Posts Tagged preservation
I encourage the next generation of future masons to always look for opportunities to embrace mentors in our trade. And to the older masons I say make a difference in the world of a young person looking for a trade and openly share your professional experience in masonry knowledge in the preservation of important historic architecture. We each bring to the table a skill set that can, and will, make a difference – if, or course, we are given the chance and awarded the projects we seek to secure.
Many of you may not know about my background and experience in masonry preservation – so I will provide you with just a brief overview of how I ended up where I am today with the title of: “Historic Masonry Preservation Specialist” I grew up in the masonry construction business working for my father, uncles, and grandfather in a family owned business located in Toledo, Ohio. This opportunity to be birthed into a family of working brick and stonemasons was not by choice but to keep me out of trouble in my teenage years. And yes, it did work. There is something about carrying brick and stone, building scaffolding, mixing mortar, and cleaning out the toolbox that keeps one honest. I think I was just to tired after working all day to have the energy to get into trouble as I learned the trade of masonry construction is most demanding on the body.
As it turns out I developed a lower back injury that kept me from working in the trade actively – so I decided to go back to school and study architecture. It was in college that I began to appreciate the art of design and the process of construction as it related to historic and traditional masonry architecture. If I could no longer lift and set the stone – I could learn about how to preserve its original condition – and more importantly to do this in the means and methods of the original builders. This meant I needed to be willing to learn about traditional masonry construction tools, methods and materials. It also meant I needed to find other masons that understood these aspects of my new desire. The year was 1990 – 26 years ago. I researched my own family of origin in the masonry trade which dates back to 1870 in Posen, Prussia. So I was the 5th generation in my family to be involved in the masonry business. The problem; however, was that the oldest living relative that would had known about traditional masonry construction methods, workmanship, and materials was my great grandfather and he died in 1951. My grandfather died in 1979; my father in 1985.
As luck would have it I secured a job at a lime manufacturing company in 1991. It was during my employment I discovered an enthusiasm for historic mortar materials, which of course are based upon lime, and have been for thousands of years. Working with several conservators, architects, and a masonry contractor based in Toronto, Canada I began offering lime putty for use as a binder (without Portland cement) combined with sand at the jobsite. It was not long after; however, that I realized the need to train masons on the jobsite to use the Portland-free mix design and assist them in delivering the best quality possible. I traveled to England, Ireland, and Scotland over the next several years to work alongside other masons who generously mentored me in preserving historic masonry using lime mortars and traditional methods on castles. Then I brought that information back to the United States to assist in our training efforts here. That was 1998.
We made mistakes; we learned from our mistakes, we improved our methods, tools, equipment and materials. We did not give up. Encouraged from my mentor masons in Europe and Canada – I completed one project after another across the United States monitoring the progress as I went along. Writing, speaking and communicating with industry professionals I stayed focused. I wish to gratefully thank the pioneers in the masonry preservation movement in Europe that encouraged and personnally helped me like; R.H. Bennett, MBE, Winchester, England; Dr. Gerard Lynch, London, England; Mr. Douglas Johnston, Glasgow, Scotland; Mr. Patrick McAfee, Dublin, Ireland; Ms. Pat Gibbons; Charleston Fife, Scotland; the late Mr. John Ashurst, London, England; Mr. John Fidler, York, England; Mr. Colin Burns, Manchester, England; Mr. Stafford Holmes, London, England; Mr. Tim Meek, Charleston Fife, Scotland; Mr. Michael Wingate, England; Mr. Sam Trigila, Toronto, Ontario, Canada; Scottish Lime Centre; and English Heritage and the Society of the Protection of Ancient Buildings (SPAB) in London, England.
Since the early 90s I have been privileged to assist in the effort to establish (or best said, re-introduce) the lost art of true traditional masonry preservation with the use of lime mortars leading the way. As we continue this effort in 2016 we will actively be searching for architects and historic building owners that seek to preserve the architectural history and character of their properties by supporting the masons by offering onsite historic masonry training that is project specific. I strongly believe that by understanding our past and acknowledging the workmanship, trade practices, techniques, and tools used by the original masons in the process of the original construction we will have a better chance at success in the authentic preservation of historic masonry.
