Plaster Testing:

     Ingredients

     Test batches

Applying Plaster:

    Techniques

    Case Study

Earthen plasters can be applied to any number of structures or materials including cob, adobe, straw bale, rammed earth, etc.  Certain techniques will help to ensure that the plaster is applied smoothly and will not slough off as it dries.  Here are a few handy tips:

Wet the Surface- The soil-based plaster will cling better to a wet surface due to the adhesion of water.

Mechanical Bonding- Use techniques such as poking small holes in each layer or scrapping with a toothed trowel to create a textured surface for the plaster to cling onto.

Add a Bonding Layer- When working on a smooth surface or straw bale, it is a good idea to add a layer of fiberglass, chicken wire, or burlap to give the plaster a surface on which it can bond. (see picture below)

Successive Plaster Layers- You may find it necessary to apply multiple layers of plaster.  Texture each layer and let it dry completely before adding the next.

Trowel- Smooth the final layer with a trowel.

Clay Slip/Aliz-  For added protection from the elements and with most formal building projects, you will want to add a a final clay slip on the outer surface.  For more information on clay slips check online for articles and recipes.

 

Bonding layers: here are two examples-chicken wire and burlap sack bolted to a brick wall.