Vero Beach Museum seeks advice

[JAZ]

We are seeking information on the types of chemicals and filtration
systems that can be safely used in a fountain/pool that includes a
bronze sculpture. Currently we treat the water as if it were a
swimming pool, but are looking for alternatives. Can you advise us
as to the best system and chemicals to use that will have the least
detrimental effects on bronze sculptures?

James D. Belknap
Registrar
Vero Beach Museum of Art
Vero Beach, FL 32963-1874
772-231-0707 Ext. 104
jbelknap@vbm.org

I received this message through the New England Sculptors Association, of which I am a member, and am posting it here in the hope that someone will know the answer. In the process of speaking with Mr. Belknap we had an interesting conversation about the impact of the recent hurricanes on the sculptures there. A 12' tall x 14' wide Nancy Graves steel, brass, bronze and aluminum sculpture was completely destroyed. Two others approximately 20 feet tall, including one made of aluminum, were not damaged. In the case of one of those, a piece by Luella Davies, museum curators discussed whether to anchor the piece, which stands on a forty foot square concrete base, seemingly secure. To convince others that it needed to be anchored, one of the curators sprayed the concrete with water, then he and two or three other people were able to push the sculpture because it hydroplaned. Needless to say, they installed anchors.
If anyone has an answer to the question about water treatment for the fountain with the bronze, that would be great.
JAZ

[JAZ]

"....In the case of one of those, a piece by Luella Davies, museum curators discussed whether to anchor the piece, which stands on a forty foot square concrete base, seemingly secure. ..."

I apologize to the Vero Beach Museum. I've just looked at their site and the artist of the sculpture that they saved by bolting it down was Hayden Llewellyn Davies.
JAZ

[fritchie]

We are seeking information on the types of chemicals and filtration
systems that can be safely used in a fountain/pool that includes a
bronze sculpture. Currently we treat the water as if it were a
swimming pool, but are looking for alternatives. Can you advise us
as to the best system and chemicals to use that will have the least
detrimental effects on bronze sculptures?

James D. Belknap
Registrar
Vero Beach Museum of Art
Vero Beach, FL 32963-1874 ..... etc. .........
JAZ

My background is chemistry, and I have worked with (my own) bronze sculpture for about 15 years, so I’ll take a stab at this, but my answer is theoretical and not based on practical experience.

Water treatment in swimming pools generally uses some form of oxidizing chemical, as the least costly and most effective method of preventing growth of plant or animal organisms (read: green algae or scum, and infectious agents such as bacteria).

The best known of these oxidizing chemicals is chlorine, which is introduced as a gas, as a form of chlorine bleach - typically hypochlorite - or as some milder chlorine-containing agent. I would expect that any of these materials, over time, would remove patina from bronze if it is in contact with the water, even as a spray.

My first thought is to use a bubbler in the pool. Simply have a pump that forces air to bubble through small holes near the bottom of the pool. Air, of course, contains oxygen, which is not as destructive as the chlorine compounds, but which will have many of the same biocidal effects. Also, small quantities of a copper compound, such as cupric sulfate (the common blue crystals), might be added. Oxygen and agitation alone might not prevent growth of algae (scum), but many of these scum organisms are killed by very small amounts of metal ions, and cupric probably would be best for the sculpture.

Hopefully, you will get answers from someone with actual custodial experience, but these facts should provide a beginning. Let us know what you decide!

[sculptor]

Couple thoughts:

One would expect a chlorine water treatment to eventually lead to bronze disease (copper chloride) as described by Arthur Beale in the article in The Fire of Hephaistos----if memory serves this was recommended reading by Mark?

further:
sulfide corrosion (black spots) has been a major concern in museums, so introducing sulfer into the environment of a bronze sculpture might best be avoided which should exclude the use of cupric sulfate from our list

and, it seems that most acids are corrosive in nature

so:

Perhaps a mildly alkaline environment and a sacrificial sealing coat for the sculpture would be a better measure where conservation is a major goal?

Thoughts?
rod
sculptor (http://http://home.mindspring.com/~mandali/index.html)

[fritchie]

Couple thoughts: ......
further:
sulfide corrosion (black spots) has been a major concern in museums, so introducing sulfer into the environment of a bronze sculpture might best be avoided which should exclude the use of cupric sulfate from our list .............
Perhaps a mildly alkaline environment and a sacrificial sealing coat for the sculpture would be a better measure where conservation is a major goal?
........
rod



Rod - Sulfate (SO4)2-, with sulfur in a +6 oxidation state, and sulfide (S2-), with sulfur in a -2 oxidation state, are as far apart in properties as sulfur can get. Any sulfide in an oxidizing environment, such as a bubbling pool, will be converted fairly efficiently to a higher oxidation state (even though copper itself has a special affinity for sulfide), so I don’t think that is a problem.

Your post does give me an opportunity to reinforce one point I should have emphasized earlier. The best line of defense, though time consuming and of some expense, is periodic reenforcement of a wax or other protective coating.

We have had other posts on this subject (waxing or other coating). Ideally, protective coatings should be removed and renewed every few years, according to need, but in practice even museums have limitations of attention and money. All these considerations are important.