This presentation is part of the International Cemetery Preservation Summit, April 8-10, 2014 Niagara Falls, NY.
Maintaining Leadworks for Cemetery Monuments and Mausolea by Angus “Gus” Fraser and David Gallagher
Gus: Mount Auburn Cemetery in Cambridge, Massachusetts. Mount Auburn is a National Historic Landmark. It was the first of a rural or garden cemetery in the United States and set the model for many rural cemeteries to follow. It’s about 175 acres. We straddle the line of Cambridge and Watertown, Massachusetts. I hope that if any of you have not been to Mount Auburn that if you’re in the Boston area you’ll come and visit and see the grounds.
Today, David and I are going to talk about lead, which is now a much maligned material that historically, though, was used extensively in monument and mausoleum work. We found of interest because the more we looked at Mount Auburn, the more monuments we repaired and mausolea that we pointed, the more lead we saw. We knew that we had to learn more about the material and the forgotten skills needed to use it in order to best preserve the historic fabric and carry out our role as stewards of the historic site.
Lead has been used for thousands of years in the building trades, in general, but seems to have been very popular in the monument-setting trade for a period in the late 19th and early 20th centuries. It’s fallen out of favor, in general though, since the 1950s as new materials have come along. In the last few decades, especially as its potential toxicity, has required stricter regulations for its handling and use. When I arrived at Mount Auburn in the last 1990s, lead wool in use occasionally for repair and repointing of mausolea primarily. We noticed many other applications and forms for its use and realized that we would have to reacquire some of the skills necessary to use it properly.
Just a brief outline of what David and I will talk about today. First I’ll discuss briefly the properties of lead that make it a valuable material, talk about some of the historical sources and uses of it, and it’s historical use at Mount Auburn. Then David is going to discuss some projects recently carried out at Mount Auburn.
Before I go any further, I would like to thank the NCPTT for a grant that funded some additional documentary archival research that we did as well as a half day symposium that we had at Mount Auburn where we invited regional preservationists, hoping to learn from them and also share some of our experiences. We will also be producing a short video to demonstrate some of the techniques we use in the field that will be eventually posted on the NCPTT website.
Physical characteristics of lead. Lead on the periodic chart of elements is represented by the symbol Pb. This stands for plumbum, which was the Latin word for lead. It reminds us of the Roman’s extensive use of lead pipes for their waterworks. Lead is classified with the group of what are called the poor metals. Primary characteristics that these metals share is a low melting point, which is crucial for lead.
Lead melts at 622 degrees Fahrenheit, unlike gallium which actually melts–which is another metal that I learned about–at room temperature or in your hand. Lead has a little bit higher melting point than that. Also, it’s relatively soft and malleable at room temperature which means that it’s very workable in the field which is a very valuable characteristic for its use in monuments.
It also readily forms a stable and insoluble protective layer when it’s exposed to weather. This layer, you will see it either as a whitish film that’s lead oxide or a slightly thicker, darker lead sulfite that shows on the surface of the lead. It’s very stable and durable in outdoor environments.
I should mention that it’s resistant to some acids including phosphoric and sulfuric acids. It’s weakly affected by hydrochloric and hydrochloric acids, which are often used in masonry cleaning. It does corrode or will dissolve in organic acids over a period of time, including acetic and oxalic acids. Interestingly, vinegar or acetic acid is used in the Dutch process and the Dutch Boy on the National Lead Company medallion there. The Dutch Process is a process for creating white lead which was used in paints and, hence, the Dutch Boy from the Dutch Boy Paints of the early 20th century.
In terms of color, it’s a chrome-silver when it is melted to a liquid, bright bluish-silver when solid, and then it turns to a dull gray when it’s exposed to air. Then it may acquire this patina of white film or a darker lead sulfite surface.
It’s a very dense metal. It weighs about 708 per cubic foot, which just for reference is about four times the weight of a cubic foot of granite. That density is a positive and a negative, because when carrying any great volume of lead around you certainly have a … especially when it used to be used in the roofing context.
