NHL Link...
This link provides technical information on the Natural Hydraulic Lime products used on this project.Plaster, p8
Finish Coat
Due to circumstances beyond my control, the application of the finish coat had to wait until the late summer of '09 - over one full year after the application of the brown coat. A benefit from this delay was that many of the tiny cracks that had formed as the brown coat dried were now gone, healed via the ongoing carbonation process (see comparison).
I began the finish coat process the same as the scratch and brown, by taping plastic over windows and doors, then soaking the walls with water. For the plaster itself, I used a premixed NHL/sand product called Ecomortar. It combines very fine grades of sand with lime plaster in proper proportions to yield a smooth, consistant finish (see link to left for more info).
I emptied the contents of one bag of Ecomortar evenly into two five gallon buckets (it won't fit into one); these became my measuring buckets. Next I measured the required amount of water for one bag of Ecomortar and divided that between two additional buckets; these became my mixing buckets. I then poured the contents of one measuring bucket (dry mix) into the water-containing mixing bucket and mixed for a couple of minutes using a drill equipped with a bucket mixer. Also, the plaster manufacturer produces various powdered pigments to tint the plaster. These would now be added if desired. We left ours off-white, the lime's natural color.
Note: It is important when mixing to pour the dry plaster mix into a bucket already containing water to prevent unmixed clumps from forming and degrading the finish.