A Century of Earthen Architectural Conservation in American Southwest National Parks

This presentation is part of A Century of Design in the Parks: Preserving the Built Environment in National and State Parks, June 21-23, 2016, Santa Fe, New Mexico.

Abstract and Presenter’s Bio

Jake Barrow, Cornerstone Community Partnerships

Jake Barrow: Thanks to NCPTT for holding this and getting us altogether and allowing me to speak. I’m going to take a different approach from Frank, and be repeating some things about this because Tumacácori is a fabulous laboratory, and so I’m going to get into that. I just want to say that Hugh Miller was talking about in the ’70s, when Jim Askins and all this business about the exhibit specialist started, and I came in as an exhibit specialist. My whole career was an exhibit specialist, and so that’s basically a practitioner. The term is kind of hard to understand, but my career in the Park Service was hands-on and project management out there, and so the point of view that I’m taking about this subject is from that point of view.

We’re talking about the earthen architecture sites, and particularly adobe and the pre-Colombian sites. The sites I’m going to focus on there are Fort Union, Pecos, Casa Grande of course, Tumacácori. I might get around to mentioning Fort Buoy, and Fort Davis, and I’m not going to get down here. These are sites in which earthen architecture is predominant. As Frank said, things did start at Casa Grande and I’m going to try not to repeat too much of what he said. Casa Grande is a puddled earth, as distinguished from adobe brick, and so that’s a very important distinction. It’s a remarkable place that was constructed sometime around 1200 A.D. and abandoned around 1400 or so.

The thing that always struck me when I went to work at Casa Grande was what happened between 1400 and 1891? How did this place survive in this condition that it’s in, over here? As we get into this we discover a few things about it. We think about this, of course, this is all not National Park Service but General Land’s Office was in charge of all this kind of stuff up until 1916. In 1891, when this was set aside … Excuse me, 1889, it was first recognized in a Congress declaration to repair and protect the ruin of Casa Grande. It’s 127 years ago. If it hadn’t been for this hundredth anniversary, I would’ve titled this paper 127 Years of Earth and Architecture Preservation.

In any case, when in 1891, Congress sent $2,000 to this project. This is remarkable at the beginning to see that, and they had six things on their mind to do down there. To put up a protective fence, to get a site management custodian, to clean the site, underpin basil erosion, to cap exposed walls, to reinforce freestanding walls, and to develop a sheltering roof plan for the structure.

Then you can see some of this in this lower picture here, where work is already gotten underway. It’s a pretty heavy-handed treatment of brick and cement mortar around here. Construction of doorways and infills and things. Even today, this stuff is still in place and it’s maybe there’s a question about what the effect of that is. The major impact of the site comes in when the shelter goes up.

Casa Grande

The first shelter was in 1902. This barn-like shelter that went up. Then in 1932, this contest to build a new shelter over the ruin, and of course, won by Frederick Law Olmsted Jr., we talked about him yesterday here in the meeting. This is, of course, the famous, famous shelter that you hear worldwide, please, let’s don’t have a shelter like Casa Grande. You hear this all across the National Park Service. Whenever in the Southwest region, where I was working in the division of conservation, we’d go out to a park and recommend, “Could you consider a shelter over this ruin?” The first thing the superintendent would say, “Not like Casa Grande.”

It was really interesting to me. It’s been interesting to me over my career how this has engendered so much negativity. When you actually go on-site and start to confront the monument itself, the structure tends to disappear, believe it or not, if you have never been there. I think it’s here to stay anyway. It’s a national historic feature in its own right. There’s nothing going to happen to that.

Of course, Frank “Boss” Pinkley was behind all of this. One of his first job was for the General Land’s Office at Casa Grande, and was responsible for taking care of all of this. In 1910, he made this quote, “from which there seems to be no practical method to protect the greater part of them,” speaking about the walls at Casa Grande.