Where does lead come from? Lead is a pure metal. It’s rare in nature. It’s usually smelted out of other minerals and ores that may contain zinc, silver, or copper. It’s low melting point make it relatively easy to produce. Lead beads have been found in modern-day Turkey that date back to 54 BC. The Roman Empire was the largest, early producer of lead. Production was thought to have peaked during the first two centuries AD. Ancient Roman lead mining has been documented in modern-day in Central Europe, Britain, Balkans, and the Middle East.
During the Colonial Era in America, lead was primarily imported. In the 19th century, lead was discovered in Missouri and what became to be known as the Lead Belt. Here we have a little engraving from the Lead Belt of mining and then a little smelting house to the side. On the right of the picture of lead bound up with calcites out of which it would then be smelted. For reference, that’s about two- or three-inch wide piece of mineral.
Lead has historically, widely been used in building. It’s workability and durability and it’s relative abundance made it useful in many trades. In Greek and Roman architecture it was used in pinning together the pieces of columns, shafts of columns. Here there is an engraving showing an iron pin that is set in a lead socket. Lead provided some ability for movement but also protected the iron from corrosion. On the right we have a lead water spigot from the Roman time. Then we have a beautiful example of lead roofing at the bottom right.
We know that lead was available and in frequent use in the construction trades. We know from physical evidence and archival sources, we know it became a popular material we use in the monument industry. One of these archival sources is the Monumental News. Monumental News was a trade magazine that was first published in 1889, and was continually published in one form or another until the early 1960s at which point it changed its name. I believe that I read somewhere that, essentially, it’s still produced under a different name as a trade magazine for the stone industry.
It contained many ads for lead. It was most often wedge lead which is specific to the monument trade. Most interesting, though, in the Monumental News magazine journals are the Ask and Answer section and the Hints to the Handyman section. In these sections, tradesmen would respond to questions that had been asked in previous issues about monument making, setting, or care. Then they would provide instructions for various work and have several references for the use of lead in these sections. We have here an ad that’s on the top with wedge lead being available among monument settings materials. I mentioned primarily I talk about wedge lead in the Monumental News.
This article is actually from a different magazine, but it’s similar to one that you will find in Monumental News. This article to the right came from a Montgomery Ward mail order catalog for headstones and grave markers. Clearly it’s targeted towards the do-it-yourselfer. It has full instructions for setting a monument ordered through the mail from Montgomery Ward. For granite monuments the recommend the use of wedge lead placed down along the base. The process when you place wedge lead shims at the four corners as you were placing the die. Then after it was in place, to go around the outside and tamp wedge lead in around that joint.
There are also many references to lead putty in Monumental News. There were various recipes. Lead putty was kind of a precursor to setting compounds today. Like I said, there were various recipes but primarily it would be white lead mixed with stone dust and then some linseed oil or another thickening agent that would form a paste. This paste would then either be rolled out and then bagged and held for later use. In the field, it could be kept in a tub and then rolled out in the field. Similar to the use of setting compound today, you would place the stone on wedge lead shims and then go around the outside and you could either point with the lead putty or you could lay a rope around the outside of the monument as you set it.
White lead is not something that you can purchase today except in very small quantities. It’s still available for artists, for painters who sometimes like to mix up their own paints. They prefer to use white lead for various reasons. We ordered a couple of small packages. They are $20 for … I think it’s measures in grams, and mixed up a little bit of it just to try to see it how it worked in our shop. This is an example here. I think what’s really nice is the color that you get. We used granite stone dust mixed in the white lead. The color was a very great match for the monument, for the stone itself.
In the 19-teens, Monumental News alluded to a small trend in lead lettering. There were several articles on how to do this. You would cut out a small groove corresponding to the letter in the monument, and then you would tamp in sheet lead. Then these little holes would key the lead as you tamped it and it would form to those holes and the lead would key to the grooves. We’re fortunate at Mount Auburn to have either additional examples and you can see more details in the holes and the grooves.
