By Ellen Carrlee and Dave Harvey
This is the How-To Manual that accompanies the kit above that we made for the St. Nichlas Russian Orthodox Church in Juneau, Alaska. In August 2009, the Western Association for Art Conservation (WAAC) held its annual conference in Juneau, and the church was the site of an “Angels” volunteer project described elsewhere in this weblog. The brass polishing part of the project was organized and led by Dave Harvey, who has extensive experience caring for metals, dating back to his time working at Colonial Williamsburg. The technique and kit are designed for items that are in active use. Conservators treating museum artifacts would usually mix up their own formula for polishing metal, but the approach for objects that continue to be in regular use and maintained by non-conservators have a slightly different approach. The materials and techniques must be accessible. If you have metals conservation needs or questions, Dave Harvey lives in Los Angeles and can be reached at: email@example.com
Three biggest rules:
- Polishing is abrasive. You are sanding off the surface of the metal.
- Solvent fumes are serious
- Getting well set up is half the battle.
If you need to start from scratch for a large project, setting up a deluxe kit is around $500. If you have a lot of this stuff lying around (table, fan, hairdryer, towels) you could put together a good kit for around $100.
2 plastic tubs ($11.22 Home Depot. Sterilite 66 quarts or 62 liters. ) Nest together. Lidded ones are good because the tub can double as the storage container for the supply kit. Size depends on how large your objects are.
Bucket ($4.47 Home Depot. Helps with transporting hot water)
Teflon tools ($21.50 big, $19.50 small. Talas www.talasonline.com) Non-abrasive special plastic for scraping off wax.
Wooden tools ($2.00 – $5.00 Fred Meyer.) Bamboo skewers, popsicle sticks, toothpicks etc. Really helps with getting candle wax out of threads on screws.
Terry cloth rags ($13.97 for bag of 24 at Home Depot. Large bags also sold at Costco.) Other kinds of cotton rags like old bed sheets or cloth diapers are fine, too. White cotton is the best.
Large bath towel Got an old one at home? This is nice just to place on the table under the wash tubs. (Any color is fine.)
Silver polishing brushes ($7.50 each Talas www.talasonline.com) Made of horsehair and very soft, for getting the polish off before waxing.
Nitrile gloves ($24.41 Fisher Scientific www.fishersci.com Box of 100 pairs) Latex gloves from Costco are OK too, but some people develop an allergy to latex.
Acetone ($16.96 Home Depot one gallon) Used to remove lacquers and other coatings from the brass. Also, after polishing and rinsing, acetone removes remaining residues and helps evaporate any water in crevices.
Hair dryer ($14.99 Fred Meyer) Used to help remove wax when submerging in hot water isn’t a good option.
Hot air gun ($29.50 Home Depot) Gets much hotter than the hair dryer and is used only to heat the metal gently before waxing.
Renaissance Wax ($21.00 Talas www.talasonline.com 200mL can) For protective waxing of the surface after it is clean.
Mylar ($53.50 for .005” thick 20” x 50 feet Talas www.talasonline.com) Polyester sheet film that can be cut into drip-catchers that are almost invisible. When they get spattered with wax, they can be peeled off and replaced, saving you from having to polish as frequently.
Scissors ($10.00 Fred Meyer) For cutting the Mylar
Small mat knife or X-acto ($3.00 Home Depot) For cutting the Mylar
Wright’s Copper Cream ($4.29 Fred Meyer) For polishing. Avoid anything that has “ammonia” in the ingredients.
Jet-dry ($5.29 Fred Meyer) Contains non-ionic surfactant. Any rinse aid that says “non-ionic surfactant” on the label is OK, but avoid dyes and perfumes. This container has blue color in the plastic bottle but the liquid itself is clear.
6 foot folding table ($175 Costco) As a working space if you don’t already have one
Fan ($18.00 Fred Meyer) To help get rid of the fumes.
Brass is the name given for a metal alloy that is made mostly of copper but also includes zinc. There may be small amounts of other metals present as well. (Bronze is a copper alloy that includes tin.)
