Editor's Note: The preservation of finds is every detectorist's responsibility. Proper cleaning can be an important part of that process, but whatever the method, it should always be accompanied by appropriate caution. First practice on items of little or no value until you have perfected your technique and are confident that it can be safely employed to good effect on better finds. Remember, too, that results may not be reversible; and for that and other reasons, many collectors and conservators may prefer that certain items remain uncleaned. There is excellent information in the following article. Please use it wisely and well.
One of the most common "keepers" metal detectorists dig is buttons. This is especially true at sites which predate the turn of the 20th century. Most of these fall into one of several types: one-piece flat buttons, two-piece buttons, pewter buttons, or tombac buttons. Each of these button types requires a different cleaning and preservation method. All of us, myself included, have made mistakes in judgment with cleaning methods, but I'd like to share some of the methods and techniques that have worked best for me in the past 20 years of metal detecting.
First, let's talk about flat buttons. There are millions of these underground, and most folks don't give them a lot of thought. The lowly flat button can be interesting, though. The backs of flat buttons frequently have either a maker's mark (company name) or a quality mark. Both types of marks on the reverse of buttons are called "backmarks." Quality marks were the manufacturer's way of promoting their product. Typical quality marks include "Extra Rich," "Rich Gold Color" (or "Colour"), "Treble Gilt," "Best Orange Gilt," or any combination of those words ("Extra Orange Gilt," for example). While quality marks seldom tell us much, makers' marks can sometimes help to date a site. (I'd recommend the books Dating Buttons and Uniform Buttons of the United States by Warren K. Tice for some good information on button manufacturers and their date ranges.) Often the big problem is being able to identify the buttons we dig. I used to use water and a toothbrush to reveal the details on dug buttons, but through the years I've realized that this method isn't all that great. Many times I ended up removing all the patina, and with it the backmark as well.
Gradually I started experimenting with a different method. I get a toothpick or wooden skewer- I prefer thin, wooden shish kebab skewers by far- then hold the edge of the skewer flat against the back of the button, as if I were holding a charcoal stick and making a rubbing of the button. Do this cleaning method without water: the button must be perfectly dry. The advantage of this toothpick method is that it keeps the patina in the grooves where the backmark is stamped. (On the other hand, as mentioned, a toothbrush removes all of this patina, and you're left with no contrast to aid in reading the backmark.)
If the backmark or quality mark on a flat button is raised rather than incuse (stamped in), you'll have to scrape the corrosion off very carefully, just until you start to see the tops of the letters. Don't go any deeper into the corrosion than that- but when you have a rough idea of what it says, you can then work on individual letters as needed. Afterward, you can lightly rub the high points with your index finger, and the natural oil on your hands will bring out the design even more. The oil on our hands adds contrast to the highest points on metal objects with patina, and I have even used this light brushing of a finger over the high points on large cents and Shield and "V" nickels in order to read the dates after cleaning.
Before cleaning a button with the "toothpick" method outlined above, be sure to check carefully to see if there is any gold or silver gilding to preserve. If you find a button that has lots of gold gilding, I'd recommend either Aluminum Jelly or Naval Jelly. Do not use a toothbrush on these, either. This holds true for gold gilding on both one-piece and two-piece buttons with a good bit of gilding remaining. The method for using Aluminum Jelly is outlined later on in this article.
The peroxide method works well if you have recovered a flat button without a backmark. These are usually the large, older flat buttons, Colonial types without backmarks, and what our British friends refer to as "dandy" buttons (very large, flat Colonial period buttons). The peroxide method is simply this: in a microwave oven, heat up some normal, durgstore variety hydrogen peroxide in a glass container. Then drop the button in. All of the crust and dirt will be removed. Do not breathe the vapors, and be sure to do this in a well-ventilated place. Also, be careful not to put anything metal in your microwave.
Tombac buttons are named for the metal they're made from, an alloy of copper and zinc. They come out of the ground with a silvery or gunmetal colored shine. Tombac is brittle, and these buttons are often broken rather than bent by the plough. They can also be identified by the fact that their backs appear turned, as though made on a lathe; and their shanks are made of brass and applied as a separate piece to their backs. Due to their coloration, some detectorists confuse them with pewter or even silver buttons. In terms of cleaning, I know of no way to remove fertilizer corrosion from tombacs. At best, removing this green corrosion takes some work and elbow grease, and the results are hardly stellar. On the other hand, Aluminum Jelly seems to cure tombac buttons of light tarnish. Aluminum Jelly can be obtained at most hardware stores.