At Mount Auburn we have one example of lead lettering. I think it’s especially nice. Unfortunately, this monument has not been cleaned. On close look, the lettering is just fantastic. It shows great craftsmanship. In an area where the stone at the mid-space is fractured, you can see the little hole where the lead was tamped in and keyed in. I assume it’s that way on all the lettering. It’s a great example of craftsmanship.
Also at Mount Auburn, we have an abundance of information in our own archives. Here are two letters referring to lead. These actually both refer to the R. H. White Mausoleum on the grounds of Mount Auburn. The letter on the right refers to the setting of the columns of this mausoleum on sheet lead. The monument granite dealer said the lead is to be cut back one-inch from the edge of the columns. The columns are not to be caulked until the mausoleum is complete. I assume he was talking about using white lead to point the joints because the monument is leaded throughout the mausoleum. On the left there is a letter from the last owner referring to perpetual care for his mausoleum and the pointing of the joints in lead.
Here’s a picture of that mausoleum. I think the lead is an especially nice effect aesthetically here in this kind of detail. You can see the dull gray of the lead is very sympathetic to the granite. It does have a bit of a grayish-white patina from corrosion. That’s stable corrosion on the surface. Then you can see the darker, more black, corrosion in this protected area.
One of those letters refers to perpetual care for this. It does have perpetual care and it’s been repointed several times over the years. Here you can see the original lead that they did not take out as they were repointing. Probably as you tamp it, it can go too far into the joint so then you have to go back over the top. This would have been white lead here and then they had lead wool that you can identify from the strands that David will talk about later. They went back and repointed over the white lead with a lead wool to repoint that.
We also have a number of work cards referring to setting and leading monuments over there. Then this is a perpetual care estimating sheet that talked about washing and leading the front of a monument or mausoleum.
We know that there’s a lot of lead out there. We don’t know that it’s all original. It could have been used in various repointing or repair campaigns. We had to ask ourselves is this an appropriate material to be using as we move forward? Most all of us are preservationists here or preservation-minded. We have to consider the original materials and historical accuracy. What function does any material … What function does it do between the stones?
First of all, it forms a cushion between the stones when you’re setting them. Lead is great at absorbing imperfections or then after the monument has been set for absorbing movement in the stone [inaudible 00:18:32] contraction. Lead is malleable and can absorb that movement so the stone itself is not damaged.
Then joints should keep water from penetrating the monument or mausolea. Here lead is perhaps not perfect material. Doesn’t for any kind of chemical bond with the stone. It merely fills a gap and, therefore, water will be able to get in through capillary action. Even through the tightest joints and soaking rain there will be some moisture penetrating that joint. On the flip side, water is able to, through capillary action, again be drawn out of that small gap between the lead and the stone.
In setting of monuments, you’d want a material that’s relatively efficient to use. Lead, in some cases, can be very efficient to use as I showed in the description of setting a monument for using white lead. That can be a pretty quick and efficient process to set the monument and then tamp in lead around the outside.
It’s definitely a durable material. Much of what we see on the grounds a Mount Auburn, that we know or assume to be original is still in fantastic shape. Also, it’s maintainable. If a lead works itself out of a joint, it can easily be
tamped back in. It also can be recycled. Lead, if you’re using a molten or poured lead, you can recycle it almost indefinitely over and over again.
Then aesthetically, is an attractive joint? I showed you the R. H. White Mausoleum where at least the lead is a neutral presence on the monument. Aesthetically it can be pleasing. Also, you can get a very tight joint using lead which was probably also one of its attractions. The wedge lead can be an eighth of an inch or slightly smaller so you get a very tight joint, much tighter than you can get using a mortar or often using sealant.
On a case-by-case basis, we tend to look to see if lead was an original material and then judge using these criteria whether is an appropriate material to put back into the monument. We also consider what our options are. This is a monument that was set in about 2005 in a beaded silicone. You can see that that’s already starting to deteriorate. It’s a relatively good color match, I guess [inaudible 00:21:28] silicone sealant but it’s already started to deteriorate. Then this is use of setting compound that’s in frequent use today.