Even early on, you know, the sense was that even with this shelter that with wind and rain and whatnot, this earthen architecture structure was going to be very difficult to preserve. Then I want to move on right now back up to Tumacácori, and Frank was very eloquently talked about the planning issues there. I’m going to talk a little bit about some of the material things and look at this. When Boss Pinkley went up here, and I’d like to see the contrast between Casa Grande and Tumacácori and what he did, because he’d been a participant in the shelter at Casa Grande but he had no intention of thinking about that in this location, here. I’m not sure of all of what the reasoning was, but of course as Frank said, the main thing done was to reconstruct this and then reconstruct the roof over the nave, which ostensibly really did save the building.


The other thing that to think about here about preservation too is that, luckily the building was encased in a lime plaster exterior. That’s a great preservative for adobe brick. Now the thing is, is that as a ruin, it had this kind of disrupted surface in a lot of places. I think it’s really interesting, Frank talked about this, there’s a lot to think about here about where to stop and where to start with this repair.

We know, over the hundred years or so, not quite, that there’s been a lot of re-plastering on Tumacácori and lime plaster. Very sympathetic, and always with a sense of trying to maintain this, kind of partial, restored effect. A lot of things in the literature about that, and to think about this being done in the 1920s, a little bit advanced ahead of that Athens charter in 1933 or whenever it was, that got into all of this. It’s interesting to me to think that some of these thoughts were at work then.

Just to show another aspect of that and I won’t go into it. Frank mentioned about Southwest monuments, and I think that’s a very important step in the Park Service development of management of sites and ruin sites and archeological sites in the Southwest. Frank Boss Pinkley certainly was a manager who coalesced a whole program around that, for sure to get funds out of Washington to come down and treat these things, because ruins in the Park Service have been a real, real stepchild for getting funding out of the Washington office. It’s been a problem and Pinkley understood that.

Now in 1930, we start to see the Washington DC, the Washington office, issued the following notice, “The National Park Service is seeking means to protecting Pueblo ruins from weathering.” Well they’re including, that’s a name for all the ruins in the Southwest, including Tumacácori. “The ideal solution would be a transparent, waterproof coating which could be sprayed on the walls, but no suitable product has been found and the Service announced today it would welcome suggestions for a substitute.” Here in 1930, the Washington office is putting out a call to find some treatments for these adobe walls, because now I don’t have to explain to anybody in this room that adobe’s made of earth … you put it out in the weather, guess what? It’s a downhill slide. So, in response to this, the Standard World Corp. Company, Standard World Corporation in 1932, came up with something called Soil Bitumen 1, an emulsified asphalt, and it started to find some use, surrounding some sites, some experimental use.

Stanford University responded with an experimental vinyl resin. They labeled it NPSX, began to be applied in 1935. It was applied to the exterior, interior nave surfaces of Tumacácori. Unfortunately in my records in looking at this, I didn’t really find hard data to say exactly what, where, how all these things were done. But, as the years went by and by 1940, and probably Pinkley had something to do with this meeting, I don’t know if he had tended it or not, but there was a meeting in Santa Fe here at the headquarters we were at last night, of managers from Washington and Pinkley, or whoever. I think Pinkley was there. The basic deficient, and this came out of this meeting, a several days’ meeting, “The basic deficiency is material. It is highly probably that superior methods of application will quickly follow the development of suitable materials….Existing stabilization measures are founded almost entirely upon the use of native soils, cement mortar as capping, cement mortar and soil mortar masonry and particularly at Chaco Canyon, native soil stabilized with bitumen.”

“A single attempt to apply modern plastics was made between 1933 and 1935 which consisted largely of experimental work and which failing to recognize the physics and mechanics inherent in the problem, resulted in little, if any positive value.” And in concluding this little section “[It] must be supplemented by materials of different characteristics which probably will be found only in the developments of industrial chemistry. The resins, and silicon ester in particular, appear to offer hope of eventual solution.”

