This lecture is part of the 2009 Nationwide Cemetery Preservation Summit
Preservation Issues of Wooden Grave Markers and Other Wooden Artifacts by Ronald W. Anthony and Kimberly D. Dugan
Good afternoon. Thank you for sticking with me for the final presentation of the afternoon. Now for something completely different. Wood is not stone as I have found out from sitting here listening to some of these presentations today. I’m with Anthony and Associates, we’re a consulting firm for wood technologies, wood structures. We were lucky enough to get involved in a project with the city of Aspen and it was funded through NCPPT to address the preservation needs of wooden artifacts in cemeteries. Surprisingly, or perhaps not surprisingly, there really isn’t a lot of information out there on how to preserve these fragile artifacts. I’m going to use the words artifacts and grave markers interchangeably but I’m really speaking about anything made of wood that might be in your cemetery that might be old. If you want to keep around old wood that includes grave enclosures, grave curbs, grave cribs, grave houses, perimeter fences, plaque fences, that sort of thing, if I say the word wooden artifact or grave marker I’m referring to all of those things.
We produced the manual and it’s available for free for download on the NCPTT website. I have that complete address at the end of the presentation if you’re interested.
Preservation issues. What we’re going to to talk about here is the ways to identify and assess various forms of wood deterioration. That includes weathering processes, damage from moisture, wood decay, fungi, moss and lichens, and insect damage. There’s also mechanical damage as you all are very well aware of with lawn mowers and weed trimmers. That sort of thing, because of time issues, I’m not going to talk about, but that does exist for wood as well. Because we all know people who take care of cemeteries don’t tend to have a lot of money, cemeteries don’t usually have huge budgets, the most important things I’m going to talk about are the low cost, low maintenance options such as moisture management and vegetation management to help extend the service life of wooded artifacts. Third and last I’m going to talk about repair options and the challenges of replacing and repairing in kind, methods that definitely don’t work, and some possible alternative solutions. If any of you guys have had success with repairs to wooded artifact, please come talk to me afterward, because I would love to hear about that.
Things that damage wood. If any of you guys have wood, wooden decks or wooden siding on your houses you know that wood has to say dry. Moisture is the bane of wood. Once wood gets wet it shrinks and swells, splits, warps, cracks, does all these kinds of things that you don’t want it to do. That’s because, as hopefully all of us knows, comes from trees. As a living thing trees need to pull moisture up from the roots and bring nutrients down from the leaves so it was designed as a living tissue to allow moisture to permeate it. Once you cut that wood into lumber it still has those properties. If you place a piece of wood in the ground it’s trying to pick moisture up from the ground. There’s nothing you can do to stop that. If you try to do anything to stop that you’re going to cause some problems in the ground, within below the ground level that accelerate the deterioration process.
What you’re looking at here is call stove piping. This is the top of a grave enclosure fence post and it was cut flat and moisture was allowed to sit on the top here. When moisture gets to a certain level moisture content of wood, wood decay fungi becomes active. What they’ve done is eaten a hole in the top of this post. Now, to complicate the issue we’ve got this debris that’s fallen in there, which further inhibits moisture evaporation. You’re creating an environment that’s just accelerating the deterioration process.
Another thing that happens to wood exposed outdoors is weathering. Now, unlike other type of deterioration mechanisms weathering is actually not that big of a deal in the wood preservation world. Yes, it does erode the surface. It tends to erode the early wood first because that wood grows fairly quickly and the cells are not as dense. It leaves these ridges that you can see very clearly here. It can erode anything that’s written on the marker itself. That’s the primary concern itself but as far as the actual long term impact of weathering, it takes about a quarter of an inch off the marker every hundred years. When you’re talking about deterioration rates that’s not really a big deal for us. A lot of people actually like the look of weathered wood.
This however is a problem. There’s all kinds of wood decay fungi, there’s brown rot, white rot, soft rot, dry rot. It’s kind of a Dr. Seuss collection of rots. Any of them are bad. This poor marker here I’m lifting up is basically half eaten away by decay fungi. The second image here is a close up of what we call white-cottony fungal bodies. If you see that you have a big problem. The next one down here is this lovely mushroom that we found growing on a plinth type wooden artifact. The whole handle, sorry, whole handle here for scale
How do I go back?
A new one
Can you go all the way back to the?
It’s going forward. You guys can get a fast forward of the presentation.
There we go. Thank you so much. It’s completely the opposite way that I was doing it.
The awl handle is an inch and a half for scale so it’s quite a large specimen.