When dealing with lead, obviously, it’s potential effects on the worker are something to take seriously. I urge anyone who is going to be using it in a repair or preservation project to develop their own safety protocols. Lead enters the body only through ingestion or inhalation. If you breathe dust or if you get lead on your hands and then it gets on food or something that you’re drinking, it can then be ingested.
It affects many systems of the body. It can be acute or a chronic problem. There are OSHA standards for lead exposure. They regulate exposure limits and provide guidance for testing lead in air. Then for any workers, testing lead is in their blood. Lead dust and fumes pose the biggest threat. That’s primarily in industrial processes for paint removal or when using melted, molten lead.
Basic precautions to take. If you’re removing lead, you can wet the surface. That will keep any dust down. Wear gloves and a dust masks. Obviously, wash your hands frequently. Change clothing after the workday, therefore, you won’t be taking any dust home with you. Use dust masks, as I mentioned. Limit your exposure. Work in a well-ventilated area. All of our work is done outside and it’s going to be well-ventilated, but we will take the other precautions.
I’ll now turn it over to David and let him talk about some of our recent projects at Mount Auburn using lead in various forms.
David: Good morning, everyone. Thanks, Gus, and thanks again to NCPTT for our grant and for putting on this conference. I’m just going to … I’ve been told I have six minutes it’s going to be quick. Oscar Wilde said, “No passion is trivial that’s pursed passionately.” For some reason, Gus and I have this passion for lead. It’s inert. It’s simple and it’s deadly, which you can tell by looking at Gus and I. We’re drawn to it.
This is going to be quick examples of how we use it here. You can see the molten lead is being used to anchor these cast iron posts. This are the different forms that it comes in. On the left we have the lead wool which you can see it’s like a steel wool except extruded lead. On the right you see the lead ingots that are being in the furnace. That’s about usually what we use is the 50-pound. I don’t think Gus addressed this specifically, but it’s all recyclable. I think Gus did mention this. We melt anything we take out–wool, wedge lead–we put into a pot and we’ll use again.
A related product to the lead is oakum which is a petroleum-infused jute or hemp, which is used a lot in boatbuilding because it will expand. When this boat goes in the water, the planks expand, the oakum expands, and you get this incredibly tight waterproof joint. Then you can see on the right, that we’re using it to back a rod to tamp some new lead in there.
Also sheet lead and t-lead. Sheet lead Gus talked about for using for flashing obviously but also for shims. We can get it in different thicknesses so we can adjust the joint or we can pound it down and make it thinner. The t-lead is used for skyward facing joints, set in caulking, and it makes a really nice and, I think, aesthetically pleasing weatherproof joint.
Also, wedge lead which Gus talked about, which we don’t use as much. It’s more for new setting. It’s hard and unless you have a really uniform joint to go back in and try to force that in because some is going to slide in and some is going to be proud. It’s more for setting lead. We don’t use that a lot.
Tamped lead wool and molten pour, as Gus mentioned, you can see the strands of the lead wool. This was taken from a monument that we had to replace. To me, that’s really beautiful. It’s like a Japanese painting or something. What amazes us is how they did all this in one, continuous pour. You don’t see a lot of cold welds between the pours. Obviously, they waste a lot of material. I’m sure it’s not that complicated. I can’t figure it out how they got this uniform pour in that amount of time because you really have to do it fast. It sets up really quickly.
Like any joint that fails, you get biological growth. Dirt gets in there and stuff starts to grow. We can take a section, go back with the wool, and point it. The real trick with the wool, and it takes practice, is that you have compact it. It’s a cold weld. It becomes a solid. You have to get it so it comes almost flush. It can be a little proud and you can trim it, but if you set it as Gus showed in an earlier slide you won’t get that compaction with a new-old lead joint and new wool. It’s just not going to weld together like fresh wool will. You can get away with it. It’s not the ideal, though.