Fascinating that it started. Also, I think it’s interesting that the silicon ester was mentioned that early, because it wasn’t until sometime in the late ’70 or ’80s, I think it’s Giacomo Chiari that actually did a scientific thing with silicon ester, and showed [inaudible] where this really works to stabilize adobe in a certain way. Let’s say as a conservation surface treatment.

Also, during the ’40s and during this war-time period in the ’40s, the use of what became known as soil cement in the Southwest was spreading around. This is basically just portland cement mixed with soil as a stabilizer. Of course during the war not a whole lot happened. This is sort of distinguished as a treatment from a spray-on treatment, like we will see in a moment.

Whoops. Just as an aside, I think Tumacácori’s such a rich site, and so much to find there. This cocciopesto which is a Greco Roman, 400 B.C. lime stabilized coating made with crushed ceramic, can be found at Tumacácori. It’s probably the only place in the United States where you can find it. I just thought it was fascinating. Doesn’t have much to do with the adobe.

In 1946, a survey at Tumacácori, again, identified some issues. Adobe basal deterioration, apparent widening of cracks, plaster deterioration at the mission, and painted surfaces were also survey and looked at. This project represents the first application of art conservation methods towards architectural fabric, within a ruins context in the Southwest, at least from my reading. In this first effort to work on those interior walls, they were using, I think polyvinyl acetate.

Jumping ahead quite a bit, in 1971 the University of Arizona Soil Science, was tasked with researching moisture problems at the walls of Tumacácori. Rather than simply continuing to treat a symptom, an effort to understand the cause of the problem was behind this request. I think this is interesting, where it’s beginning to look at holistically at the system of walls, the surfaces, the plasters and the whole nine yards. What’s the source of the moisture? What’s the quantity? How does it move in the materials? What can be done to address the problem?

By 1975, the fundamentals of a new approach, including laboratory material analysis, recognition of the process of deterioration, monitoring your rate of change, increase levels of documentation, multi-disciplinary team approach, and a critical review was being put into place. They planned a merge which included a more judicious application of conservation materials, which could be scientifically evaluated through monitoring. This was a time when acryloid B-72 was used down there, at Casa Grande. Of course, all of this sort of ends with the work that Tony Crosby did, of the idea of reattaching plasters to adobe. Which came to be quite an interesting sort of problem.

In 1955, the preservation workers at both Casa Grande and Tumacácori were using Daracone, stepping back a little bit here, an industrial silicone-based, waterproofing product. A spray-on product. These spray-on products kept cropping up over and over again during the ’50s and into the ’60s, as being a cure-all for the adobe, with the hope that you could come out and get your sprayer with some materials and in this case the Daracone and various silicone products, and spray them and have a very quick job of it. They had a very positive response for about a month or two, until the rains hit. None of this ever lasted more than a year. It became really, really hopeless failures, just about continued.

About that time in the late ’60s, another product came on the market, Daraweld C it was known as, it’s still in use to some extent. It began to replace this because it could not only be sprayed on the adobe but also inter-mixed with earthen materials. I’m not going to talk about Chaco, Mesa Verde, and all these other sites, but all of these was of the same problem. Trying to stabilize earthen materials, whether it be mortar or the adobe.

Pecos National Historical park

Jumping ahead, Pecos National Historical Park was established in 1965. Pecos National Monument, at the time. It’s an extensive adobe ruin, which is a Spanish colonial mission structure, set on top of a pre-Columbian pueblo, with a convento. All but out of adobe, and of course a lot of stone foundations there and stone bases. The original pueblo is stone and earth. Of course all the same problems here too, right way. In the ’60s, this energy is really underway. The archeologists in 1974 wrote, “But I think that the basic problem then and now, even remains the same. We do not yet know how to stabilize and preserve exposed adobe earthen walls. A lot of people in and out of the Park Service have been or are working on the problem, and progress is being made, but we have a long way to go.” So I think at Pecos, the Pecos history is quite interesting in that, in capsulation … Whoops. Whoops.