Molds and mildews. You actually see this quite commonly in buildings, in basements, on wooden floor joists, and interestingly enough, this is the back of a painted marker. You can see the green staining. It’s a surface phenomenon for wood. It doesn’t damage the wood itself. It can be easily removed, but what it is an indication of is a potential moisture problem. It means that the air circulation around this piece is not very good and that there’s a high relative humidity in the piece, or high moisture content in the piece and so you need to be aware that this is an indication of a potential problem.
Lichens, I found out, are rather contentious I guess in the stone preservation world but I didn’t know. From a wood preservation stand point they do not harm the wood. Yes, they do release an enzyme that may break down the wood over time but the rate of the actions is so slow given the lifetime of wooden artifacts that we don’t recommend removing them. If fact a lot of the lichen are so firmly anchored to the sub-straight that you’re going to damage the wood if you try to take them off so, basically we recommend leaving them alone unless they can be easily removed.
Moss on the other hand is a different story. Moss is a non-vascular plant and it is not damaging to the wooden artifact itself, however moss needs nearly constant and very high levels of moisture to exist. If you see moss growing you know that you have a moisture problem. The other thing that moss does is it acts like a sponge. It holds moisture up against the wooden artifact and that just encourage wood decay fungi to grow.
There are many type of wood-boring insects that can damage wooden artifacts. I think that mostly what everyone here is concerned about is subterranean termites. They might be forester termites or just regular subterranean termites. The other wood-boring insects, with the exception of carpenter ants, don’t generally do severe structural damage to wooden artifacts. You can see in the upper image the marker that we removed from the ground. There’s this great big void in the middle that’s been eaten away by termites. The rectangle shows a close up of these little guys. They’re very happy and they’re eating a little bit of this poor marker.
What do we do about it and how do we assess what damage is being done? Well, you need a few simple tools. It’s interesting, I was sitting in here listening to the ground penetrating radar and the electro spectrometer, all these wonderful fancy expensive tools, and as wood consultants we have fancy expensive tools too. We absolutely do and we love to use them. There’s nothing wrong with them. They provide a lot of really good data when you need them but, we’re focusing on the things that individuals, lay people can do without any special training to help extend the service life of their wooden artifacts. For that you need to be able to see and you need something you can poke other things with, and you need a moisture reader. We’ll talk about those other things in a minute.
Visual inspection is the first step to assessing what you have. Here’s me, I’m in Aspen. It was a lovely day, and I was looking at this poor artifact again half eaten away by wood decay. I had my trusty clipboard. Any good visual inspection includes mapping where something is, writing down any identifying features, the size, the shape, and then assessing the deterioration. Does it look wet? Does it feel wet? Does the wood crumble when I touch it? Are there bugs? Is there bore holes from insects? Can I see frays or fecal pellets or something that indicates insects are around? You do a quick assessment of all those things and you write it down. As we all know, wood is not the most long lasting of materials and it may be gone in ten years.
Probing and moisture content. The next step is to probe the wood. Now, one of the things you want to make sure is that you’re not poking the wood with a really sharp implement. I’m sure we’ve all gone to the hospital and we’ve had our blood drawn or gotten a shot. These are very sharp needles. Imagine trying to get your blood drawn with something like a knitting needle. Right? It would be excruciatingly painful. We want to do the exact opposite with wood. We don’t want to penetrate healthy wood fibers. If we have a sharp implement it’s going to go right through the good wood tissue. It’s not going to tell us the condition of the wood on the inside. We want to have a blunt instrument, an old screw driver, an ice pick, or an all with a rounded tip. You want to probe in areas only where you know deterioration would exist so, at or below the ground line, not across the face of it where it’s been written or inscribed, it would be a bad idea, and at connections. If you’re looking at grave enclosures you want to make sure if moisture’s been collecting where two pieces of wood meet.
The next tool that you need is a moisture meter. Now what you’re seeing here is a moisture meter with pin probes. It’s call a resistance meter. It does leave two holes in the marker so you don’t want to use it all over the place, you want to use it judiciously at the ground line because that’s the most significant area. That’s where most deterioration is going to occur. If you want to see how well the piece is evaluating moisture you can test above at the top. You can see in the image here this reading, I don’t know if you can see it, says ten percent. That’s incredibly low moisture content to take a reading at the ground line and get ten percent. Up at the top it reads six percent.