Here is that same monument that’s been … That middle horizontal joint, I believe, is the one that has been repaired. Once it oxidizes, it blends in really nicely. With mortar you can do a lot. You can throw some dirt on it, but mortar always kind of looks a little newer than the old stuff.
This is a Kinmoth monument that we did a couple of years ago. That urn on top had actually had a crack in it and eventually came completely apart. It was obviously a safety concern we had to get on. We used poured lead in this, lead shims, and then lead wood pointing on the base of the pillar. As you can see here, that’s me. I always laugh. I got on YouTube to see people pouring lead just to get tips or pointers or whatever. So many times they’re in short-sleeved shirts. Maybe they have safety glasses. It’s crazy. If you hit just a droplet of moisture it’s going to explode all over you. It’s happened. I think my reaction time is probably broken the record for reaction time because you move really quick when molten lead is exploding on you.
I have the hood, the gloves, my arms are completely covered, everything is covered. It’s common sense. As you can see, this does have a propane tank. You can see at the bottom right is the cast iron pot. It’s a propane-fired little plumber’s pot. You can see I’m doing the pour there. The ladle we have are nice and heavy-duty and they also have a collar on the stem so you can turn it this and it turns in the column and makes it a little safer than trying to maneuver.
Then you see on the top, there’s a little bit of slag there which is impurities that … You can flux it actually. When you melt the lead, you can throw a little wax or people use a lot of different things. It cleans up impurities, brings it up to the top, you skim them off, and get less of the impurities when you pour.
Then this is the bottom of that pillar is the lead wool that was missing and that was then replaced by us. As you can see, it looks like it’s been there for a really long time.
Damming for a vertical joints and anchor joints, what we us is called a Babbitt-Rite. It’s a molding damming clay that will withstand temperatures up to about 9,000 degrees. It’s ideal for lead. It’s a nice moldable, sticky. It makes a great damming material.
This was a rail where we have a rose path at Mount Auburn. I’m not sure why this broke off. There isn’t a lot of jacking there. These are just regular steel plumbing pipes. They have the threads on them and everything. As you can see, it’s a nice inside look at what the joint looks after it’s poured. It’s completely covered around. It’s nice and tight. In the pour before, they didn’t care too much about their material cost because they didn’t dam up the pipe and it just kept running so you have this really cool kind of tongue coming out from the anchor.
This, again, is that Babbitt-Rite damming putty. It’s put around, and this was a little spigot on the top. It’s just poured, then that’s what you get at the end. That’s just all trimmed off and tamped. As Gus said, it oxidizes in different ways. Ideally, and this is what I think is ideal, is you get this nice bluish-gray hue. I think it looks really organic to me. It really compliments and it goes well with the granite. It really blends into the whole monument.
The speaker talked yesterday about lead capping which we’ve done some of. I think it’s tremendously effective. This some we did a few years ago. That overhang is probably a little heavy. You can trim that back so it won’t look as heavy on the monument. It will give it a little bit more of a delicate touch. As the speaker said, the critters love lead. It’s sweet, tastes like strawberries, I’m told. I haven’t tasted it myself. That’s why kids like it, they like strawberries.
I did this cap and it was okay for four years. It was perfect. Then they found it and they went at it. They basically ate that whole thing. This is early on in the gnawing. I used to go around and I would see all the granite curbing we had and all the granite curbing had lead pointing. There was these marks on them, like the scrimmers from the grounds crew, but it didn’t really look like that. I didn’t put it together for a while. That’s what they’re doing. They love it and the gnaw on it. There’s no getting around it.
What I’ve come up with I think is working pretty well is I took B72 and added hot sauce. Then I paint that on to deter them from … You put it around your garden, garlic or hot sauce or something really offensive. I put that on and I haven’t done really any scientific experiments. I guess you should probably reapply it every year or two. It seems to be working for what we’ve done.
