If even a small trace of plaster leftover from the previous job finds its way onto the wall, it could interfere with the plaster’s ability to stick to the wall or set properly. Use cold water, let it soak in and mix as little as possible if you want the plaster to set slowly. Use hot water and mix a lot if you want the plaster to set very fast.
Plaster can also damage or scratch wood or laminate floors, so be sure to cover your floors well. For airtight protection, use painter’s tape to secure the dropcloth directly to the floor beneath the wall. When you’re finished, just roll up the drop-cloths, take them outside, and spray them clean. The biggest cause of plaster falling off of the tools is mixing in too much water. As you get better, you will drop less plaster, you will get less on your hands and cleanup will be less.
Prime over stained areas to ensure the plaster will adhere properly. Repair any cracks in the wall before plastering it. Make sure the wall and ceilings are plumb and flush before you start plastering. Otherwise, there may be bumps and indentations on the finished wall. [3] X Expert Source Nick YahoodainGeneral Contractor Expert Interview. 6 October 2020. To test whether the wall is ready to accept new plaster, run your finger over the surface. If it comes away caked with dust, it still needs some work. Spraying the wall with water will help the new plaster to adhere to the old wall. You should always begin by cleaning your work surface, whether you’re resurfacing an old wall or plastering over brand new lath. Dust, soap, oil, tar and mold all cause the plaster not to adhere to the surface. Also a wall that is too dry causes the water to be absorbed out of the plaster and set before it has time to stick to the wall.
PVA glue is necessary to help the new plaster adhere to the wall. A preliminary coat will also prevent the substrate from leaching moisture from the plaster, which can cause crumbling.
Always add the plaster mix to the water, not the other way around. If you add water to the plaster, you will have to apply pressure to mix the plaster at the bottom of the pail and you will over-mix the plaster and it will set too fast to work with. Stir the mixture as you add in the plaster. An electric drill with a paddle attachment can save you a lot of time if you’re mixing up large or multiple batches. You must know that mixing the plaster with an attachment on your drill will cause the plaster to set much faster. Use the attachment for large jobs, where you will apply a lot of plaster in a short amount of time. If you are doing small patch-work, use a smaller bucket and mix by hand so that the plaster will set slower and give you time to work.
A good way to determine whether the plaster is thick enough is to stick a wooden paint stirrer straight down into the bucket. If it stands up on its own, it means your plaster is just right. [6] X Research source
When properly mixed, the plaster shouldn’t stick to the hawk. If you want, however, you can wet the hawk slightly to help it release.
Start with a conservative amount of plaster and add more as needed. It’s much easier to build the coat as you go than it is to even out an oversized glob.
If the plaster is soft and slides down a little on the wall, let it set 5 minutes to harden a little, then hit it with the trowel again and it will not slip. Keep your trowel at a slight angle. Holding it flush can pull plaster away from the wall. For the first coat, aim for a thickness of roughly 3/8” (1cm). [9] X Research source
You may need a step ladder to hit the upper corners of the wall. Don’t worry too much about getting the thickness perfect at this point. You’ll be going back over the plaster later to smooth and polish.
If necessary, use a spray bottle to re-wet the first sections of plaster. This will make them respond better to the trowel. [12] X Research source A wet high-quality paintbrush can come in handy for touching up tricky edges and corners.
If you don’t have access to either of these tools, you can also use an ordinary fork, though this may take quite a bit longer. Scoring creates shallow grooves that increase the overall surface area of the wall and allows the second coat to adhere better. [14] X Research source
You can smooth the skim coat with your trowel or trade it out for a float to take care of the finishing touches.
Take your time. Smoothing plaster is a painstaking task, but one that is important to do correctly. Be careful not to polish the plaster too much. Eventually, it will begin to take on a glossy quality, which can weaken the hold of paint and wallpaper.
Factors like the composition of your plaster, the temperature of your work area, and the amount of moisture in the air can all have an impact on drying times. The wall should be totally dry before you add paint, wallpaper, or any other decorations.
