Do It Yourself Plastering Techniques for Patching
Tips on Residential Plaster Patching
Plaster is a hydration product, just like concrete. When you add water to dry plaster mix, you begin an irreversible chemical and crystallization process.The water and air content of the mix is critical. Timing is important, as the plaster has to be "finished" at just the right time. It is not a job for the rookie.
However, several manufacturers have developed different plaster products. They are fast setting plaster compounds. These products are dry powders. You add water to them and they begin to crystallize or "set" just like plaster. They are available with different "set" times. Some of these compounds, however, are sandable. They allow you to do quick repairs to surfaces in a one-step operation similar to plaster. You can teach yourself some basic plastering techniques by working with these materials. As they begin to 'set' or crystallize, you can trowel them to a smooth finish, just as you would plaster. Or, if you are unable to achieve a smooth finish, you can sand them after they dry completely (assuming you used a sandable compound!).
If you live in an older home with a conventional plaster wall and ceiling system, you should consider using these compounds to patch your plaster. Premixed vinyl joint compounds do not always bond well to the sandy plaster base coats. The quick set joint compounds, because of the crystallization process, actually grab to the old plaster much better. As the crystals in these compounds begin to grow, they interlock in the rough, sandy texture of the fractured plaster. Once you have applied the quick set joint compound, you can always skim over the patched area and existing plaster with a ready mixed compound to fill any small nicks or scratches.