Tool to remove encrusted soil from bronze

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Caduceus
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Tool to remove encrusted soil from bronze

Post by Caduceus » Tue Feb 25, 2020 1:48 am

I have a bronze object that's about 80 years old that has lots of encrusted soil on it. I can't use water to wash it for fear of corrosion. So I've been gently picking off the soil with a small plastic pick. Is there a better way to do this that won't take half my life or I am basically screwed? 8-)

123
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Re: Tool to remove encrusted soil from bronze

Post by 123 » Tue Feb 25, 2020 1:56 am

Caduceus wrote:
Tue Feb 25, 2020 1:48 am
...I can't use water to wash it for fear of corrosion...
If you don't use something like distilled water for cleaning/rinsing it would seem to be very difficult to ensure that any residual corrosive chemicals that might remain on the surface are removed. Depending on the item's size maybe it could be dried quickly with a hair dryer or placing it in front of a fan.
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Caduceus
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Re: Tool to remove encrusted soil from bronze

Post by Caduceus » Tue Feb 25, 2020 3:28 am

123 wrote:
Tue Feb 25, 2020 1:56 am
Caduceus wrote:
Tue Feb 25, 2020 1:48 am
...I can't use water to wash it for fear of corrosion...
If you don't use something like distilled water for cleaning/rinsing it would seem to be very difficult to ensure that any residual corrosive chemicals that might remain on the surface are removed. Depending on the item's size maybe it could be dried quickly with a hair dryer or placing it in front of a fan.
Thanks! The item has lots of small crevices and even with distilled water, my guess is that a lot of the nasty pollutants (especially the bright green verdigris) will get dislodged and enter the crevices and I won't be able to remove them any more. I was hoping for a more controlled method. I've used a vacuum cleaner with the attachment to get away 90% of the soil, but the rest of it seems stuck to it.

Maybe I could use your idea of distilled water but instead of rinsing, use with cotton swabs and slowly clean the item. It's been buried for a while, so it really is hardened to the surface.

Globalviewer58
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Re: Tool to remove encrusted soil from bronze

Post by Globalviewer58 » Tue Feb 25, 2020 4:03 am

Look at the Victoria and Albert Museum website page, guidelines for cleaning metals. You can decide which methods apply to your situation.

Mr. Rumples
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Re: Tool to remove encrusted soil from bronze

Post by Mr. Rumples » Tue Feb 25, 2020 6:10 am

The Victoria and Albert Museum as mentioned above has good guidelines. Here is another link which recommends some approaches:

https://www.thehenryford.org/docs/defau ... f?sfvrsn=2

What won't most likely be known without a preservationist is whether a protective coating (wax, chemical patina, lacquer, varnish) was applied and what the chemical reactions have been over time. What is "stuck" might be attached to the finish and not the bronze; it might be chemically bonded and thus being bonded to the coating which is bonded to the bronze can't be removed except professionally. In my experience, many museums, both large and small, have curators who are more than happy to look at an object and give an informal assessment. Knowing something of the item's history and where it was made might help determine what was used as a coating.

Keep in mind that soil varies widely. The corrosively of the soil: soil PH, deposits of minerals and pollutants, salt, moisture all will affect the bronze. It won't look like new, and most would say it shouldn't.

If you are near one of the many museums in the south which have Civil War artifacts, I would approach them first since many items on both sides were many of bronze.
Last edited by Mr. Rumples on Tue Feb 25, 2020 6:40 am, edited 1 time in total.

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Watty
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Re: Tool to remove encrusted soil from bronze

Post by Watty » Tue Feb 25, 2020 6:33 am

Caduceus wrote:
Tue Feb 25, 2020 1:48 am
I have a bronze object that's about 80 years old that has lots of encrusted soil on it. I can't use water to wash it for fear of corrosion.
I know nothing about this but if it was outside in the soil then hasn't it already been exposed to a lot of water?

As long as you dry it off when you are done cleaning it how would using water to clean it be any worse?

I don't know if it would be a good idea or not but you might also look into ultrasonic cleaners if the item is small. You can often find these at thrift stores since people use them for cleaning dentures.

Mr. Rumples
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Re: Tool to remove encrusted soil from bronze

Post by Mr. Rumples » Tue Feb 25, 2020 6:46 am

Ultrasonic cleaners are used to clean small bronze objects. The trick however is not to over clean the item. This is the issue with all home remedies. Many work and work quite well but depending on the object it might remove not only the grime, but the finish and it might not do it in a uniform or appealing manner.