If we go into historic masonry preservation projects expecting that masons today should know all the details that are vital to the success of a masonry preservation project – I think we are asking for too much – especially in a low-bid environment in which many design professionals must deliver their services. Let us expect the best, write excellent specifications to support quality assurance – but we must be realistic in the understanding of what that actually means to the mason working at the site. In many cases these men and women have never worked with a straight pure lime mortar before so there is a natural learning curve that must be acknowledged. But we can not, and should not, let masonry contractors figure it out on the jobsite without proper guidence. This is why I started my company to do just that – mentor and help the masons through training. The same way I learned in Europe.
Speweik Preservation Consultants are not masonry contractors. We use our hands-on historic masonry experience to provide the necessary technical consulting services in: condition assessment, material testing, specification assistance and masonry contractor training at the project site. We strive to support the efforts of the Architects and Historic Building Owners in meeting the US Department of the Interior’s Secretary Standards for Rehabilitation in Division 4 and to protect the historic integrity of the architecture under repair consideration.
Pamela Bates received the 2011 the Peter H. Brink Award for Individual Achievement from the National Trust for Historic Preservation – announced in the Preservation Magazine November/December page 46. I was inspired to read her commitment to the Lowell’s Boat Shop in Massachusetts, the oldest continuously operating boat shop in the country founded in 1793.
Through its different ownerships and threats by big developers – for the prime waterfront property, the building survived after Bates assembled a coalition called Lowell’s Maritime Foundation which purchased the landmark. The nonprofit took ownership in 2007 and has operated Lowell’s ever since.
What I think is most dynamic about the preservation plan is it includes building wooden boats, a well-kept secret, in a working museum setting. People can actually go there and watch boat building in progress. I believe the best museums are the working museums – full of life, just like the old days when business was booming in the 1700s.
Today, I acknowledge Pamela Bates for her inspiration, patience, and preservation energy. Congratulations Ms. Pamela Bates and to the National Trust for selecting a great candidate for the Peter H. Brink Award for Preservation. I hope to someday visit this property in the future and hope you will too.
Lowell’s Boat Shop: http://www.lowellsboatshop.com/pages/pressmedia.html
As a young boy growing up in a family of stone masons mixing mortar was like brushing my teeth…I did it every day, at least during the summer months when school was out. Who would have thought that in the age of technology, speed and convenience that my great great grandfather’s 1846 mortar formulation would return. The trend seems to be one that is sweeping across Scandinavia, Europe and Canada as architects and heritage masons work together to preserve their country’s historic masonry properties built hundreds and often thousands of years ago. They call it the “Lime Revival” It’s been 30 years for Sweden, 20 years for England, 10 years for Canada….its America’s turn now.
The oldest archaeological sites in the world are, of course, masonry. As early as 2450 B.C., masons began using lime and sand for mortar. Lime is made from limestone (calcium carbonate) which has been heated to temperatures exceeding 1,650F where the heat drives off the carbon dioxide and water turning the limestone into quicklime (calcium oxide). Traditionally this quicklime (sometimes called lump lime or hot lime) was delivered fresh to construction sites or made on-site in a temporary kiln just for the job. The quicklime was mixed with damp sand and stacked up into piles for slaking into a hydrate powder (calcium hydroxide) and run through a screen or the quicklime was combined with water in the ground, formed into a putty (also calcium hydroxide), and mixed with the sand at a later time depending on the project needs. Either way, the mixtures were left to mature or rest for a time before use, due to the expansion of the lime particles during slaking.
The lime was generally mixed with local sand in a ratio of 1 part lime putty to 3 parts sand by volume. Other ingredients like crushed brick, clay, lamp black, and natural cement were sometimes found in smaller quantities before 1870; however, the basic lime putty/quicklime sand mortar formulation has remained unchanged for centuries.
Portland cement was first manufactured in America in 1871, but did not become truly widespread until the 20th century. As late as 1883 there were only three portland manufacturing plants in the U.S. Up until the turn of the last century portland cement was considered an additive, or “minor ingredient” to help accelerate mortar set time. By the 1930s, most masons were using equal parts of portland cement and lime putty or quicklime. Thus, masonry structures built between 1871 and 1930 might be pure lime and sand mixes or a wide range of lime and portland combinations.
What we do know about lime, and the reason for its come-back, is its incredible performance characteristics, and versatility as a time-tested building material – and not just as a masonry mortar either, but also as paint, (limewash/whitewash) exterior stucco/render, and interior plaster as well. Lime, when properly combined with clean, sharp, well graded sand can perform for many centuries in masonry applications. Lime has the ability to handle water without trapping it within a wall structure. It is breathable, flexible, obtains high bond strength to masonry units, it is truly sustainable (less energy is required to heat a ton of lime as compared to a ton of cement) and it has autogenious healing capabilities, often referred to as “self-healing” where hairline cracks do develop over time water combines with the lime again to re-knit the cracks back together. Limes durability comes through a process of what’s called carbonation. Carbonation is a process by which lime turns back to limestone by reabsorbing the CO2 back from the atmosphere though wetting and drying cycles. You can say that the material interacts with nature on a daily basis.
