Weather and Plaster
Weather and Plaster, alternatively known how as Earth Wind & Fire interact with Plaster
When applied correctly, plaster can give any surface a variety of beautiful finishes. Though even with a skilled artisan, the perfect plaster finish can be difficult to accomplish due to a variety of outside factors. Temperature, humidity, and wind speeds can negatively affect the way that plaster sets.
Since plaster is made through the combination of a liquid and a powder, humidity levels can greatly impact the way that the material reacts during application. For example, a warm wall may cause some of the moisture in the plaster to evaporate, making it weaker and more prone to cracks. If you plaster in below freezing weather, the plaster (especially water-based material) will freeze and weaken. We have worked in both settings, this why we ask for a temperature controlled area in most cases.
Temperature isn’t the only environmental factor that can impact the way that plaster sets—if you’re applying plaster outside, be cautious of wind. Wind can cause moisture to leave the plaster, making it less workable and weaker. If you’re working inside, close those doors and windows!
The consequences of applying plaster under non-optimal conditions aren’t just aesthetic flaws like cracks; over time, plaster that was applied frozen can fall off in chunks, causing serious safety hazards.
When plastering a large space, it is possible to be dealing with multiple temperatures at the same time. For example, we did a job this past winter in a lobby with very high ceilings. Up at the top where it was warm (because heat rises), our SET plaster dried very quickly. However, down on the ground, due to the door to the lobby opening and closing rather frequently, the SET behaved rather differently and took much longer to dry. The differences in drying times gives the final look two distinct finishes instead of one uniform one. It also makes the work of the drew on the top levels of the job much harder and strenuous.
I’m sure you’re wondering, what are the optimal conditions for applying plaster? The suggested temperature range for applying cementitious materials like plaster is between 40 and 70 degrees Fahrenheit. This temperature range, plus someone skilled with a trowel, will guarantee a lovely non-frozen, non-evaporated plaster finish.
