How to Plaster a Wall

by on December 23, 2012Faith McGee

how to plaster a wallIf you think plastering a wall is like icing a big cake, you’re in for a big surprise. For one, you don’t get to lick the bowl afterward. Much like baking, there are some hard and fast rules when it comes to plastering. For example, you must mix the correct amount of dry plaster with the right amount of water. Too much water and the plaster won’t stay on your trowel. Using too much dry plaster will prevent the plaster from spreading evenly across the wall. Only use clean water. Rainwater or water from the pool isn’t going to work. Read the mixing directions on the bag before mixing. Almost all plaster mixes need a specific ratio or amount of water. For instance, certain types of veneer plaster mixes need 18 to 20 quarts of water per 50-pound bag.

Timing

Think anytime is a good time to plaster a wall? Think again. Plastering a wall during the hot summer months can cause the plaster to set up too fast. Too much humidity will cause the plaster to drag.  Control your set-up time by setting the temperature between 55 to 60 degrees Fahrenheit. Likewise, sunlight is your friend when it comes to plastering. In a room full of windows, be sure to open blinds or pull back curtains.

Plastering Technique

It’s all in the technique when it comes to successfully applying plaster to a wall. Like salsa or the mambo, plastering a wall requires finesse and the right moves. First, the wall should have its wallboard up, seams must be taped and base coat should be applied on all the joints. Get your hawk wet. (A hawk is a plasterer’s tool that has a flat surface and a handle.) A dry hawk will cause the plaster to stick, which will make transferring the plaster onto the trowel difficult. Use a trowel to help scoop up the plaster onto your hawk. Think of the hawk as a palette that you’d use for painting. Swirl the plaster onto the center of the hawk. Clean off the edges of the hawk. Scoop up the plaster (or mud as the professionals call it) from the bottom of the trowel.

Ready, Set, Go

As soon as you start plastering, you’ve got 30 minutes to work with the plaster and 45 minutes to an hour before the plaster will be completely hard on the wall. The faster you can get the plaster onto the board, the more time you’ll have to smooth it out. It’s kind of like running a marathon, but without the starting gun or the running.

Start at the bottom of the wall. Gently, press the trowel against the wall and move up. Move over a few inches and go from left to right, working from the bottom to the top. Keep the pressure the same. It helps to bend your knees as you’re coming down. Stretching before plastering isn’t a bad idea. The idea is to have the plaster slide off the trowel and evenly onto the board. Any interruptions can prolong the progress or compromise your entire mission. Turn cellphones off. If you’re working around kids, have them rate your technique. Make plastering a wall your next family night activity! Or not.

Smoothing the Plaster

You’re trying to achieve a smooth finish. Any holidays (blemishes) will create more work for you when you start painting. In fact, fixing a holiday requires applying joint compound and sanding. Those are two activities that you don’t want to do after plastering a wall. If you do wind up with some holidays or an uneven area, don’t worry. It takes the professionals roughly one year to become comfortable with using a trowel and another year to achieve a “paint-ready” finish.

What About the Top?

How does one plaster the top of the wall? Very carefully. Use a ladder to spread plaster from side to side. Asking someone to hold the bottom of the ladder is not the worst idea in the world. Using stilts may sound tempting if not exciting, but leave that to the professionals. Plastering a wall should not involve a visit to the emergency room. If you’re one of those people who enjoy the look of painted walls instead of plaster, wait 30 days for the wall to completely dry before painting. Do not jump the gun. You’ll wind up with an uneven finish. Spend the next 30 days admiring your successful project. Plastering is not an easy project, but some good techniques will put you on the road to success.

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