This is part of a series of blog entries that will feature mason, Randy Ruth.
Randy was the former lab technician at LimeWorks.us and received lots of questions on masonry and the use of our materials. We post some of these questions on our blog. Look for “FAQ” in other titles of our blog.
Q: I have an old stone basement foundation (house was built in 1900) and need to “re-point” or fill in holes in the basement walls. Would your Ecologic mortar work? I am not sure that lime based mortar was used originally; would this still be OK or how can I tell if lime was used?
A: “cement” was not produced in the United States until 1870 in Coplay, PA, only up until around 1910 was Portland cement starting to find its place in society as a masonry binder. Prior to 1910, most mortars used were based on either lime putty, Natural hydraulic quicklime, or natural cement. Regardless of what the exact mix design was used to build your basement foundation, Ecologic™ Mortar would most likely be suitable for repointing your old stone basement foundation walls as it would be sympathetic to the adjacent mortar mix by maintaining good vapor permeability. An easy way to determine if you have a lime based mortar, especially in stone construction, is to break a piece from the wall and visually inspect for any white nodules or specks. The white nodules are an indicator of what is called a “hot lime” mix and commonly found in stonework. Any presence of those nodules or specks suggests a high lime content mortar, and should thus be repaired with a comparable material.
Of course following the Lithomex technical data sheet is important to ensure a quality application, but what about the little things that can’t fit on one sheet of paper? The small details that help make good finish “POP” into a quality indistinguishable patch. There are many things that are far to subtitle to translate onto paper from experience and feel of mortar and trowel. So practice, timing and tools are critical overview subjects to be discussed here.
Practicing patching old single salmon bricks not in a wall is a cheap and technically challenging exercise. The porosity of salmon bricks demonstrates the importance of controlling suction. If suction is not controlled, bond failure can occur while detailing outside corners. It’s these corners that give rise to the technical challenge. By coating multiple sides of a brick, it helps create focus on multiple surface planes. The initial reshaping step doesn’t have to be perfect. It just has to have about 1/8 inch extra material beyond the desired finish. Once Lithomex is well bonded to three sides of a brick, wait for the material to stiffen to thumbprint hard.
Re-troweling the surface will compact the patch to compensate for any slight shrinkage. While using trowels, squares, straight edges, miter rods and improvised tools to shave back and cut away undesired material to the finished profile will create the rough finish. When finishing a masonry unit in a wall, long metal straight edges are great to use as a profiling tool. With the edges exposed over to adjacent units or edges, they act as a guide to bring the finish to proper plane. Typically much of this profiling can be done in the first day of patching; however 12-24 hours later more intricate detailing and carving can be done. Tooth chisels can be used during this time frame to scratch in tooth marks or crandled finishes.
As more time is allowed to let the patch “firm up” stone masons chisels can be used in a traditional method to give more authentic characteristics. Sanders and rubbing block are also useful for honing the surface to a more polished or pristine finish.
Following these tips and practicing will build upon previous experiences for the craftsman or aspiring novice, facilitating a better rounded approach to brick, stone and terracotta patching.
Often when applying Lime Paint the surface texture may be rough, such as that of a brick, stone or stucco. A good brush for Lime Paint should be made of a high quality, durable natural bristle. What would be the most distinctive difference is the size. The wider thicker ferrule allows for more bristles and allows for a greater painting efficiency, due to its greater capacity to carry the thin paint.
Q: I have an old brownstone house and some of the stone have been falling off, what can I do to prevent further damage and fix the damage that has already occurred?
A: When you have brownstone deterioration or any form of stone deterioration and want it to stop, you have to first identify the root cause. Sometimes it’s as simple as replacing downspouts or replacing roof flashing, to prevent further damage to the stone. Other times it can be a long complicated series of tests and empirical analysis. Depending on the cause of the deterioration of the brownstone, a number of solutions can be applied.
If the stone is only sugaring or sanding with light deterioration, then perhaps doing nothing for a maybe a year and watching the stone for further deterioration is sufficient. However, if the stone is in much worse shape with possibly a ¼ inch or more of stone loss, then some could be some very serious problems with the integrity of the stone.
Brownstone as with many different types of sandstone has bedding planes. These bedding planes in the stone tend to detach from one and other depending on how the stone was laid in the wall. Imagine a layered cake as the stone, with each layer on top of one and other. If the stone cake is put on its side there is a greater chance that moisture can get between the layers and cause delimitation and or exfoliation. This being a common problem associated with sandstone, a more detailed resource for classifying the type of stone loss you may have can be found here.
It is always recommended that when fixing damage to stone that a qualified professional be brought out to see what the damage is and come up with an appropriate course of action. There are many different ways to approach fixing a stone like whether consolidation is appropriate is an appropriate first step or not. In my eyes, it is always best to honor the original detail of the stone and artisan who created it by only fixing what is broken. When patching stonework an important approach is to make sure that appropriate sympathetic patching materials are used. (Lithomex) The use of impermeable materials can cause further deterioration of the stone by trapping moisture. This will result in a faulty patch that can accelerate deterioration to the adjacent stone.