Seamless interior walls start with a well-mixed plaster. When mixing your own plaster for home improvement projects, it's important to remember to work quickly, as you'll essentially be racing the clock before it sets. Start by adding the powdered plaster to the water bit by bit until you reach the desired thickness. You can then use an electric drill mixer to work out lumps and inconsistencies and achieve a perfect smooth consistency.
Steps
-
Prepare the wall for plastering. Before you get started, make sure the wall you're finishing has already been taped and sanded, and any seams have been touched up with a base coat. That way, all you'll have to worry about is spreading the plaster, which will require your full attention. [1] X Research source
- Plaster is best applied to wood or metal lath, or bare walls stripped of paint and wallpaper. If the wall has semi-gloss or gloss paint on it, you should prime it before adding plaster. [2] X Research source
- Use plastic sheeting and painter's tape to cover areas you don't want plastered.
-
Protect your work area. Working with plaster can get pretty messy. To safeguard your surroundings and avoid an extensive cleanup process later on, it's a good idea to lay down a drop cloth or tarp. Make sure you have all the tools and equipment you need on hand to avoid wasting valuable time searching later on. [3] X Research source
- Consider putting on a change of old clothes that you don't mind getting dirty.
- It can also help to wear a respirator and eye protection, if you're sensitive to dust.
Advertisement -
Set a large bucket outdoors to do your mixing in. It's best to mix plaster outdoors to minimize cleaning up the splatter from the mixing paddle. [4] X Expert Source Ryaan Tuttle
Home Improvement Specialist Expert Interview. 24 September 2021. The exact size of the bucket you'll need will depend on the amount of plaster you're preparing. In most cases, however, a 5 or 7 gallon (18.9 or 26.5 L) bucket will be ideal. If you're using a smaller bucket, you may have to work in batches. [5] X Research source- Keep in mind that plaster expands, so it's better to have a couple more gallons (around 7 L) worth of room than you need just to be on the safe side. [6] X Research source
- Hose out the bucket to flush away sediment and other residue if you've previously used it for other projects.
-
Fill the bucket with clean water. Add 1–2 gallons (3.8–7.6 L) (3.8-7.6L) of room-temperature water. [7] X Expert Source Ryaan Tuttle
Home Improvement Specialist Expert Interview. 24 September 2021. It's essential that you add the plaster to the water, not the other way around. This will help prevent troublesome lumps and give you more control over how thick the mixture turns out. [8] X Research source- If the water is too cold, it can make the plaster harder to mix. If it's too warm, it may cause it to set prematurely. [9] X Research source
-
Add plaster to the water gradually. Scoop out a small amount of plaster from the bag using a plastic cup and dump it in the bucket. Generally, you'll want to use approximately a 1:1 ratio of plaster to water—in other words, half and half. However, you should add only about half of the plaster at this point as more will be added later. [10] X Research source
- Try not to take more than a couple minutes to sift the plaster, or it will begin to set. [11] X Research source
- The plaster will need to soak for 2-3 minutes before you begin mixing.
Advertisement
-
Attach a paddle mixer to your drill. You'll get the best results with a corded mixing drill, as these offer the distance and convenient control you need to work comfortably. Thread the end of the paddle into the drill, making sure the joints fit together correctly. Run the drill for a few seconds at a low speed to check that the mixer attachment is secure.
- Wire cage-type mixers can cut through clumps rather than just push them around. [12] X Research source
-
Mix the plaster thoroughly. [13] X Expert Source Ryaan Tuttle
Home Improvement Specialist Expert Interview. 24 September 2021. Lower the paddle into the plaster to the bottom of the bucket and switch on the drill. As you mix, raise and lower the paddle and swirl it in both a clockwise and counterclockwise direction. This will help the blades hit the plaster from as many different angles as possible. [14] X Research source- Set your drill to a slow speed to prevent splashing. [15] X Research source
- Aim to mix the plaster for 1 to 2 minutes, or just long enough to wet it throughout.
- Scrape the sides and bottom of the bucket periodically with your trowel to loosen dry, stuck-on bits.
-
Add more plaster to achieve a thick, smooth texture. Cut off the drill and add a small amount of plaster into the bucket, then resume mixing to incorporate the fresh plaster. Continue sifting and mixing until the plaster is roughly the same consistency as peanut butter. [16] X Research source
- A good rule of thumb is to only add about half the amount you originally used on follow-up mixes. [17] X Research source
- Sifting the plaster by the handful may be more precise than pouring straight from the bag as you get closer to the optimal texture.
- Rinse off splatter or plaster powder from your surroundings before it dries.
-
Test the thickness of the plaster. Let the plaster sit for a few minutes after you're finished mixing. At that point, the plaster should be thick enough to heap onto the trowel without running off. Another useful test is to route the top of the mixture with your trowel and watch for it to fill in gradually—thin, soupy plaster will puddle instantly, while you may not notice any change in overly thick plaster at all. [18] X Research source
- If you accidentally thicken the mixture too much, you can add more water to thin it out.
