Archways add interest to your home, turning an ordinary doorway into a feature. The plastering finishes the construction process. Learning how to plaster your newly constructed arched opening may take a bit of practice but with time and patience, it is a DIY-friendly process. Take your time and apply several thin coats and you'll be pleased with the results.
Pick up enough plaster to fill a good-sized coffee cup on the end of the trowel.
Scrape the plaster off the trowel and onto the archway. You're not plastering at this point, just transferring the plaster from your trowel to the arch.
Turn your trowel so the long end is against the arch at an angle of about 45 degrees and pull the plaster upward. Apply this first thin layer of plaster, called the skim coat. Let this coat dry overnight.
Create a clean edge around your arch using a corner and edging tool. This is an L-shaped trowel that you press against the edges and run all the way around the arch to make the edge consistent in its shape. Allow the plaster to dry overnight before applying additional coats.
Make each coat of plaster as smooth as possible. If needed, sand any imperfections with high-grit sandpaper, wiping clean with a tack cloth, before applying the next coat of plaster.