Discussion on Masonry Preservation and Sustainable uses for Lime


Join us June 27th in Lancaster PA at the Central Pennsylvania Preservation Society. Lab Tech Randy Ruth will be presenting on the importance of appropriate masonry restoration with lime and the harm caused to countless historic structures across the country by Portland Cement. Randy will be presenting on 3 main topics and doing demonstrations. The event is free to the public and light refreshments will be served.

Review the presentation topics below and follow this link to register.

Historic Mortars: The Chemistry that Binds our Built Environment will review the use and development of masonry mortars spanning over nearly 5,000 years, as well as the basic chemistry of mortar manufacture and application and the role it plays in masonry buildings today and prior to 1870.

Masonry Preservation: Technical Applications of Common Masonry Problems will dive deeper into the application of different types of mortars to solve common masonry issues. Benefits of lime mortars will be discussed – including suitable Portland cement applications. Silicate consolidants, stains, and paints will be touched on regarding painting new buildings and preserving older structures.

Preservation & Sustainability will bring together the history and preservation of masonry and mortars to show how the preservation of masonry structures via adaptive reuse is key tot the sustainability of a community. Concepts such as urban planning and architectural significance will be touched on, as well as traditional building methods for low-rise new construction and how it affects a local economy.

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Tadelakt Plaster Finish is FINISHED at the Bucks County Designer House

The walls are complete in the powder room at the Bucks County Designer House in Doylestown, PA. Here is a photo to tickle your fancy…

This Tadelakt Plaster application was done using all natural no VOC Takcoat™ as the base and a custom Ecologic™ Mortar for the second and third application.

Visit the Bucks County Designer House May 5 – June 3 in Doylestown PA.





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Understanding Mineral Paints and Stains for Masonry Applications

Ecologic™ Silicate mineral paints are mineral paints made using potassium silicate, also known as waterglass. They are combined with inorganic, alkaline-resistant pigments and these paints have zero VOC offgassing.

Silicate Mineral paints were patented in Germany during the late 19th century. Examples can now be found around the world in masonry conservation and alterations as well as new construction. This long track record has proven these paints and stains are durable, long lasting and low maintenance applications for all types of masonry.

Mineral paints and stains chemically bond to all forms of masonry substrates such as brick, stone, mortar, stucco and cement. Unlike latex paints, they are non film-forming, creating a permanent bond that works in harmony with the masonry. Ecologic™ Potassium Silicate Paint is a thick bodied paint.

Ecologic™ Colorwash Stain however is a translucent potassium silicate stain that allows the masonry texture to come through the finish. Both can be brushed, rolled or sprayed on. For artistic expressions or when feathering colors with Ecologic™ Colorwash Stain a sponge may be appropriate for a unique finish.  For long lasting, breathable applications Ecologic™ Potassium Silicate Paint is an exceptional choice, while Ecologic™ Colorwash Stain may be more appropriate for changing previous masonry repairs where there are mismatched colors.

Both are available in 10 standard colors and can be custom ordered.

For more information about mineral paints and stains as featured in This Old House Magazine, or to learn about our line of  lime paints please visit our website or call 215.536.6706.

Phone: 215-536-6706

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What Sand Should I Use With Natural Hydraulic Lime For Repointing My Building? FAQ Friday with Randy Ruth


Quick and short of it…. Make sure the sand meets ASTM C-144. But you might ask yourself, what the heck does that mean? ASTM C-144 is a standard specification for aggregate for masonry mortar, brought to you by the American Society for Testing Materials (ASTM). To start off many people will use the term aggregate rather than sand. This is because aggregate is a broader term which can refer to recycled materials that can be use in lieu of sand if so desired. The specification has a lot of good guidelines to follow when choosing sand, such as cleanliness, shape, composition and grain size distribution.

Good, clean sand is important. Depending on where you, get sand you may run into some complications. If you’re purchasing your sand from a distributor, pre-bagged sands are very clean as they are typically washed and dried. However, bulk sand may have some impurities, it is unlikely but should be noted for other potential issues discussed in a moment. If you are getting sand from a nearby creek or stream for historical purposes, be careful. You should check with your local laws to see if it is even legal as there could be environmental implications. That being said, be sure that the sand is free of silt and organic matter.The shape or sharpness of sand will help make a mix denser and create overall a more durable mortar. Angular aggregates fill in void spaces better then rounded sands. A good visual for this is to try and imagine a case of bottled water with round bottles, now imagine the same bottles but square. The square bottles will be tight against each other, while the round bottles only touch at four contact points, leaving voids.

Composition of aggregate will determine long term effects of the mortar. There are aggregates out there that can cause delayed expansion and failure of mortar. One to look out for is crushed dolomite limestone. There are others but for most restoration work that is the most common. Your local supplier should know if they carry this type and will most likely not recommend it for any masonry mortar.

