Joint compound is used not only for drywall hanging but also for wall texturing. It is often helpful for finishing gypsum board joints, corner trims, and skim coatings. Additionally, it is great for repairing minor scratches and damage to walls.
The simple answer to whether you can put joint compound over paint is yes. The substance can be used on painted walls, but little preparation is required to ensure that the plaster adheres to the wall. Once dry, you can paint the joint compound with latex paint and glaze it to give it dimension. Make sure this is the look you want before applying the texture to the wall. Also, bear in mind that removing joint compound texture can be very difficult.
How to Apply Joint Compound on a Painted Wall
Here is a list of the things you will need for proper application:
- Paint scraper
- Drywall primer
- Paint roller
- Drywall joint compound
- 4-, 6- and 8-inch drywall knives
- Paper drywall tape
- 120-grit sandpaper
- Work light
1) Clean wall
First, you want to make sure the walls are clean and free of dirt before applying drywall mud on them.
Wipe the wall with a damp sponge and remove cobwebs from the room’s corners. You should also clean away accumulated dust along skirting boards and trim.
After cleaning the wall, lightly sand to create a surface for the plaster to adhere to. This is especially important if the current paint on the wall has a glossy surface. Sand the wall with medium-grit sandpaper and use a sanding rod if necessary. Wear safety goggles and a dust mask to protect yourself against toxic substances during the process. After sanding, wipe the wall with a sponge to remove dust.
Use a roller or trowel on the joint compound. A large paint roller will be heavy with plaster, so you will need to use a smaller one. If you are using a trowel, spread the plaster over the trowel and hold the tool’s end against the wall.
Wipe off the plaster on the wall to give it a texture. You may have a preferred texture but still, it should look the same across the wall. Covering the entire painted wall is not necessary, so cover only about 85%. When painted and glazed, the areas that are not structured would look like the “lower” parts of the texture.
- The plaster should be moist and should not have hard lumps in the mixture.
- If it is difficult to apply, add a little quantity of distilled water and mix. Use a hand drill that has a plaster mixer (squirrel mixer) attached to it.
- We recommend using lightweight joint compounds instead of regular ones. Lightweight variants do not crack easily when dry.
What Types of Joint Compounds Can You Put Over Paint?
1) All-purpose Compound
Expert drywall installers may use different types of mud at different stages of the process. For example, some pros use one type of mud just to embed the paper tape, another type to set the base coat over the tape, and another mud to cover the joints.
All-purpose compound mud is usually premixed and sold in buckets or boxes. It can be used in all stages of drywall; for embedding joint tapes, finishing coats, texturing, and filling. Its lightweight and slow drying time make it very easy to work with and a good option for DIY enthusiasts to coat drywall joints’ first three coats. However, this type of joint compound is not as powerful as some other types like topping compounds.
A special form of the all-purpose compound is the lightweight all-purpose mud. This is similar to the normal all-purpose mud but has lighter weight. Some experts believe that due to its low binder content, it is inferior for seam bonding. A lightweight all-purpose mud may be used to finish a seams’ first and second coat and bead corners. It is also easy to sand.
2) Topping Compound
Topping compound is the best mud to use after applying the first and second coats of taping compound to taped drywall joints. The topping compound is a low-shrinkage compound that applies smoothly and provides very strong adhesion. It’s also very easy to work with.
Topping compounds are usually sold as dry powders that are mixed with water. This allows you to prepare as much as you want, although it’s less convenient than a pre-mixed mix. The remaining dry powder can be saved for later use. However, the topping compounds are also sold in pre-mixed boxes and buckets, so you can buy the type you prefer.
A top coat is not recommended for laying joint tape, which is the first layer of most drywall joints. When used properly, the topping compound should reduce sanding time compared to lighter mixes like all-purpose mud.
3) Taping Compound
As the name suggests, this compound is best for embedding joint tape in the first stage of finishing the drywall joint. It does not dry as easily as regular joint compounds and is difficult to sand. It is also a great option when you need to cover plaster cracks or when you want good adhesion and crack resistance around door and window openings. You can use this mud for laminating sheets of multi-layer partitions and ceiling drywall.
4) Quick-Setting Compound
Commonly referred to as “hot mud”, this fast-drying compound is great for when you need to get the job done quickly or want to apply several coats on the same day. The quick-setting compound can also be used to fill deep cracks and holes in drywall, which can be valuable when drying time is an issue.
If you are working in areas with high humidity, consider using this compound for a good drywall finish. It hardens through a chemical reaction instead of simply evaporating water like other compounds. This means that quick-setting compounds are still effective under humid conditions.
Quick-setting mud usually comes in the form of a dry powder that needs to be mixed with water or used at once. Follow the manufacturer’s recommendations before use. It is available in various setting times, ranging from as low as 5 minutes to a set time as high as 90 minutes.
Will Applying Joint Compound Make the Painted Wall Waterproof?
In the bathroom, you can use regular joint compounds. However, a normal joint compound is not waterproof, so you may want to apply waterproof paint over the compound. Applying a top coat of waterproof paint creates a barrier between the moisture in your bathroom and the joint compound.
Do I Need to Apply a Primer Before Applying Joint Compound Over Paint?
If you must use drywall mud on a painted wall, it can be easily done on a flat surface or a surface that has been painted with eggshell paint. Usually, applying a primer on a painted surface before adding the joint compound is not necessary. Joint compounds adhere well to many surfaces and do not require a primer for adhesion.
Use a wide drywall knife to apply the compound as evenly as possible to reduce the number of marks left. However, for a seamless working process, once the wall is painted with either a satin, gloss, or semi-gloss finish, you can apply primer to the areas that need to be drywalled. Primer provides a matte finish to which joint compound adheres.
Can You Put Drywall Mud Over Paint?
Drywall mud is just another name for joint compound. It is mainly composed of gypsum and limestone, but also contains other materials such as starch, clay, perlite, and mica. Joint compound has a spreadable consistency that is like mud, hence the common name. However, this consistency also depends on the kind of joint compound.
What is the Difference Between POP and Joint Compound?
Plaster of Paris is gotten from calcium sulfate dehydrate. Joint compound on the other hand is made from a combination of Portland cement, gypsum as well as limestone. Joint compound can also come in a powdered or pre-mixed form and comes in a variety of colors that you can use on your walls.
Now you know the different types of joint compounds and what each of them is commonly used for, so choose the best option for your project. Also, follow our guide on how to apply joint compound over a painted surface and you are good to go.
Remember to use the appropriate tools during your project to get the best results. Feel free to do more research on other related topics including applying joint compounds on other surfaces, if you need to compare application procedures.
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