Brass is often polished with harsh abrasives that can leave scratches in the surface and residues that harm the brass over time. Many commercial polishes contain ammonia as a cleaning and degreasing agent, but it also reacts with the copper. If there is already tension in the metal, the ammonia can cause a phenomenon known as “stress corrosion cracking.” This is well known among folks who repair clocks and watches because of the damage it causes to the gears. If chemical residues are not well washed away, they continue to attack the metal after the polishing is done. For things in everyday use with a limited life span, the aggression of these commercial products is fine. For heirloom pieces, artwork, clocks, and museum items to be preserved for hundreds of years, more gentle techniques are needed. Most metal polishes contain fine abrasives. Pinkish or reddish polishes contain iron oxide, which is much too abrasive for shiny silver or brass. Steel wool and naval jelly are too harsh as well. The rule is to use the gentlest polish possible. Remember, polishing is essentially sandpapering.
Brass in need of polishing often has degraded lacquer (can appear as dark tarnish areas,) candle wax, dirt, and corrosion products on the surface, including greenish organometallic corrosion that is often due to the interaction of impurities in the candle wax with the brass. The green is often copper sterates or copper oleates. These are caused by organic acids in the oils of the waxes reacting with copper ions from the metals.
If the item is completely brass, you can follow the simple instructions below. If it includes any other materials, such as wood, ivory, paint, and so on the technique is slightly different so as not to damage those parts. For example, you should not submerge it in water. For the votive table we polished, it had wood underneath and careful use of heat from a hair dryer (not a hot air gun, that would be too hot) helped loosen the wax.
GETTING SET UP
Make a workspace with a large table covered with a large bath towel. We used the gift shop area with a station for wet work and a separate station for waxing. There was a spot outside on the front porch for dirty acetone-soaked rags. We set up the waxing station near the back door for ventilation. Fumes from the acetone, polish, and wax can make the work unpleasant and make you feel really lousy. Setting up a fan to blow the solvent fumes away from you is a good idea as well. If you do feel lightheaded after doing this work, you probably had too much solvent exposure. Your liver will be working hard to clear it out of your system, so be kind to your liver and avoid drinking alcohol that evening.
If the brass item comes apart, like a candelabra or a votive table, you MUST document where all the parts and piece go so you can reassemble easily when you are done. Photographing is helpful. If you use a digital camera or even a cell phone camera, you don’t have to download the images, just use the playback on the camera to check and then delete the images later after the object is reassembled. It can help to make tags or labels of where things go. If possible, only remove a few at a time so they are easier to keep track of.
Fill tub #1 (the wash water) halfway or a little more with tap water as hot as it can come out of the bathtub faucet . You only need to fill up the tub far enough to cover whatever it is you are polishing. It helps to have two people to carry the tub. If you are on your own, use the bucket to carry hot water to the tub. Add just enough non-ionic rinse (Jet Dry) so bubbles come up when you shake your fingers around in it. Tub #1 will be for cleaning. Keep the Teflon scrapers and some rags handy near this tub.
Fill tub #2 (the rinse water) the same way. It will be for final rinsing after the brass is clean, right before waxing. Keep the horsehair brushes and some rags handy near this tub.
Set the acetone container under the table with some rags handy. Do not use acetone or other chemicals around flame or sources of ignition, and do not smoke. If the fumes are annoying, you might want to do the acetone work near some ventilation. You might want to have a big ziplock bag to use with towels that become too stinky so you can seal them up and set them aside, or even set them outside on the porch. A fan might also be helpful, positioned to blow any acetone fumes away from you. Acetone is the main ingredient in fingernail polish remover, and while there are many solvents that are much more toxic, some people are quite sensitive to acetone and it is smart to reduce exposure. An open door or window can help, and in nice weather this activity might even take place outdoors.
You have several weapons to combat the candle wax, stain and corrosion:
- Hot water
- Teflon or wooden tools
Soak the brass parts in tub #1 of warm wash water to dissolve dirt and soften the wax. Use the Teflon scrapers to loosen the warm candle wax and wipe it off the scraper onto a towel you keep handy. You can scrape and dip repeatedly in the warm water to get the wax off, or even keep the piece immersed in the warm water while you work on it. Once the candle wax starts getting sticky and goopy, it is time to get fresh hot water. Wrapping the back end of a plastic pen in a rag and twisting into the candle hole helps clean it out. Anything that is softer than the metal and won’t scratch the metal is generally OK as a tool. Bamboo skewers (like those used for shish-ke-bobs,) toothpicks, and popsicle sticks are nice too.