Advertisement
-
Avoid under- or over-mixing. Keep your mixing time to no less than 1 minute and no more than 2. When plaster isn't properly mixed, it has a tendency to separate. On the other hand, overmixing can cause bubbles to form, which may decrease the strength of the plaster or ruin the smoothness of the finished wall. [19] X Research source
- Perfectly-mixed plaster will be opaque, creamy, and free of lumps, bubbles, or grit.
-
Add pigment for bolder colors. A splash of vibrant color can make walls pop. Stir dry powdered pigment into a container of water to create a slurry, then add the slurry to the plaster bucket just prior to mixing. This will make for effortless blending and help you sidestep common issues like spotting and clumping. [20] X Research source
- When incorporating pigment, you can add up to 10% of the total weight of the plaster you used, or until you reach the desired depth of color.
- Colored plasters allow certain paint shades to show up better. For instance, royal blue paint will stand out boldly over a blue-tinted plaster base without the need for as many coats of paint as you would need for plain white plaster.
- They can also be quite attractive on their own, providing a more earthy, natural look to a room. [21] X Research source
-
Apply the plaster right away. Once it's been mixed, pour the plaster onto a damp spot board to prepare it to be scooped onto a hawk. [22] X Expert Source Ryaan Tuttle
Home Improvement Specialist Expert Interview. 24 September 2021. Depending on the working time of the plaster, you'll have somewhere between 5-45 minutes to get it onto the wall before it begins to harden, so don't delay. For best results, always mix your plaster just before you smooth it on. [23] X Research source- Plaster spreads and sticks best when it's fresh.
Advertisement
Expert Q&A
Ask a Question
200 characters left
Include your email address to get a message when this question is answered.
Submit
Advertisement
Tips
- Plaster comes in different working times, such as 5, 20, and 45 minutes. Choose the 45-minute kind if you're new to using plaster.Thanks
- Only mix the amount of plaster you can use within the working time. Otherwise, it will set prematurely and you will have difficulty getting it out of the bucket.Thanks
- Using water that's slightly on the cool side can increase the amount of time you have before the plaster sets, which may be useful if you're inexperienced with working with plaster.Thanks
Submit a Tip
All tip submissions are carefully reviewed before being published
Thanks for submitting a tip for review!
Advertisement
Warnings
- If possible, avoid scheduling your plastering projects on hot days. Heat and humidity can affect the plaster's ability to set correctly.Thanks
Advertisement
Things You'll Need
- Large bucket
- 50-lb (23-kg) bag of plaster
- Clean water
- Corded electric drill with mixing paddle attachment
- Plastering hawk
- Hand trowel
- Drop cloth or tarp
- Painter's tape
References
- ↑ https://www.thisoldhouse.com/how-to/how-to-plaster-wall
- ↑ https://www.bobvila.com/articles/462-how-to-rebuild-a-wall-with-three-coat-plaster/
- ↑ https://projects.truevalue.com/paint/interior/general_repairs/plaster_wall_repairs.aspx
- ↑ Ryaan Tuttle. Home Improvement Specialist. Expert Interview. 24 September 2021.
- ↑ https://www.americanclay.com/3-mixing-your-plaster
- ↑ https://www.youtube.com/watch?v=SAYEA94brfs
- ↑ Ryaan Tuttle. Home Improvement Specialist. Expert Interview. 24 September 2021.
- ↑ http://www.masteringplastering.com/mixing-plaster/how-to-mix-plaster.php
- ↑ https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/plastering-technical-guide-mixing-veneer-plaster-and-decorative-interior-finish-en-PM9.pdf
- ↑ https://www.americanclay.com/3-mixing-your-plaster
- ↑ https://ceramicartsnetwork.org/daily/pottery-making-techniques/making-ceramic-molds/plaster-mixing-101-how-to-mix-plaster-for-ceramic-molds/
- ↑ https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/plastering-technical-guide-mixing-veneer-plaster-and-decorative-interior-finish-en-PM9.pdf
- ↑ Ryaan Tuttle. Home Improvement Specialist. Expert Interview. 24 September 2021.
- ↑ https://www.youtube.com/watch?v=SAYEA94brfs
- ↑ http://www.masteringplastering.com/mixing-plaster/how-to-mix-plaster.php
- ↑ https://ceramicartsnetwork.org/daily/pottery-making-techniques/making-ceramic-molds/plaster-mixing-101-how-to-mix-plaster-for-ceramic-molds/
- ↑ http://www.masteringplastering.com/mixing-plaster/how-to-mix-plaster.php
- ↑ http://www.masteringplastering.com/mixing-plaster/how-to-mix-plaster.php
- ↑ http://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/plaster-mixing-procedures-application-en-IG503.pdf
- ↑ https://www.americanclay.com/3-mixing-your-plaster
- ↑ http://www.architecturaldigest.com/story/easiest-wall-decor-idea-is-leaving-them-unfinished
- ↑ Ryaan Tuttle. Home Improvement Specialist. Expert Interview. 24 September 2021.
- ↑ https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/plastering-technical-guide-mixing-veneer-plaster-and-decorative-interior-finish-en-PM9.pdf
About This Article
Thanks to all authors for creating a page that has been read 78,248 times.
Advertisement
100%
of readers found this article helpful
.
Click a star to add your vote
% of people told us that this article helped them.