Grain size distribution is the most important factor, when choosing an aggregate. The ideal sand should have a wide range to sizes in its composition. Workability and durability are greatly affected with good distribution. If you can gain access to a sieve analysis, look for a bell curve when the numbers are plotted on a graph. This shows that there are a few large pieces, an increasing amount of medium sizes and a small amount of fines or powder. Excess fines in a sand result in poor workability and is often corrected by an excess amount of water, resulting in poor durability.

Good sand that is clean and dry will have a theoretical void ratio of 33%. In other words, given a certain volume of sand there will be an ideal space of air of between the grain of 33% and 66% sand. fortunately there is a simple test anyone can do to see what the void ratio of sand is.

First get two clear containers one being at least twice the size of the other, fill the small container with water and pour it into the large container and make a mark. Then fill the small container again and pour it into the large container, being sure to have left the first measure of water in the container. Mark the level of the second measure and space 4 lines evenly between the two creating a total of six marks on the large container. Empty the large container and fill the small container with water. Pour the small container of water into the large container, reaching the bottom of the six lines. Now fill the dry small container with dry sand pour it into the large container. After everything settles you will be able to see how much water was displaced. Starting with the top line representing 0%, each line moving down the large container will represent 20%. The resulting percentage will be the void ratio and represent the minimum amount of lime by volume you should use to make a good mortar.

Poor sand can have ratios above 50% and will increase the amount of lime required thus resulting in added expense for you project. So when in doubt conduct a small test on the available sands choose the one that has a ratio closest to 33% to save on the amount of lime required and sleep easier knowing that you have decent sand.

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“Soft Reds and Hard Tans” Exploring Historic Masonry Architecture in the French Quarter

by Randy Ruth

New Orleans. It’s quite the town especially during the weeks leading up to Mardi Gras, known as Carnival. Technically beginning on January 6th and concluding on the day before Ash Wednesday (aka Fat Tuesday), the long celebration is concentrated on the final few weeks, giving rise to more frequent parades and events.  Granted I had never been there before but what I expected was much different from my experience. As a Philadelphia native, I had assumed that it’s nothing but one insane party similar to events that might occur during the Mummers parade on New Year’s Day in Philly, and be only on Fat Tuesday. What I had experienced was by far richer in both culture and architectural significance. I don’t mean this to down play the heritage of historically significant Philadelphia. It’s just that New Orleans has a charm that I believe to be facilitated by it organic architectural style, originating in function over form.

Spending most of my time in the oldest neighborhood in New Orleans also known as the French Quarter or as some may traditionally refer to it as Vieux Carré, I felt a certain type of warmth from the people and its buildings. The symbiotic relationship felt I found to be rooted in the architecture bound mostly by French, Spanish and African influence. This dynamic create a true Creole culture. Perhaps this is why nobody can exactly pinpoint the exact year that Carnival festivities began, a very real unique place and people whose origins can be traced to their roots but only studied in regard to its complex organic creation. The trend can be translated to local architecture in the French quarter however it is a bit easier to study.

A New Orleans local showed me around the French Quarter explaining all the influences of Spanish, French, African and local climate on many of the buildings architecture. Probably the most iconic would be the balconies and galleries extending over the sidewalks. Just to be clear balconies are cantilevered into the building with no supporting posts extending halfway over the sidewalk, while galleries typically extend to the edge of the street. Unbeknownst to me I found that the reason for this is threefold.

First, has to deal with the influence of the Spanish and French architects designing buildings since New Orleans beginnings. However, more often than not these buildings needed to be protected from the weather. Wind driven rain during hot summers created the need to have large open windows to permit air flow but something needs to prevent the buildings from getting wet on the inside, hence the need for balconies to act as an eve to prevent rain from entering the interior. The same principle also protects the inferior masonry walls. New Orleans suffers from poor clay local clay for making bricks. The result being bricks called “soft reds & hard tans” that in most cases must be protected with a stucco or render of lime.




What is currently known as the Napoleon house was first occupied by the mayor of New Orleans from 1812 to 1815. Although Napoleon never came he was offered this residence during his exile in 1822.








Detailing of deteriorated “Soft red” brick rendered with lime stucco as a Trompe L’oei to imitate limestone blocks on the Napoleon House.




Another defining characteristic of architecture in the French Quarter is the entresol, also known as mezzanine. Entresol’s were needed for storage in commercial buildings due to the high local water table.  Looking at the exterior of a building one can clearly notice the well defined tall window front that help hide the storage floor between the 1st and 2nd floors.




This store front exemplifies the use of an entresol commonly found in the French Quarter.




Due to New Orleans high water table, rising damp is a big issue for many of the building. Because the majority of the historic Buildings located in the Vieux Carré district were built before the advent of Portland cement, lime was used and accommodated moisture very well.  However, today pure lime technology is used to restore the local historic properties, which results in fewer lost or damaged cultural resources.

The time I spent in New Orleans was certainly too limited. There was far too much to see in the few days I was there. Its impact left me forever moved by its places and people. For anyone who has not been there. GO! The treasure hidden in the city is everywhere, waiting for people to experience it and take a piece of it home. Perhaps the next time I visit I will see you there.