HoosierJim
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Re: Tool to remove encrusted soil from bronze

Post by HoosierJim » Tue Feb 25, 2020 7:05 am

Buy a waterpik.

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lthenderson
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Re: Tool to remove encrusted soil from bronze

Post by lthenderson » Tue Feb 25, 2020 9:15 am

It is valuable? I clean lots of non-valuable bronze by just cooking it in a crockpot/slowcooker to loosen up all the paint and other contaminants and then scrubbing with a brush and letting it dry. I wouldn't do that on a rare coin though.

HomeStretch
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Re: Tool to remove encrusted soil from bronze

Post by HomeStretch » Tue Feb 25, 2020 9:20 am

If the piece is valuable, have the restoration done by a professional.

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Kenkat
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Re: Tool to remove encrusted soil from bronze

Post by Kenkat » Tue Feb 25, 2020 9:29 am

In the coin world, people will often use acetone to remove organic materials from coins, including bronze (copper) coins such as pre-1982 pennies. It is non-reactive with the metal. You would want to use pure acetone (not nail polish) and as always, start small to be sure you are getting the results you want. Old school, people used to use olive oil soaks as well so you could also experiment a bit with that.

How much you try yourself should vary with the value of the piece of course as pointed out above.

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Caduceus
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Re: Tool to remove encrusted soil from bronze

Post by Caduceus » Wed Feb 26, 2020 8:23 am

Kenkat wrote:
Tue Feb 25, 2020 9:29 am
In the coin world, people will often use acetone to remove organic materials from coins, including bronze (copper) coins such as pre-1982 pennies. It is non-reactive with the metal. You would want to use pure acetone (not nail polish) and as always, start small to be sure you are getting the results you want. Old school, people used to use olive oil soaks as well so you could also experiment a bit with that.

How much you try yourself should vary with the value of the piece of course as pointed out above.
Do you happen to know any tools that can remove bright green bronze disease without scratching bronze? I've been using a wooden toothpick but am not sure if it's scratching the bronze as there seems to be whitish flakes left on the parts I'm gently scraping.

Mr. Rumples
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Re: Tool to remove encrusted soil from bronze

Post by Mr. Rumples » Wed Feb 26, 2020 8:34 am

Bronze is almost a living organism. Bronze disease is difficult to stop and once stopped, steps have to be taken to prevent its reoccurrence. Below is an article about it:

https://www.brown.edu/Departments/Jouko ... /4867.html

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Kenkat
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Re: Tool to remove encrusted soil from bronze

Post by Kenkat » Wed Feb 26, 2020 8:57 am

Caduceus wrote:
Wed Feb 26, 2020 8:23 am
Kenkat wrote:
Tue Feb 25, 2020 9:29 am
In the coin world, people will often use acetone to remove organic materials from coins, including bronze (copper) coins such as pre-1982 pennies. It is non-reactive with the metal. You would want to use pure acetone (not nail polish) and as always, start small to be sure you are getting the results you want. Old school, people used to use olive oil soaks as well so you could also experiment a bit with that.

How much you try yourself should vary with the value of the piece of course as pointed out above.
Do you happen to know any tools that can remove bright green bronze disease without scratching bronze? I've been using a wooden toothpick but am not sure if it's scratching the bronze as there seems to be whitish flakes left on the parts I'm gently scraping.
The bright green disease is verdigris. I have used a product called Verdi-care that works pretty well in removing it from copper coins. It was developed by a coin collector who also happens to be a chemist but it is hard to get because making it’s just a side job for him. That said, verdigris can permanently discolor the underlying brass or copper so that might be what you are seeing. A wooden toothpick is mildly abrasive but I have used it on coins if the Q-tip method fails. You might try something to soften and lubricate when using the toothpick. Seriously, a little olive oil might help. Dab it on and let it soak for 10-15 minutes, then try the toothpick. Do a small spot to see if you are getting good results first of course.

GrowthSeeker
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Re: Tool to remove encrusted soil from bronze

Post by GrowthSeeker » Wed Feb 26, 2020 9:11 am

Do you want to preserve the green color?
Or do you want it to look polished like new?
I had a house with copper gutters, they were quite old, green from interaction with oxygen and/or CO2 over decades, and this added to the charm of the house.
I'm not a sculpture expert, but does the green discoloration add to the value?
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