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Advice needed. Cleaning old bronze castings.


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Hey fellas,

 

I'm refurbishing some 120 year old steam car parts, oilers, valves etc which are bronze and some are heavily oxidized. I looked around on the web and there seems to be no real consensus on how to clean these parts. I can sandblast them, but the problem with that is they look brand new with no patina at all and it takes years for them to brown up again.

 

Any tricks of the trade anyone care to share?

 

Thanks, Ron

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 From google,

Bronze, brass and copper cleaner
  1. Step 1: Mix 2/3 cup vinegar and 2/3 cup flour in a glass bowl.
  2. Step 2: Add 1/2 cup salt and stir.
  3. Step 3: Spread on tarnished metal. Wait 1 to 2 hours.
  4. Step 4: Rinse, dry and polish with a soft cloth and a dab of olive oil.

How To: Clean Bronze

Restore the deep, beautiful glow to bronze jewelry and home accents with these safe, chemical-free techniques—and learn how to keep it looking great.

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How to Clean Bronze

Photo: istockphoto.com

Durable and resistant to water corrosion, bronze has a lovely, warm glow shown off to perfection when crafted into jewelry and such household décor accents as cabinet hardware, vases, and candlesticks. Over time, however, bronze tends to take on a greenish patina—not a surprising development when you learn that bronze is an alloy typically composed of 88 percent copper and 12 percent tin.

While some people appreciate the patina—it does impart an air of great age, even if it’s actually a fairly new piece—most prefer to restore bronze to its original glow. Luckily, you don’t need smelly or potentially caustic chemicals to clean bronze and polish the metal; in fact, you can easily get the job done with just a few household ingredients. Here are two easy and effective methods for how to clean bronze.

METHOD 1: CLEANING BRONZE WITH LEMON 

This first option is fast-working but requires ample elbow grease.

MATERIALS AND TOOLS Available on Amazon
 Soft rags
 Small bowl
 Baking soda
 Lemon juice
 Rubber gloves
 Toothbrush (optional)
 Olive oil

STEP 1
First, rinse your bronze jewelry or décor in warm water to remove dust. Wipe the metal dry with a soft, clean towel or rag.

STEP 2
Pour two tablespoons of baking soda into a small bowl.

STEP 3
Drip lemon juice—either fresh or concentrate—very slowly over the baking soda until the mixture is just wet enough to create a paste similar in consistency to toothpaste. You might see a little bubbling or some fizzing for a minute or two; this is normal.

STEP 4
Protect your hands with lightweight household work gloves, and then smear the cleaning paste over your bronze piece, using your fingers if the piece is small or a rag if it is large. If the piece has many nooks and crannies or ornate trim, use an old toothbrush to work the paste into the crevices.

STEP 5
With a polishing cloth, soft rag, or scrap of an old T-shirt, work the paste into the metal with small, circular motions. Focus on any especially heavy areas of patina. Continue to rub until you don’t see any more obvious spots.

STEP 6
Let the paste dwell on the bronze for half an hour.

STEP 7
Rinse the bronze thoroughly under warm water, rubbing with your fingers to remove all of the paste.

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STEP 8
Gently dry your bronze with a second soft cloth. If patina still remains, repeat the above steps.

STEP 9
Apply two or three drops of olive oil to your rag and gently burnish the clean bronze to bring out its muted shine.

 

How to Clean Bronze

Photo: istockphoto.com

METHOD 2: CLEANING BRONZE WITH SALT

This plan takes a bit longer, but you won’t have to rub as hard.

MATERIALS AND TOOLS Available on Amazon
 Soft rags
 Small bowl
– Table salt
– White flour
– White vinegar
 Rubber gloves
 Olive oil

STEP 1
Rinse your bronze jewelry or décor under warm water to remove dust, and then dry the piece with a clean, soft rag.

STEP 2
In a small bowl, combine two tablespoons of table salt and two tablespoons of white flour.

STEP 3
Slowly drip white vinegar into the bowl, mixing until the cleaner has the consistency of thick paste.

STEP 4 
Protect your hands with thin rubber work gloves and use your fingers or a clean rag to rub the paste onto the bronze. Rub in small circles to work the paste over the entire surface of the metal, including any crevices.

STEP 5
Let the paste remain on the bronze for an hour or more.

STEP 6
Use warm water to rinse away the paste, rubbing gently to remove any residue.

STEP 7
Dry the bronze with a soft, clean rag.

STEP 8
Apply one or two drops of olive oil to the rag, and then burnish the metal to bring out its shine.

 

Keep Your Bronze Looking Its Best

After you’ve followed either set of steps for how to clean bronze, you can maintain its shine following these tips:

• Regularly dust bronze statues and décor. If the dust is thick, rinse the piece in warm water to remove it, and then dry the metal thoroughly with a soft cloth.

• Store your bronze jewelry, coins, and valuables that aren’t on display in airtight plastic bags to reduce exposure to oxygen. It’s this process of oxidation that creates patina.

• Apply moisturizer, sunscreen, makeup, and other skincare products before putting on bronze jewelry.

• Rub your bronze jewelry with a soft cloth after each wear to remove body oils.

• Never wear your bronze jewelry into a swimming pool, as the chlorine wears at the metal.

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 This article, too long to post here, shows how to clean bronze and how to restore the patina if you clean it too much.

 It uses different products to give different hues to the metal.

https://deployant.com/the-bronzed-patina-the-curious-case-of-patina-how-to-get-it-and-how-not-to/

 

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I experimented a bit and most of my aluminum or bronze castings I ended up sandblasting which left a flat sheen that would pick up dirt from every source, even the slightest touch.  I then filled my blast cabinet with steel shot and blasted all the bronze and aluminum parts.  It seemed to recreate that "as-cast" surface finish, closed up the pores and had a nice satin sheen but also gave a little gray back into the color. Then clear coated with Eastwood Diamond Clear Satin.   After 4 years, it's held up well. Picture of the engine below is after 2 years.  I steel shot blasted the carb (after plugging all the holes) and you can see the results close up - maybe too clean for you needs.  I have also had good luck with an ultrasonic cleaner but it's only so big (clutch housing from my LaSalle - had to flip it once).

Scott

20180516_114736.thumb.jpg.fcbcad9f3eb43a00d09871231254cd55.jpgDSC06924.thumb.JPG.efb3a03f37d549f1dc1cb0dd12b1cb56.JPG20190209_154315.thumb.jpg.6df56a179fe569797e2ddd5efff21a88.jpg

 

Edited by Stude Light (see edit history)
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Thanks for the input everyone. The steel shot looks like a good process. I went with the easiest route for me right now and that was:

 

1 part flour

1 part salt

pour in vinegar until its a thick paste.

 

These parts were very badly oxidized with 120 years of build up. The long bronze piece had a thick green crusty coat. The smaller part was blackened with oil and heavily oxidized. I applied the paste all over the surface and let it sit for about an hour, then I started working it with a fine brass brush, which resulted in a good scrubbing, rinsing it all off and then doing a second application. It worked rather well, one benefit is the surface is left undisturbed, the stamped letters on the fittings which were faint to begin with look as good as new, sand or shot blasting would have likely distorted them.

 

Thanks, Ron

bronze.jpg

bronze1.jpg

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