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A Green Portland Cement Alternative, FAQ Friday with Randy Ruth


You might ask yourself… How is Natural Hydraulic Lime (NHL) a green building material? The simple answer would be that it releases about 80% less CO2, pound for pound when compared to Ordinary Portland Cement (OPC) during the manufacturing process. But why is this so? Well that requires a bit of understanding on the manufacturing of the two very different products.

Both NHL and OPC are made from limestone, although not necessarily the same kinds of stone and are fired in a kiln. NHL is produced in Vertical shaft kilns, which is like a big chimney, with natural gas or clean coal at a low temperature. While OPC is burned in a rotary kiln fired at nearly 2,500 F. The amount fuel used to maintain such a high temperature is by far greater than the relatively low firing temperature of NHL. Often hazardous waste is used as a fuel, which can emit toxins into the atmosphere. During either process CO2 is driven off into the atmosphere. Even though NHL production drives off less CO2, the benefits don’t stop there.

When the NHL is ready to be mixed as a mortar right out of the bag, it’s hungry. NHL wants the CO2 that was pumped into the atmosphere back all for its self, in its natural process to turn back into a limestone. As different grades of NHL are produced their whiteness and density change. On a scale from lightest to heaviest and from whiteness to grayness, NHL 2 is Light and white while OPC in heavy and grey. Since mortar is mixed by volume in the field, less lime is used per pound to make up the same volume of mortar using OPC.

For more info and to purchase visit us here: limeworks.us/nhlmoreinfopage.php

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Chalky Finish With Lime Paint, FAQ Friday with Randy Ruth

Q: I want to use Lime Paint as a finish of my basement walls but am worried about it chalking. What can I do to prevent or fix this?
A: When used as a finish over any sort of acceptable masonry, Lime Paint can create a beautiful durable finish when applied appropriately. Chalking of a Lime Paint can be reduced when it is applied in numerous very thin coats as always recommended. Although it will not be eliminated, it will certainly help for the longevity of the coating. Now if chalking is of the upmost concern there is a simple solution. By applying one thin coat of PrimaSil, (potassium based “water glass”) almost all chalking is eliminated. The color of the finish may change slightly depending on the absorbency of the background and Lime Paint. Typically, this is so slight that it is inconsequential.

Click here for more information on our Lime Paints

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Checking up on the Lithomex Repairs at the Metropolitan Museum of Art


A team from LimeWorks.us recently ventured up to NYC. While there, they took some time to visit the Metropolitan Museum of Art where a repair campaign in 2005 used St. Astier Lithomex to do a number of repairs on the Fifth Avenue street facade. Lithomex is a Natural Hydraulic Lime based stone and brick repair material that is environmentally friendly and a more suitable product for repairing sandstone compared to modern epoxy or Portland cement based repair materials. During the preliminary phase, it was discovered that the museum had suffered significant damage due to the use of Portland cement based mortars with relatively low porosity in earlier repair campaigns.

Lithomex has been used throughout the country for stone repair on historic brownstones, sand blasted brick buildings and decorative masonry. Because of its Natural Hydraulic Lime base, it’s an environmentally friendly and LEED qualifiable product.

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Total Repointing, FAQ Friday


Q: What is the correct method for total repointing?

A: Correct total repointing requires removing the joint to a depth of approximately 2-1/2 times its width and then using a compatible mortar in relation to the final p.s.i. and both the liquid and vapor transmission rate as that of the remaining joint and brick. High lime content pointing mortar is compatible with the soft and absorptive nature of historic brick which rely on their “fired skin” to protect themselves and the building from rain intrusion. If high concentrations of Portland cement were in the repointing mortar instead of lime, when moisture in the brick were to expand and contract during freeze/thaw cycles, often the unyielding mortar forces the softer face of the brick to exfoliate thus leaving a vulnerable unburned “salmon” center of the brick exposed to the elements.

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Historic Fabric melded with Traditional Mortar at the Irish Hunger Memorial in New York City


Blocks from the World Trade Center Memorial and the construction site of the new World Trade Center sits a half acre patch grass dedicated to raising awareness of the Great Irish Famine. This memorial was under construction on September 11, 2001 when the Twin Towers fell. The memorial saved that day, simply because of the direction the wind was blowing. The plume of dust blew from 1 World Trade Center in just a way that it didn’t touch a single stone, all of which were donated from each county throughout Ireland. Even a 19th century cottage was disassembled in the County of Mayo and re-laid in Manhattan using a lime mortar that was determined to most closely match that of the original. The memorial was dedicated in 2002 by former New York mayor Ed Koch.

A team from LimeWorks.us recently visited the site and put together a collection of images seen below. The names carved in the stones represent the counties of Ireland. St. Astier Natural Hydraulic Lime was used throughout the memorial walls and cottage, supplied by LimeWorks.us. The structure has been holding up very well and we are very proud to have been part of this important piece of built heritage.



















All photos Copyright Sean K Maxwell

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