In order to remove the last bits of candle wax and the degraded lacquer, put a little acetone on a towel and rub it off. Use the smallest amount possible. Keep the lid on the acetone as much as you can and try to limit how many rags are being used, or else the fumes from the acetone will make your work unpleasant. It is best to do this work in a well-ventilated place.
Rub a small amount of the polish onto the surface of the brass with the sponge that is included in the jar. Rubbing the metal with the sponge ought to help remove most areas of stain. The gentle abrasion offered by a terrycloth rag with polish on it is helpful, too. Polish seems to work a little better if it sits briefly on the surface. Brownish tarnish areas will come off with enough rubbing. The towel will have dark stain on it as you polish, and some of that is the metal itself, so the idea is NOT to polish until your rag comes up clean, but until the stain is gone. Sometimes going back and forth between the acetone and the polish is helpful.
When you have cleaned it as well as you can, use the rinse water in tub #2 and the horsehair brushes to remove the polishing residues. Dry the object with a clean cloth. If there are two people working on the project, one person can be doing the dirty cleaning off of candle wax and using tub #1, and another person can be doing the less-dirty activities of rinsing at tub #2 and waxing. If you are working by yourself, it is good to change your gloves before going to tub #2. Otherwise your gloves might get candle wax and dirt residues on your freshly cleaned brass.
Microcrystalline wax provides a layer of protection from dirt, wax, fingerprints, grease etc and will make your polishing job last longer. The Renaissance wax is also a sacrificial layer that will take a lot of soiling with it when it is removed during the next polishing. We use Renaissance microcrystalline wax because it is of known good quality, does not need to be pre-melted before use, and will not cause corrosion of the brass. However, it does have solvents in it and you should take care with breathing it. It is not a natural wax like the beeswax in the candles, it is a petroleum product. Wipe down the brass with acetone on a clean rag just before waxing. This will remove grease or fingerprints from the surface as well as help remove any water from crevices. The cleaner the surface, the better the wax can form a good coating.
Pre-heat the brass piece you are working on evenly all over with the hot air gun. Do the heating gradually over the whole piece, not just in one spot. Do not touch the nozzle of the hot air gun or you could be burned. Heating opens the pores of the metal and makes the wax flow on and penetrate the metal surface much better than if it were applied cold. It is difficult to get the metal warm enough with a simple hair dryer. When the metal gets almost too warm to touch with your fingers, like a hot muffin, it is ready. Dab a little Renaissance Wax on a clean rag and then barely coat the surface of the brass. Make sure there are no shiny spots left and the brass is completely coated. Remove the lid of the wax container only long enough to put some on a rag. Apply it to the surface with one rag, and then right away take a second clean rag and buff like crazy. Use a fingernail inside the cloth to get buildup of wax out from the small spaces and grooves. It is a good idea to walk away from the waxy rag while you polish so you are not standing in the fumes.
When you are done with the project, lay out all the used rags to let them air dry overnight. Choose somewhere where no one will be, as it will get stinky from the fumes. When they are dry, wash them with detergent like a normal load of laundry in the washer and dryer. They will come out pretty clean and can be put back with the kit for future use.
Your polish job could last for years if you avoid handling the brass with bare hands and can keep candle wax drips off of it. Wearing cotton or plastic gloves or even having a clean towel between your hand and the brass can prevent fingerprints that etch into the metal over time.
There are “Dripless” candles of higher purity that might cost more but cause less damage. We made custom-fit layers of clear plastic Mylar film to act as drip guards for the candelabras and votive tables. These are optional but might make your polishing job last longer.
How long does it take and how many supplies are needed? Well, 5 or 6 people (professional conservators) working for two days (about 14 hours) polished one large floor-standing candelabra, one large votive table with a great many candleholders, and another smaller votive table with only a few candleholders. They used up 1/10 bottle of Jet Dry, 1 ½ cans of polish, 2/3 can acetone and most of one can of wax. A few months later, 3 people (two conservators and a volunteer) took 12 hours to polish the second floor-standing candelabra. (The 21 little individual candleholders that unscrew from the candelabra took those 3 people 3 hours.) They used 1/10 bottle Jet Dry, one can of polish, 1/3 can acetone, and ½ can of wax.