Category: Natural Building Techniques

Lime-stabilized earth is one of the most versatile plaster base coats for natural buildings – it bonds well to both clay and lime, it’s a versatile plaster that can be used to level walls with fills up to 2″ deep or more in spots. A lime finish coat is applied over top for weather resistance. In this post I’ll share a recipe for lime-stabilized earth that’s a hybrid of two recipes you can find in our book Essential Natural Plasters – one recipe comes from Vermont-based New Frameworks (p. 87) the other from Ontario-based Straworks (p. 89 – you don’t

In Part one of this post we looked at clay-based plasters; now we’ll examine the other natural binders, all of which are different from clay in that they have a chemical set. Gypsum Gypsum is one of the oldest plasters, and because it can be cooked as low as 350 degrees Fahrenheit to create a binder, it is in fact among the most ecological. Gypsum is a soft, fairly common mineral that is formed when sulphuric acid (typically from volcanoes) reacts with limestone. It is carried in solution and deposited in layers on sea-beds, and over time it forms into

As their name implies, binders glue the other elements of a plaster together. More than anything else the binder defines the properties of a plaster including strength, permeability, and resistance to weathering. Over thousands of years of natural plastering there are three major binders that have been traditionally used: clay, gypsum, and lime. There’s a lot of variation within all three. Lime in particular is further categorized into hydrated lime, natural hydraulic lime, and natural cement; all of which have very distinct properties and are considered as unique binders. But for simplicity let’s look at the properties and origins of the

Sand is underrated. It provides the structure of plaster, and the quality of your sand can make the difference between success and failure. So what makes sand good or bad? In general, good plaster sand should be sharp, with a diversity of particle sizes, and clean. Sand should be sharp and angular, not worn and rounded. Imagine trying to build any kind of structure out of balls vs blocks, and the reason for this becomes obvious. Unfortunately this means that many natural sands are poor plaster sand. Beach sand in particular should be avoided, because waves have often been rounding

When spaghetti sauce meets unsealed earth plaster, it’s a bad scene. But it’s fixable. Most bad things that happen to natural plasters are repairable. There tends to be a trade off between durability and repairability – an unsealed earth plaster is the easiest plaster to damage, and also the easiest to repair without a trace. Lime plasters can be a little harder, but there are definitely tricks for repairing them. Also the more polished and perfect a plaster is the harder it is to blend in a repair; if there is very little variation in your surface, any blemish is

More earth and lime finish plasters at naturalplaster.ca