In capsulation of the original historic walls became the modus operandi there. It developed in a series of experimental applications until where it was decided that the best treatment was to use an adobe, the near brick, to encapsulate the historic walls. Over time the mixture of those adobe bricks became modified a certain extent. Most recently with the EC 330 Rhoplex, an acrylic emulsion, I’ll talk about that in a minute, which was a competitor to Daraweld C and it’s continued to today. In my work, I’m actually involved out there now. We have a couple of little test walls out there because it’s really interesting to try to understand exactly what’s happening behind those acrylic-modified veneer walls at Pecos. The experimentation is still underway. I’m working with VT program and a little study out there with the park.

Jumping over to another example that is completely different but extremely interesting. I don’t know if Jerry Rogers is here, but Jerry Rogers got his start over at Fort Davis which is a fabulous earthen architecture site, a nineteenth century fort. The thing that happened at Fort Davis was that, the ruins that were found that when it became a park I think in 1965 or ’56, I’m not sure, in any case, what we find there is that partial ruins, a lot of pieces were intact. So they made this decision when they first started at Fort Davis, that if you had approximately 60% of the building intact, partial restoration would follow. Fix the roof, put back the porch, stabilize the walls, but restrained. No windows, no doors, very limited. Built sections like this were left in ruins. So they went around the fort and did this.

It’s remarkable the preservation at Fort Davis because the interior of these structures have these great paints from the 19th century. Original plasters and paints from the army period. We have to thank Jerry and his team who made this decision. It’s an interesting site. There’s not a whole lot … What happens there with these ruins is they get soil cement caps on them and it’s pretty much as simple as that.

Let’s see. A couple of more images. This is another interesting thing that happened and this all this history. In 1974, again, the Washington office weighed in in all of this. Quote, “We have observed the use of many modern materials in the restoration and maintenance of our historic structures which have questionable value, and which in many case do permanent damage.” This is in direct reference to the misuse of cement which became a big discovery in the ’70s. The wrong cement mortar and all this. Of course cement, and soil cements and cement was ubiquitous in the Southwest. So, in a response to this in the Southwest, I’m not sure exactly who’s behind this, but in 1975 the Southwest Region hired Dr. Denny Fenn from the University of Arizona, a soil scientist, to join the Park Service and work on these issues around how to best stabilize adobe.

Dr. Fenn spent three years working on this and his primary idea was to construct test walls around in different locations. Test walls had had a little history already. He made it very scientific and very controlled about the types of chemicals to be used. Of course, the Daraweld was used and these other silicones were used. As well as the EC 330 was introduced. And around, you know he had these test walls. As usual with the Park Service, just about the time when success, and he started to note, and he wrote a report about, “well, the Daraweld works, the EC 300 worked…” Well, they terminated the program and he went back to the university. That was it. No more scientific study.

Here we have at Chaco, this great wall. I was in the Park Service at the time, had this great trip in 2004 where some of us got together and got Dr. Denny, to come over and meet us, and let’s take a look at those walls, are still there. They’re still there today I’m sure. So let’s do a little evaluation. Sure enough he had his notes an everything, and those acrylic emulsions and whatnot were still in fairly good condition after that twenty year period. Of course in a situation where they’re in wall sections like this, we’ve learned that you can almost put anything in there really. But the application of these two chemicals, the Daraweld and the Rhoplex, took off like wildfire around the Southwest. I mean, everybody started using one or the other of them, as some sort of an add mixture in either their adobe or their mortar. We see it as ubiquitous.

Finally, at Fort Union which is right near here. About one hundred miles up in the direction of Vegas. In 1956 Fort Union came into the national monument … came into the Park Service. It’s some 56 structures, 150 thousand square of un-roofed walls. It’s located in this high plain of New Mexico. To quote from the nineenth century record of some of those soldiers who were there, maybe a soldier’s wife, “Indeed, from the moment they were completed until their abandonment in 1891, the fort’s adobe structures were in an almost constant state of unremitting deterioration.” Well, you have to stop a minute and think, “Gee, did the Park Service know what they were getting into when they signed on to take care of all this stuff?” Really, it’s like a hopeless task, like the Myth of Sisyphus or something.

