Tadelakt Plaster Application At the Bucks County Designer House & Garden

LimeWorks.us was commissioned to complete a Tadelakt plaster application at the Bucks County Designer House in Doylestown PA. Tadelakt is a very traditional plastering technique which originated in Morocco.  It’s especially applicable for bathrooms due to its resistance to water. Using a natural hydraulic lime based plaster, Randy Ruth spent a few days completing the plaster application.  His approach included a three coat application using TAKCOAT™ as the base and a custom blended scratch and finish coat consisting of “color: #008000;”  in a base of Ecologic® Mortar and Natural Hydraulic Lime.

Take a few minutes to look through these progress photos.

BC-Designer-House-15 BC-Designer-House-34 BC-Designer-House-33 BC-Designer-House-32 BC-Designer-House-31 BC-Designer-House-28 BC-Designer-House-27 BC-Designer-House-26 BC-Designer-House-25 BC-Designer-House-24 BC-Designer-House-20 BC-Designer-House-14 BC-Designer-House-13 BC-Designer-House-10 BC-Designer-House-9 BC-Designer-House-7 BC-Designer-House-6 BC-Designer-House-4 BC-Designer-House-2 BC-Designer-House-1

All Photos © Sean K Maxwell

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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.

LimeWorks.us
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

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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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