The application of the lime plaster is very similar to the application of cement stucco. A few precautionary steps MUST to be followed in order to achieve good results:
- PROTECT THE WORK BY USING TARPS
Curing and suction control are the most important factors. The slower the curing, the better the result. It is important to use tarps, burlap, etc. to protect the work for several days from adverse conditions such as sun, wind and rain. If conditions become too excessive, it may become necessary to mist water on the walls.
- MIXING TIME
For NHL 3.5, NHL 2 & NHL 5 (when adding your own sand), mixing a minimum of 10 minutes is required. Be very careful not to add too much water at the beginning. Measure the water carefully. The lime is going to hydrate slowly and too much water will result in a “slurry”.
NOTE: for Ecologic™ Mortar (premix, no sand needed) mixing time is five (5) minutes maximum.
- TIME BETWEEN COATS
Wait a minimum of 10 days (or longer) between coats.
- WET THE WALLS BETWEEN COATS
At the end of the day, the day before the application of a new coat (brown and finish) we recommend that you soak the walls to allow them to absorb as much water as possible. Do not have any water running or dripping down the wall at the time of plastering.
- REWORK THE PRODUCT
NHL can be reworked up to 24 hours after application depending on the weather conditions. This is possible mainly because there is no cement in it.This is a huge advantage. If some cracking occurs in the brown coat, the applicator can mist the crack and close it up the next day, allowing for a flawless result. Drying conditions can reduce that window of opportunity so take advantage of it.
Although most of the steps we recommend are similar to the recommendations of the PCA or Portland Cement Plaster (Stucco) Manual, most of applicators do not follow these guidelines. The additives that are in Portland Cement compensate for these lapses, as well as improve productivity and workability. The lime that is specified on your project is called Natural Hydraulic Lime or NHL. The European Norm EN 459-1 specifies that NHL cannot contain any additives or any additional materials. It is considered a pure and natural product. Consequently there is nothing in NHL that will help to compensate for lack of workmanship or allow the contractor to “cut corners”. The material tells the applicator how to work, not the other way around.