I have used integral color plaster on every straw bale house I have built and I have always wrestled with the pros and cons of doing so. Integral color plaster means that the final color for the wall is placed in the finish plaster coat. The wall surface that is created is both beautiful and strong. It is unlike any other finish I have seen. The problem with it is that patching holes and fixing blemishes is quite difficult.
When a patch is made, especially in a Diamond plaster, often the whole wall needs to be resurfaced in order to hide the patch. This is not true with Earth plasters which rework well and hide patches. They, however, have a separate list of pros and cons that go along with them.
If paint is used over the plaster wall, it allows for easy patching of holes and blemishes. Simply repair the damage and then sand the patch even with the surrounding area. Once smooth, cover the patched area with paint to match the rest of the wall. The down side of this is that the wall loses its depth and character that the plaster provides by becoming more uniform in color. In addition, the paint may have adverse affects on the walls by trapping moisture inside the house that might otherwise have escaped. Some building codes, however, require an application of a low permeability coating on the interior surface of walls. Paint can fit that bill in some cases.
I have a new client that wants a painted finish on the walls, so I will get a chance to play out my assumptions about working with plaster and paint in place of integral color plaster. Unfortunately, it will be about 5 months before I get to fill you all in on the results of that house! Stay tuned…