Mixing joint compound for your drywalls often requires high efficiency and precision.
Most times, you may have done all you should do but still find those tiny little blisters or bubbles on your drywall after skim coating it.
It could get bothersome and frustrating, leaving you to worry and continuously ask yourself: How do I mix my joint compound without bubbles?
Joint compounds can be mixed without having bubbles. Especially if you thoroughly mix the mud to a consistent texture, add a little water to the compound to enhance adhesion, add extra layers of mud when skimming, sand the area on your drywall where you are skimming, and prime the walls with oil primers or sealers.
How Do I Mix Joint Compounds Without Air Bubbles?
Joint compound on drywalls is mainly for the repair of damaged walls with holes, cracks, blisters, fish eyes, and even bubbles.
All these can be done away with if the joint compound is carefully and adequately mixed before use on walls. Interestingly, it is achievable if you follow some laid down procedures such as:
#1. Priming The Coat
Priming helps blend the joint walls with the compound to create a uniform and bubble-free surface, which means that priming is done in the mixing stage of the compound.
Before mixing the compound, use oil-based or water primer to prepare the wall for your painting. However, allow the primers to dry off before you begin to skim coat.
Then, you can use a paint roller or brush to spread the primer evenly on the walls as much as you can avoid priming directly on the walls just before you skim coating.
This will cause a weak adhesive force between the walls and the primer, mainly oil-based primers.
#2. Thoroughly Mixing The Joint Compound
As you already know, joint compounds come in either premixed or dry forms. The dry mud form is much more challenging to use as it requires more delicacy when using it to skim coat.
Most times, they take you a lot more time to prepare. However, to avoid bubbles forming on your drywall after a painting job, ensure that you thoroughly mix your mud to remove every form of air or blister.
Also, occasionally add a pinch of water when painting each time you notice the mud has become too thick.
Always resist the temptation to rapidly stir your mud instead, do it gently and slowly for just a short duration of time.
#3. Sanding The Walls
Firstly, when sanding a wall, ensure that the room with the patched or rough wall is appropriately sealed or shut to prevent the coat from getting all over the place.
Next, ensure that you carefully sand out all holes, bubbles, and fish eyes until there is none on the wall.
When you sand a particular wall area, you make it smooth and ready for priming. You will need safety goggles to protect your eyes.
For thicker mud, you can use sandpaper to smooth the walls and a wet sponge to remove all excess mud if the walls are already smoothened.
#4. Cleaning The Walls
After skim coating your walls, always clean out the dust on the walls that are created when sanding.
First, make sure that the dust and nubs are cleaned out. This requires vacuuming the floors and wiping the walls with a damp microfiber cloth or sponge.
Next, ensure that every angle on the wall is thoroughly cleaned and all dust removed for a sleek look.
Finally, a smooth and clean wall is essential for removing every form of blisters and bubbles.
Why Am I Getting Air Bubbles In My Joint Compound?
As a homeowner, the primary reason for skim coating your drywalls is to give them a great and sleek appearance.
However, you may notice from time to time that your joint compound has tiny bubbles when you use them to skim coat your walls.
This may leave you wondering most of the time what the cause of air bubbles in your joint compound is. Nevertheless, here are a few reasons.
#1. The Mud Has Lost Its Adhesive Force
When mud loses its adhesive force, it blisters. This causes the mud to peel off faster than when it should.
As a result, air and water-filled bubbles begin to form eventually. As they dry on the walls, some bubbles pop on their own—some dry up while others get hardened.
Oil-based primers and sealers are highly recommended to help curb this. It may not be a hundred percent efficient, but it can help to hold in your skim coat for a few months or longer.
#2. Dirty Surfaces
Before painting a wall, cleaning out walls to remove dirt, dust, and grime is essential. It should always be the go step for every of your skim coating projects.
Dirt has a way of clinging to walls over time, which is why before you coat your wall, cleaning is essential.
Dirty surfaces are bound to form air bubbles and push out on the walls when the joint compound gets dried.
To remove dirt, always scrape out old and dusty mud before you start to skim coating. Then, use a wet and soapy cloth to thoroughly clean out the dust and allow it to dry before you begin to skim coat.
#3. Wrong Application Of Primers And Sealers
It is expected that once you have applied primer to your joint compound, ensure that you continuously apply it to all of your subsequent skim coating jobs.