So this marker, for being a hundred years old, is in exceptionally good shape. There are other types of moisture meters called capacitance meters, I think, that do not have pin probes. You can use those in cases where you don’t want to put holes in the wood. They have a limited depth that they can measure the moisture to. It’s usually about a half inch, it depends on the model. It’s great for thinner elements like these grave markers, but for larger elements like fence posts, four by fours, you’re going to need something with a pin probe.
We know now that we have some problems with our wood in our cemeteries, so what do we do about it? This kind of hearkens back to the recent presentations we’ve seen this afternoon, we need to control moisture as much as possible. We need to have good vegetation management. Then I’d like to talk a little bit about borate rods and coatings. This is not a good idea. Having a sprinkler head right next to a wooden marker is a recipe for wood rot. IF you have an irrigation system in your cemetery you need to assess the spray pattern and remove or relocate any sprinklers that might be nearby. The same goes with watering spigots. You can water by hand near these guys but any amount of water is going to contribute to faster decay.
Vegetation management. This is a cemetery. That’s my boss, Ron, looking for wooden markers with a rake. Probably not the way you want to go about your assessment, and it just shows you it’s really important to have good vegetation management. It should be hand trimmed around each marker if possible. This is a cemetery in Aspen and they simply don’t have the funds to maintain the ground. This is a big problem because all this vegetation is, number one, inhibiting sunlight from reaching these markers, it’s keeping the moisture from evaporating as quickly, it’s encouraging a collection of dew and when this foliage dies back in the fall it accumulates at the base of the markers and contributes to the decay of the base at the ground line of these markers.
What can we do about it other than that? Borate rods work exceptionally well for a lot of homes and for exposed rafter tail ends. They’re used in wood preservation fairly successfully. I would love to tell you that they work great in cemetery applications, however I have not found anyone who actually uses them in a cemetery. If anybody does, wonderful. I think they’re wonderful tools. What they are is a low level toxicity fungicide and insecticide. You drill a hole in the piece, insert the rod, it’s supposed to last three to ten years depending on the amount of moisture in the wood. It only works when the wood gets wet. When the wood is wet the rods dissolve, the borates penetrate the wood and protect it from insects and fungus. They have plastic claps that they sell so that as part of a regular maintenance program you can install these rods, put a plastic cap on them, come back five years later, undo the plastic cap, insert a new rod, put the marker back in the ground and you’re good to go. This is a way to help extend the service life of wooden artifacts without doing too much destruction to the historic fabric.
Coatings. I would love to tell you that there’s a coating out there that could withstand the forces of UV degradation and weathering. Unfortunately, there isn’t. As any of you know who have a deck and you have stained that deck and sealed that deck every summer, you have to maintain coatings. They’re not a great way to go about establishing a low cost maintenance plan for your wooden artifacts. This was coated with something like a varnish which has no UV resistance. You can see that the coating has yellowed. The bond between the wood and the coating has failed and the coating has failed. It’s a completely inappropriate material for wooden artifacts. If your artifact isn’t coated, leave it uncoated.
This is a cemetery in Cripple Creek Colorado where they were lucky enough to have a cemetery maintenance budget and they have someone hired on staff full time to go around and maintain their artifacts. They painted them every year and they repaired and replaced them as they failed the elements as they went. In terms of preservation of the materials, they did a fairly good job. Not everybody appreciated the look of freshly painted wood but it does protect the wood above ground from UV exposure and moisture penetration. No coating you put on wood is going to protect the wood below ground and that’s where most of the deterioration happens, but in terms of protecting wood above ground and if you have already been painted or were historically documented to be painted, paint is a perfectly good option if you’re willing to maintain, and you have the budget to do that.
This is just another view of that cemetery and you see that they do a very good job of keeping the vegetation down, of maintaining and replacing elements as the fail and coating them. It’s a little bit of a different look from this cemetery where clearly no one has taken care of it, and has no coatings, and all four fence posts have failed. The only thing that’s keeping it up is probably gravity at this point.
Repairs. There should be a good in here but there really isn’t. If anybody has some suggestions please let me know. What you’re looking at here is the base of a marker that has been repaired in a traditional wood repair fashion that works exceptionally well for log ends for log homes and exposed rafter tails, which is epoxy with wooden dowels. It’s a very common wood repair. It’s used all the time very successfully. It didn’t work here. Why is that? Well, it has to do with the moisture wicking properties of wood. You put wood in the ground and you have a waterproof membrane in between the cells. Everything that’s below that membrane the moisture’s going to stop and it’s going to sit there and it’s going to deteriorate the wood below the ground. Everything above the ground is not going to get wet but it’s also going to fall down when the base falls down. When the base deteriorates.