Pewter buttons must be cleaned very carefully. I usually place them in a Ziploc bag immediately after recovering them, to keep them moist, then take them home and soak them in water and gently toothpick them, using extra care around the edges (which will typically start to flake over time). I always toothpick from the center of the button toward the edges (the edges will be weaker and more prone to break), using less pressure as I approach the edge. After cleaning and letting them thoroughly air-dry, it is important to coat them with something to stabilize them. I use a 50/50 mixture of Elmer's glue and water, painted on with a small brush. I have heard of others using a thin coat of urethane (painted on and then thinned out across the front of the button) to preserve them and prevent them from continuing to flake away at the edges, but I still prefer Elmer's glue since it is completely reversible and can be removed by soaking the button in soapy water.
Again, if you find a button (one-or two-piece) that has lots of gold gilding that you'd like to preserve, I'd recommend either Aluminum Jelly or Naval Jelly. I do not toothbrush these, since a toothbrush will often remove some of the gilding. Instead, apply Aluminum or Naval Jelly to the button. Let it sit for about a minute and gently swirl it around with a wet wooden skewer that has been soaking in water to make it less abrasive. The crust will melt away from the surface of the gold. Rinse. Use multiple applications until the button's remaining gilding is fully revealed.
Once the Aluminum Jelly has done its work and the cleaning is done, I rinse the button thoroughly with a little soap to neutralize the acid in the jelly. (I also do this if I am going to stop work on the button for an extended amount of time.) I hold a cake of soap in my other hand, between the faucet and the button, so that the soapy water falls over the button. I don't apply soap directly to the button, but use just the soapy water mix running off my hand from the faucet.
The cleaning process for gilded buttons can take a long time, depending on the detail on the button, but the more care you take with it, the more gold gilding you will have left at the end. I have spent an hour or two cleaning ornate buttons, but I spend comparatively little time with gilded flat buttons. When you swirl with the toothpick, you'll be able to feel the smooth gilding underneath the dirt and crust. Don't push into the gilding, as this will remove it. Instead, just "ride" the toothpick along on top of the gilding.
Another tip: toothpick from areas with gilding toward areas without gilding. That way you won't pull up the gold that remains. If you need to see the backmark (for example, on a gilded two-piece military button), and intend to treat the front with Aluminum Jelly, then I would advise doing the Aluminum Jelly work on the front first. Leave all of the dirt and corrosion on the back until last. Then let the button dry completely and use the toothpick method on the back. Anytime you use water, toothpicking runs the risk of losing the backmark; so, it is important that a button is completely dry, so that the patina will remain in the grooves of the backmark. This will help to give contrast so that the backmark may be read.
Although some folks like to use an olive oil soak on two-piece buttons, I never use olive oil. I have found that olive oil will be absorbed into the button, and then slowly leak out for years. Olive oil will also make the button more fragile. In some cases, even water can cause a two-piece button to disintegrate. So, use your best judgment. If a two-piece button has no gilding, I've started using just a dry toothbrush on these, and I've had good results. I've then touched up the design with toothpicks as needed, and used the natural oil from my fingers, brushed lightly over the highlights, to bring out the design.
Two-piece buttons are all different. I've had the best luck with Aluminum Jelly in cases awhere there is a protective "crust" over the whole button that has served to protect the gilding during the button's long sleep underground. Heavy corrosion and rust globules are another matter entirely, and I have no easy answer for you in those cases. Soil type has a lot to do with it, too- as well as the presence or absence of fertilizer. While most buttons can be greatly improved by careful and thoughtful cleaning, some buttons are just beyond help.
The toothpick method will work on most brass items with designs that you'd like to be able to read. I use the same approach when cleaning suspender clips that I find. I also use it on wick turners off old oil lanterns, and on the front of toe taps, where there are frequently patent dates stamped in.
Be sure that you try any cleaning method listed here on a less valuable find first. Experiment with other buttons before you attempt to clean any button of high value. I swear by all of the methods outlined in this article, and if used correctly they should at the very least enhance the display quality of your buttons. There are buttons out there worth hundreds or thousands of dollars, and some that look like ordinary flat buttons except for the backmark. I hope that this article will give you a few new ideas for cleaning, preserving, and improving the display quality of your recovered buttons.
WILLIAM PLUMMER is a music teacher, conductor, and pianist. He has been metal detecting since 1992.