1. What are common things that have to be restored?
The most common outdoor pieces that need to get restored are bronze and zinc sculptures, historical markers and plaques and monuments. Granite, marble, sandstone and limestone mounts and bases of the outdoor pieces sometimes need some restoration, especially if installed poorly. Architectural features on buildings made from bronze, zinc and steel, limestone, sandstone, marble and granite often require restoration.
2. What causes the problems (vandalism, environmental degradation, erosion, age, etc.)? Or what is the most common problem? Can you give examples?
All the things you mention cause problems. The most common of these is most likely from continuous exposure to the environment – water freezing and thawing causing expansion and contraction, airborne grit and grime, freezing rain, direct sun/heat, acid rain (sulfides) all cause potential problems.
Vandalism to historical monuments and architecture is a problem in cities. Graffiti is a big issue in some areas - some of the mediums used are abrasive and acidic. If these problems are not treated carefully damage can occur. Others suffer from theft for the value of the metal or for collectable value. Other times vandals are just destructive for no apparent reason.
A not so obvious cause for problems are deficiencies in design and/or execution in the finishing process of the castings at the foundry. Small cracks on the surface could indicate crystaline separation in the cooling process due to uneven cooling of the molten bronze. Abrupt transition in thickness can cause this separation along with the moisture-retaining porosity under the surface.
Heat tears and porous metal under the surface due to molten metal not cooling properly can cause problems from the inside out and repairs must be done properly. Sometimes foundries have left the internal investment material inside the extremities as well as torsos. With the presence of moisture the investment will, over time, leach out of cracks and porous areas in a calcified form laden with sulfides. Weep holes are extremely important in strategic places to allow moisture to drain thus not allowing any standing water to freeze and crack the surrounding area. The weep holes which are about 1/8” in diameter help ventilate and dry the inside of the sculpture.
3. Are there any organizations against the restoration of sculptures? Why?
Usually opposition is due to budgetary concerns. Unfortunately the most resistance comes from not providing funding for proper maintenance in the first place which could prevent major deterioration and expenses in the long run.
Items of antiquity are another topic. In these cases special consideration should be taken. Only conservation work should be done and it should be done sparingly. A lot of this work today is done using optics. These pieces should not be displayed outside but rather protected from the elements and extreme temperature fluctuations.
4. What is the average cost of a restoration?
Cost can range from several hundreds of dollars to thousands. Some factors are:
SCAFFOLDING. Will scaffolding be required? Some monument restorations require elaborate scaffolding and there are companies that have the right equipment and professionals to safely erect the scaffolding. These companies are fully insured and the restorer/conservator should be as well. I consider qualified individuals with the training, experience, expertise and successfully executed portfolio of work to be conservators and restorers in objects of art.
METALOLOGICAL ANALYSIS. Metallurgical analysis can be done on corrosion specimens or on any other factor that concerns the project. The Conservators/Restorers can confer with each other for the best and safest direction for the project.
WHO WILL DO THE JOB. Will a certified conservator be required or will an accomplished craftsmen be allowed to bid?
I would consider choosing the person most experienced and knowledgeable for the task. They should be thoroughly versed in the lost-wax casting techniques and the entire finishing and patination procedures. So, the most qualified person would be a conservator/restorer who is articulate, thorough, mindful of the pitfalls, and capable of performing every aspect of the project to its end.
It takes literally years of experience to learn to successfully make the necessary repairs flawlessly. When older sculptures and monuments were made, the artisians doing the final work were truly masters of their craft. They may have started when they were only 14 years old and by the time they were in their 30’s they were truly masters. The old way is beautiful and should be respected and vigorously protected.
LOCATION. Is the piece easily accessible or hard to get to? Both situations are quite frequent.
INSURANCE. Is there an issue with insurance liability on the particular property?
SCOPE. How much damage or repair is required?
5. What goes into restoring a sculpture? How long does it take? What resources does it consume? How is it done?
An evaluation is done to determine the extent of damage including STRUCTURAL as well as SURFACE damage.
A preliminary inspection is done on the entire surface and structurally if necessary. If a chemical or metallurgical analysis is required this process could take a month or more.
Finishing mistakes are usually not repaired, however bends are certainly something to be addressed. Pieces missing or broken off and beyond repair are a major concern. In these cases the fabrication of new ones will be necessary. Those will have to be sculpted on the piece. The sculpted part would be taken to a studio where an RTV rubber mold or other type would be made. A wax would be made from this mold. The thickness, if possible would be about a ¼” thickness or slightly less. This will help ensure a good casting. The replacement parts would be cast in the lost wax process by a qualified art foundry. The rough castings would be taken back to the studio for the final finishing process.
When a part has to be reattached there are several steps including fitting, welding and proper finishing. Each step should be done carefully so the final surface will look seamless.
After the attachment is complete and patination performed, the sealing process would be next. When all work is complete there should be no evidence whatsoever of the restoration. Sometimes a particular finishing chisel will have to be forged and cut to duplicate a particular surface treatment or modeling.
In addition to parts being broken off and missing, other structural damage can include bends, dents, cracks.
Surface damage is usually corrosion. In this case will the entire piece need to be repatinated or just a portion. If just a portion, then extra time and effort is involved in matching it to the rest of the piece. This is where it is important that an experienced, knowledgeable craftsman is on the job.
Supplies include but are not limited to solvents, mineral spirits, xylene, waxes, incralac*, walnut media, chemicals for coloring. *Incralac is a product I like to use. It is an acrylic lacquer for sealing copper bearing alloys and has corrosion inhibitors. It also provides excellent UV protection.
Tools include a regular toolbox (screwdrivers, pliers, nuts and bolts etc) but also drills, welders, scaffolding, air compressors…
6. Does it cost more to just resculpt the object? Would it be more time and cost effective to start from scratch?
YES it costs more to resculpt the object.
7. What is the value of restoring old bronze sculptures?
Esthetics, beauty, sentiment. Historical value. Human traffic to the site, tourism. People will not be include to go out of their way to visit an unsightly piece of artwork anymore than they would go to a park where the grass is overgrown and full of weeds!