This marker was problem a hundred and fifty years old. It stood for a hundred and fifty years before it failed. I met a wonderful man that did these repairs in North Carolina in 2000 and he brought me back in 2008 how they did, and in eight years all of his repairs have failed. We can say for certainty epoxy is probably not the way to go.
Alternatives. So what are our alternatives if we know that the standard repair methods for wood don’t work, putting wood back into the ground is not a bright idea because the wood in the ground is going to deteriorate but we want to adhere to as closely as possible to the Secretary of Interior’s standards? This is a beautiful cemetery near Victor Colorado and we see this beautiful wrought iron plot enclosure on one side. On the other side it’s a forlorn, in much need of repair, wooden grave enclosure. In between is a grave enclosure made of PVC. It slightly alters the historic visual relationship between the artifacts and the cemetery, and it’s probably not what I mean when I say alternative materials. Not the way we want to go, but yes it will last a very long time.
From the Secretary of the Interior standards historic preservation this repair is hideous. From a wood preservation standpoint it’s genius. It solves the problem. The wood is no longer in contact with the ground. Moisture cannot wake up. Wood decay fungi cannot get in there. Insects even will have a tougher time getting in there if there were any termites in Victor Colorado, but there aren’t. It solves the problem. It saved the historic fabric. Are there things they could have done differently? You bet. They have the steel channel here that, had they had more time and money, they could have drilled a hole through the center of this fence post and installed this on the inside and they wouldn’t need the rocks. It would have had much less visual aspects. In terms of thinking of alternatives for wooden markers and wooden artifacts you have to sort of step outside the traditional box of replacing in kind, because we know that those repairs don’t last. It’s something that you have to philosophically agree with or disagree with or negotiate with in order to make the right decisions for your cemetery.
I just want to say thank you to the NCPPT and the city of Aspen for helping us with this project.
Wooden artifacts in cemeteries are often overlooked as significant pieces of our cultural heritage and are typically dismissed as impermanent, and unsalvageable, objects. These artifacts include head and foot markers, crosses, plaques, sculptures, grave curbs, grave fences, grave houses, and plot enclosures, as well as historic perimeter fences. Two primary factors have led to poor decisions regarding wooden artifacts:
- The general lack of readily accessible information on the conditions and conservation needs of wooden artifacts. Since wooden artifacts have characteristics and properties that differ from stone and metal monuments, it is important to have a basic understanding of wood as a material, wood deterioration, and available treatment options for artifact preservation. Additionally, unlike wood used in the construction of a house or building that is typically periodically maintained, wooden artifacts are continuously exposed to ultraviolet light, precipitation, freeze/thaw action, and exfoliation processes, all of which hasten the wood deterioration process.
- The expense of regular maintenance and/or treatment programs. Cemetery stewards must often act to preserve fragile wooden artifacts with limited financial resources, placing expensive or high-maintenance treatments outside the range of realistic preservation options. However, with some basic management practices, the service-life of many wooden artifacts can be extended with little financial cost.
This presentation, targeted towards lay and professional practitioners, provides a foundation for understanding wood and identifying the various mechanisms of deterioration for wooden artifacts. The presentation will include a discussion of:
- Some of the physical properties of wood and how wood behaves when exposed to exterior environmental conditions.
- Methods to identify and assess the various forms of wood deterioration such as weathering processes, moisture, wood decay fungi, moss and lichens, insect damage, and mechanical damage that can occur within wood exposed to the elements.
- Low-cost, low-maintenance options, such as water and vegetation management, for extending the life of wooden cemetery artifacts.
- Repair options: the challenges of replacing or repairing in-kind, methods that do not work, and possible alternative solutions.
Kim Dugan, Preservation Specialist, has a M.A. in Anthropology with an emphasis in Historic Archaeology from Colorado State University. She has also taken coursework in Construction Management and Architecture with an emphasis in Historic Preservation. Her experience in cultural resource management and historic preservation project management extends over a decade. She focuses on documentation and research needs as well as new products and technologies for wood preservation.
Ron Anthony, Wood Scientist for Anthony & Associates, Inc. received a Master of Science degree in Wood Science and a Bachelor of Science degree in Wood Science and Technology from Colorado State University. His research and consulting activities have focused on developing a better understanding of how wood interacts with other materials and performs over time. In 2002, he received the James Marston Fitch Foundation Grant for his approach to evaluating wood in historic buildings.