As portland cement became more widely used many lime sand mortars were being “covered-up” during repair projects. Exterior masonry buildings suffered badly from hard portland cement mortars (1940s until today) which did not accommodate for movement or stresses within the wall systems, and as a result, many historic brick and stone units got damaged by this un-sacrificial material. When cracks did occur, in the portland cement mortars, water would migrate into the wall cavities and not be able to escape or evaporate back out as they once had done with the lime sand combination mortars.
But times are changing. We are seeing signs of the “Lime Revival” hitting the shores of the United States. Mortar manufacturing companies are now offering lime mixes now for restoration and a few specialty companies offer traditional lime putty, quicklime and imported hydraulic lime for sale.
Lime mortar materials, that I am currently aware of, are available from the following U.S. companies listed in alphabetical order for your convenience. Be sure to ask questions about each of the company’s offerings, as they differ. Some still use portland cement in their lime mortars. It’s best to know what you need first – then go out and find a supplier that can meet that need.
Cathedral Stone Products
U.S. Heritage Group
Virginia Lime Works
Let me save you some time and trouble if you are considering specifying lime putty (ASTM C1489-01) for your next historic masonry restoration project. Forget about the standard way of mixing mortar with a gas-powered paddle mixer or drum type machine used in new masonry construction. These machines require the mortar ingredients to have a high rate of flow by adding enough water into the mixer to keep everything moving and mixing thoroughly. Not so with lime putty. This material is generally 50 percent water and 50 percent solid (looks like thick cream cheese) and requires a mixer that provides pressure or a kneading action to evenly incorporate the sand particles into the material.
Mixing lime putty and sand together works well when mixed by hand with a mortar hoe and shovel as you can place pressure into the mix by pressing down during the process. Ramming rods made from wood with handles also work well to beat the mortar into submission forcing the sand particles into the lime putty.
What is interesting about mixing lime putty mortar, if you have never had the pleasure to do so, is that it requires no additional water once properly mixed. There is enough water in the lime putty to create a good workable mixture that can be used for repointing. For years we have used a vertical shaft mixer that whips the material into form from the outside-in once all the ingredients are in the shaft mixer. So whatever you decide to do on that next historic masonry restoration project, if it involves lime putty, be ready for some good-old-fashion hand mixing or get ready for some buckshot of lime putty balls coated with sand!
The next time you come across a historic masonry building take a close look at the surface of the mortar joints. Yes, I know they often get over-looked in competition with the brick or stone, but trust me on this one. The first thing you should notice is the sand. The sand is the largest part of the mortar by volume and is the material that gives the joint its color, texture and cohesiveness. The next thing you should notice is white specs or small chunks of carbonated lime putty. If this evidence is identified you’ve got yourself a truly historic lime putty mortar. No need to hire a fancy consultant or pay for an expensive mortar test, you can with confidence declare your finding.
Mortars that display lime inclusions were typically mixed using quicklime and sand mixed on the jobsite with a shovel or mixing hoe by hand and with a lot of hard work I might add. Often, the moisture would be added to the sand first then the quicklime added to the damp material. The quicklime would slake first into a hydrate of lime then into putty if more water was added to the mixture.
The batch of mortar would be tossed and turned until the masons yelled out “MUD!” then the material would find its way onto the laborers back then unloaded onto the boards. The mortar would be placed in the wall as construction proceeded. Mortar consistency might certainly vary from batch to batch with this serve as you go system in place. There might be a time when a laborer catches up with the demand for mortar and has more time to mix a particular batch-thus breaking up the lime inclusions into smaller pieces and even dissolving them altogether.
If it is your desire to match these inclusions you have a couple of options. Use a mortar mixture made from damp sand and quicklime (hot lime mortar mix- allow 24 hrs before use), or make lime inclusions from straight lime putty by allowing the material to air dry then running the harden pieces through a series of aggregate sieves to match the inclusion size you specify. Then simply add the inclusions to your lime putty mortar just before application taking care not to over mix. The inclusions in the image above were added to the masons hawk just before installation and were protected from the initial mixing of the lime putty and sand to keep them from breaking apart.