This is because plaster and drywalls are more liable to absorb the pigments of primers and sealers, which mean that your next skimming job will require you to use a lesser amount of primer on your drywall.
Hence, once a new mud is applied to a wall, it is expected to stick automatically due to the former primer applied.
However, there is a chance that your primer may have lost its adhesive force on the walls, which may result in bubbling or blisters.
As soon as you notice bubbles on walls after you have done a primer-free wall coating, ensure to scrape out all affected areas, clean out the surfaces with a damp cloth to remove the mud then apply your primer.
You can choose to go with a latex or oil-based primer depending on the type of joint compound you are using.
However, oil-based primers are much more efficient than latex primers. Also, always remember to let the primer dry out ultimately before you start coating your drywall.
If not, the solvent in the primers will not evaporate as it should if you coat the walls too soon.
It can also lead to air traps which will eventually become trapped underneath the walls resulting in blistering and bubbling.
#4. Moist Walls
When there are excess moistures on soon-to-be skim-coated walls, it could result in water-filled bubbles in your joint compound.
Water-filled bubbles are primarily formed in kitchens around the sink, bathroom, and basement.
The basement has low ventilation, while kitchens have excess water and constant condensation. The excess moisture can be from water droplets, leaks, condensation, and high humidity.
#5. Scorching Environments
As excess cold and moisture ruin the joint coat, so does heat. In addition, excess heat and sunlight can result in uneven dryness in the mud, thereby leading to bubbles or blisters under the surface.
However, it is vital to look through the owner’s manual for the proper room lighting of your room when skim coating.
However, permanently close the window and doors when skimming to prevent direct sunlight from heating the walls.
Also, ensure that the temperature in your room is not above 85 degrees and not below 50 degrees.
#6. Inappropriate Roller Cover
Roller covers vary in size and shape and are chosen based on the space you want to cover at a particular time as you skim coat.
For example, using a short roller cover for a lengthy area could lead to rough edges on the walls and eventually blisters and bubbles.
For drywalls, the ideal size of one to one and a half or one and a quarter inches long.
What Causes Fish Eyes In The Joint Compound?
Fish eyes are primarily caused by grease or oily surfaces and even silicon particles deposited on the joint compound as you skim coat.
However, little airborne droplets can also cause them. For instance, a contaminated surface with wax, oil, grease, or silicon will develop fish eyes when coated.
Fortunately, fish eye eliminators remove the fish eye from joint compounds. Fish eye eliminators are silicone surfactant products.
When applied to the fish eyes, they dissolve it by relaxing the tension between the joint compound particles in three easy steps.
| Steps | Procedures |
|---|---|
| Scrap Out Wet Paint | Once you notice a fish eye on your joint compound, remove the wet paint by scrapping it or using water to clean the mud and refinish it. |
| Add Fish Eye Eliminator | Next, add the fish eye eliminator over the affected area and spray it with water. |
| Spray Mist Coat | Sometimes, the fish eye may pop out in the base coat. When this is the case, spray a mist coat over the area where the fish eye appeared and allow it to dry out on its own. |
Why Do Bubbles Form After Priming Over Joint Compound?
Most times, bubbles form on walls when they are underlying unresolved issues. Joint compound forms blisters even when the force of adhesion between the walls weakens.
Other factors for why bubbles appear on walls after priming are:
- Priming on very wet, rough dirty, or damp surfaces or in areas with high humidity
- Priming on hot, drywalls or walls exposed to heat and sunlight
- Using the wrong primer on walls. For example, using oil-based primers on latex paints.
Can You Prime Over Joint Compound?
Of course, you can prime over joint compound. There are two types of primers: oil-based primers and water-based or latex primers.
The primers help create study surfaces of your joint compound and reduce the chances of having recurring blisters or bubbles on your walls.
It also gives a uniform surface to your walls and may not require adding extra layers of mud to your wall for better protection.
When applying primers to walls, allow them to dry thoroughly and keep away from hot, damp, and cold environments.
Also, ensure to use the proper primer or sealer for better results. Primers are applied to walls using a paint roller, while very tight corners may require you to use a small hand brush.
Conclusion
Joint compounds require precision and delicateness during installation. However, no matter how careful you may be, your joint compound may still develop bubbles, blisters, and even fish eyes.
In this article, I outlined why your joint compound has bubbles when skimming coat and primer, how to get rid of bubbles on your joint compound bubbles, the causes of fish eyes, and the steps to get rid of them.