The nice thing about lead, too, it can be re-tamped. The lead doesn’t really fail. The stones move and so they’ll eventually work it out of the joint. It can be re-tamped. You don’t get the best joint at the butt, but it’s acceptable.
This is the Shaw monument. This is Robert Gould Shaw who led the 54th Regiment, the first official African-American unit. He died down in South Carolina where he’s buried. They would not let him … They said something really nasty that he should stay with his troops. This is his family. The bronze plaque you see missing there is a plaque to Robert Gould Shaw. He is not there. This was a complete restoration. We recast missing cast iron fence. The ancient marble in the middle there was restored. Then the enclosure was restored.
Then Steve Brown, who is our preservation craftsperson and myself, we put caulking in the joint. You can see the T-lead and then it’s just formed with wooden blocks to work its way in there take up all the irregularities in the stone. You can also see that crimp in there that also had lead around it to secure that and waterproof it. That’s finished. That’s probably before it really oxidized. Once again, when it oxidizes it gets that nice organic feel, a nice bluish-gray. Even with this sandstone it blended in nicely.
One of the more interesting things I ran into is the gentleman. There’s got to better ways. He poured molten lead into his ear. It did not kill him right away. He was in agony for five months and eventually died of lead poisoning. As you can see, they drilled it out of his ear but they didn’t want to get too close to the brain. Why not just take the chance? That was one of the more interesting things that I found. That was in 1908.
Ironically, he was buried in a lead coffin. I’m making that up. I don’t know what he was buried in. This is an image I found of a lead coffin that was unearthed. I’m not sure where it was from. Lead is all over. It’s very versatile and you can see it’s help up really well underground.
Thanks very much.
Lead has traditionally been a widely available, durable, and versatile material used in several different forms in setting and maintaining cemetery memorials. Wedge lead, sheet lead, lead wool and poured, molten, lead were all used at various times at Mount Auburn Cemetery, where countless monuments are set on lead and many of our mausolea are pointed with it. During the 20th century, as alternative setting materials became available and, more recently, the potential health effects of lead exposure became widely understood, lead fell out of favor among monument setters. As use of the material has declined, the skills necessary to restore and maintain historic monuments are becoming more difficult to find. At Mount Auburn Cemetery we have been exploring the advantages of this once prevalent material, and aquiring the techniques to use it effectively and safely. In this presentation we will share a bit of the history of the use of lead at Mount Auburn and discuss our lessons learned over the course of several preservation projects.
David Gallagher is currently employed as the Chief of Conservation at Mount Auburn Cemetery in Cambridge, Massachusetts. David graduated from the Preservation Carpentry Program at North Bennet Street School in Boston in 1995. He was employed by Webb Architectural Preservation from 1995 to 1999, specializing in all aspects of the preservation of 18th and early 19th century homes. In the summer of 2000 he studied with Tim Meek of Scotland, a noted practitioner in use of traditional lime mortars. After two years as sole proprietor of Gallagher Historical Restoration, he joined Mount Auburn Cemetery. David was a 2002 Quinque Fellow, studying stone conservation practices with Historic Scotland as well as private stone conservators. He has studied with Nick Micros, a noted sculptor, preservation mason and a 2006 Guggenheim Fellow. He has practiced preservation craftsmanship for 20 years, while focusing on the conservation of stone monuments and sculpture the last 12 years.
Gus Fraser serves as Director of Preservation and Facilities at Mount Auburn Cemetery, a National Historic Landmark located in Cambridge, Massachusetts. He has a B.A. from Duke University and an M.A. in Historic Preservation from Boston University. He is in his ninth year on the staff of Mount Auburn and has over twenty years experience in the preservation, restoration and maintenance of historic structures and sites. Prior to coming to Mount Auburn he operated his own business providing high quality historic preservation services to house museums and private homeowners. At Mount Auburn he directs the preservation of the Cemetery’s unique and historically significant collection of monuments, mausolea, and cast iron fences. He also works with contractors, architects and engineers in overseeing the repair, retrofit and restoration of the Cemetery’s two 19th century chapels and other historic structures.