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Masonry and mortar mysteries unmasked
by Roger Faris
Every community needs more people like my neighbor Bob Martin. He is a tireless volunteer in our schools, community gardens, housing programs, youth employment and conservation projects. I also think of him as the professor of bricks and mortar. For over a decade he has volunteered to teach a class on bricklaying and tuckpointing at our local community center.
Over the years, several hundred people have learned how to repair their old brickwork or to confidently begin a new project. The word about these classes has spread throughout the region. One fellow drove his truck across the Cascade mountains to attend, and then returned home to Ellensburg late that night. I'll never forget how pleased he was to gain the knowledge that he sought.
Bob grew up in Birmingham, England, where the standards and traditions of masonry construction are impressive and ancient. He learned about the proper use of the hawk, trowels, and slickers through an apprenticeship which included working with his father and grandfather. When his students in the Seattle area shop at one of the local masonry supply stores, they inevitably toss out English terminology which they picked up from Bob. This always elicits smiles of appreciation from the salesmen. They all hold Mr. Martin in high regard.
At the beginning of class, Bob mixes a batch of mortar to show the ideal consistency. He adds a bit of mortar dye to demonstrate how darkening, or adding color to the mixture of sand, lime, and cement, can contribute to the beauty of the project. Next, we get to observe some bricklaying technique as he builds part of a chimney, which rests on a sturdy table. The work begins with a bed of mortar that is dropped into place from a large pointed trowel. The tip of the trowel is used to create a furrow in the mortar in preparation for the first course of bricks. The technique used to apply mortar to the end of each brick looks easy, at least when Bob does it.
Constant use of a level is one of the secrets of producing quality brickwork. Chimney corners must be kept perfectly plumb (vertical) by paying attention to the air bubble in the glass tube that is built into the leveling tool. The straight edge of the level is used to keep the faces of the bricks in line. To ensure the alignment of a long wall, string is stretched tight between a pair of corner blocks. As the bricks are placed, they are tapped into position with the end of the trowel handle. This squeezes out excess mortar until the brick is level and the joint is the required thickness (usually about 1/2 inch). Rocking the bricks from side to side is not a good idea, since this could leave a gap at the edge of the mortar joint. As the work continues, excess mortar is pulled away from the joint with the trowel in a way which avoids smearing it on the face of the bricks. You'll have to see a professional mason do this to appreciate the simple, yet important technique.
The mortar joints are struck off (finished) with special tools. These are selected to produce either a flush surface, a slightly concave, or a beveled appearance. Bob points out that a flush joint provides the most resistance to unwanted water penetration into the brickwork.
The masonry class also covers the procedure for raking out loose mortar in existing brickwork to an appropriate depth, and replacing it with new mortar. This is called tuckpointing, and Bob leads us through a brief history of this subject, and provides a practical demonstration. The participants have an opportunity to try all of the tools and techniques. Some of us drop a little mortar on our shoes.
In England, the final cleanup of tiny bits of stray mortar is accomplished with a brush. In our part of the world an acid solution is often used to remove mortar that got applied where it's not wanted. A more important difference between the two countries is in how chimneys are left to cope with our similarly wet climates. In Birmingham, they like to build a structure to last for hundreds of years. A chimney cap helps, as it keeps most of the rainwater from doing harm to the steel damper system at the top of the hearth, and from mixing with soot residue and creating acids which destroy the mortar. In Seattle, chimney caps are rare. Some residents have installed lightweight metal caps. They often rust, or blow away in a windstorm. Recognizing a need, Bob's wife, Katherine Tooker, crafted stainless steel molds which she uses to produce attractive and sturdy cement caps. She borrowed the shape from her favorite English style chimney caps, and now makes them in several sizes. Each includes a heavy lid which allows easy access for chimney sweeping.
I think of Bob Martin as a keystone in our community, but have discovered that he has also donated his time and energy in projects from Capital Hill to Calcutta. Volunteering in schools seems to be a particular interest. When I asked him about it, he explained that he believes the schools are nearly overwhelmed by the challenges that they face. He sees a need for everyone to pitch in and help if our communities are to have a future. Bob is also skeptical of critics who attack our schools while remaining ignorant about what is taking place within them. He wants us all to keep our masonry in good repair, in part to make it harder for vandals to throw bricks at a system that is always expected to do more than is possible with the resources that are provided.
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