But this Fort Union has this great history about what happened there and what was done. Between 1956 and 1958, excavations were done, site-clearing and some structural stabilization, which sometimes amounted to braces, basal repairs of walls. Things like these chimneys back here were filled up with concrete and all kind of things like that. In 1959 to ’62, capping with sol cement adobes and spraying with silicone mortar repellent was the treatment of choice. So this is very important, in 1962, they went around the fort and they put sol cement caps everywhere, on top. And they sprayed all the walls with this silicone stuff that was being used everywhere else. We saw pictures of spray.

This continued, the applying. With the addition of applying some soil cement shelter coats in some areas. By 1981, there were some noted and recognized failures with this wall treatment. And so at the time, all use of any chemical cements were discontinued at Fort Union. I’m not exactly sure who’s behind it, probably Dave Battle who was down here running divisional conservations, behind that whole deal. Then it was decided, OK, unamended plasters. That’s what you’re going to do, and they did. From 1981 until about 1996. The staff at Fort Union mud-plastered these walls. I have to hand it to them. It didn’t work out really well. It was certainly better than the previous treatment, but they couldn’t keep after it. Too much work, not enough money. Not enough staff. It couldn’t happen.

This is where I came on the scene. In 1991, I met Frank Matero and we started to launch a partnership and a cooperative agreement with the Graduate School of Historic Preservation here at UPenn. Fort Union was one of the first sites to go to. To look at, first of all, some very material scientific things about how these plasters that are still remnant there and can stay in place. It began to grow into a larger concept of preservation, preservation strategies, what can happen at Fort Union. It resulted in a wonderful collaboration which I know is still underway. Frank is now gone back to work at Fort Union to look at these things.

Out of that work, several things emerged, great credit to some of the students particularly Bob Parsler and Neil Oliver who worked on this, graduates of Penn, was that in twenty, thirty years later, these cement caps were shown to be excellent treatments. If it wasn’t for those, the walls would have been down. But at that time, when the Penn students did the survey, they were at the end of their life. They needed something, had to happen, so the decision had to be made. What about those sol cement caps.

I didn’t show a picture of Fort Bowie but Fort Bowie went through the same thing. Cement caps everywhere and in 1970 when this directive came out of the Washington office, the person in-charge down there decided, “We got to get rid of those sol cement caps that’s destroying the walls.” Took them all off and started with some other kind of treatment a few years later, in desperation, when the walls started to come down with the sol cement cap. So in 2001, a lot of other things happened here but one fundamentally very important thing was the sol cement caps got put back on there and they’re performing quite well after ten, twelve years at this point.

Just to make one final comment about the association with UPenn, coming back to Casa Grande, this is the wonderful thesis work that Elisa Del Bono did, where they looked at the materials of the Casa Grande and what was really happening at the surface of these materials. What she showed was, is that the molecular carbonates because it’s a caliche type of material, it’s a very wonderful material, were migrating in evaporation sequences of just humidity, to the surface, and case-hardening the surface. It was like, wait a minute everybody. Don’t touch it. Don’t touch it. Because it’s weakening in its depth, but strengthening on the surface, so it’s case-hardening. Leave it alone. As far as I know, there’s no treatment program being recommended for Casa Grande.

I have to say, Frank and I were talking about this last night, and he was using this. He would say, “These treatments with adobe, it’s sort of like shifting the deck chairs around the Titanic.” I’m quoting him. “Shifting the deck … ” I went home thinking, “That’s exactly right.” Except not completely, because I think we’re making great strides and great progress. Where I work at Cornerstones we use totally unamended plasters. We have plasters at the Sammy Hill Church here that are five, six years old that are just as good as we put them on five years ago. So, we go to extra trouble to do that. I’m out in the park sometimes talking about, “Let’s don’t forget about unamended earthen materials. There’s a lot of potential there.”

So for that, thank you.

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