the philosopher's stone, and later by several European scientists including Glauber, Priestley, and Davy, to help establish modern chemical knowledge.

Mayhap you were thinking of vitriolic acid? Aqua fortis?

One reason I don't like sulfamic acid for cleaning is that it's basically a solid in aqueous solution. That means that iresidues can crystallize after drying and raise Cain later. Muriatic is a solution of a gas in water; no crystals and when it evaporates, it's gone.

[Brassdad]

Sounds like I got a water project to do.

Any experience on what this will do to my driveway?
Will the neighborhood association be bringing a lawsuit?

[Rick F]

Any experience on what this will do to my driveway?

If it's a concrete drive, it will probably remove any stains, if it's a black-top drive, may remove driveway,

Seriously, about 19 years ago I used HCI to clean off my concrete side walk where a neighbor was having a swimming pool installed and dirty water from a excavating pump (contained lots of iron) was flowing over my sidewalk. This water flowed for 6 months so my side walk turned dark brown. I puchased HCI and it cleaned the sidewalk fine. The broom I was using to scrub was history as the bristles were eaten away. The last time I went to the chemical store to get HCI, I was told it's no longer sold to the public, but that I could buy Muriatic acid which was a little weaker solution. The label said 50% HCI.

[Chuck(G)]

Sounds like I got a water project to do.

Any experience on what this will do to my driveway?
Will the neighborhood association be bringing a lawsuit?

Rinse your driveway and it'll be fine. Keep the stuff off of the grass, though. Lime will work fine as a neutralizer, if you're concerned about the acid content.

[Dean E]

. . . . There's another acid that will do the trick that's a little safer to use. It's called sulfamic (NOT sulfuric). It comes in crystal form and will not go into solution in water more that 20% by weight. This stuff is used to strip away the lime from the surface of exposed agregate sidewalks. . . .

I also would recommend sulfamic acid, which is an ingredient in "CLR," from the hardware store. Most recently, I did a de-crudding operation on a Sousa outside in a child's $10, plastic wading pool.

[Dan Schultz]

Sounds like I got a water project to do.

Any experience on what this will do to my driveway?
Will the neighborhood association be bringing a lawsuit?

If you are using hydrochloric/muriatic/sulfamic acids, you will etch (damage) your driveway if it's concrete. It's probably not a problem if you have asphalt or if you use ketchup instead of acid.

Better check with your attorney before going ahead

[Chuck(G)]

If all of this acid talk has you a little nervous, try vinegar. It works, I've used it, but it smells. Safeway sells it for a little over a buck a gallon. But remember, it is an acid and should be rinsed thoroughly.

If you're looking at thick black crud on an old horn, vinegar won't make a dent in it (believe me, I've tried!). Muriatic seems to cut through stuff that even sulfamic won't--and it's fast and doesn't leave an odor behind.

Instead of ketchup, try this stuff:



contains hydrochloric acid.

[SplatterTone]

And then you got your toilet bowl cleaners many of which contain HCl. The gel type works well for cleaning the crud out of window air conditioner coils. I haven't tried it on brass wind instruments. The catsup is kind of slow, but it works.

[Rick Denney]

And then you got your toilet bowl cleaners many of which contain HCl.

Not all of them. One I just used last night (for cleaning in the bathroom, of course) used phosphoric acid.

Rick "who thinks it did no better than the rest at removing rust stains embedded into grout" Denney

[Chuck(G)]

the original question involved brass, but will all this acid/ketchup clean the tarnish off silver as well?

Don't know about sulfamic, but muriatic will clean tarnish off silver, but leave a cloudy residue that will need to be polished off. The reaction product, silver chloride, is very insoluble in water and serves to protect metallic silver underneath.

I suspect that sulfamic will also work, as I believe it's the active ingredient in TarnX.

[Chuck(G)]

Rick "who thinks it did no better than the rest at removing rust stains embedded into grout" Denney

Rick, have you tried oxalic acid or sodium bisulfite on that grout? Either should work fairly well.

[Kevin Hendrick]

The last time I went to the chemical store to get HCI, I was told it's no longer sold to the public, but that I could buy Muriatic acid which was a little weaker solution. The label said 50% HCI.

So, it sounds like "hydrochloric" is "all (or mostly) acid", and "muriatic" is only "half acid" ...

[Chuck(G)]

The last time I went to the chemical store to get HCI, I was told it's no longer sold to the public, but that I could buy Muriatic acid which was a little weaker solution. The label said 50% HCI.

So, it sounds like "hydrochloric" is "all (or mostly) acid", and "muriatic" is only "half acid" ...

If I went to a chemical supply house and ordered HCl, I would expect to receive a cylinder of hydrogen chloride gas. If I wanted the acid solution of HCl in water, I would specify "hydrochloric acid' and either the molar or mass concentration.

AFAIK, "muriatic acid" refers to any solution of HCl gas in water. What's sold as "concentrated" hydrochloric acid is about 12.4 M, or about 38% HCl by weight. Hardware-store muriatic acid is about 28% HCl by weight or about 9 M, so it's not that dilute.

Of the common strong (meaning nearly-complete dissociation, not corrosiveness) inorganic acids, HCl is by far the least hazardous (this doesn't mean that you can be stupid, just that the acid's quite stable and generally, reaction products are relatively benign). Hydrochloric acid concentrations above 10% do tend to fume (i.e. give off gaseous HCl), which is why I recommended doing the mixing out-of-doors.

One of the classic freshman-chemistry experiment is to place a beaker of hydrochloric acid next to a beaker of ammonium hydroxide. Before long, a "cloud" of ammonium chloride (sal ammoniac) forms from the products of outgassing of both solutions.
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