Attach grit sand paper. In the corners of the room you can use a sanding block or we sometimes use a Festool DTS hooked up to our Festool Vacuum. Defects may show as shadows that need further sanding to get a flatter ceiling or wall. Submit a Comment Cancel reply You must be logged in to post a comment. Articles Search for:.
Phone The primer seals loose paper and promotes better adhesion of the joint compound. Patch these problems with setting-type joint compound. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content What is Skim Coating? Do you have to skim coat? Is skim coating necessary? What do you use to skim coat a wall?
Otherwise you'll have to climb up and down a ladder all day long. Stilts significantly simply the operation. Plus they make for great facebook pictures. For sanding a pole sander with sanding screens will provide the necessary leverage. For large areas it is more important to go through the different grits of sanding paper.
Otherwise you'll tire out too fast. A powered drywall sander such as the Porter-Cable produces the fastest and cleanest results. These tools really do work. Bare drywall or other joint compound are the ideal surface for applying a skim coat.
All you have to do is make sure the area is mostly dust free. Painted walls with flat paint can be coated directly. Clean all surfaces thoroughly with TSP and water. While the skim coat will adhere to the flat paint just fine, you are taking a risk that some other layer below the surface will fail. The walls in older homes have been painted dozens of times. Who is to say that that 20 year old layer of primer 5 levels down will hold another 20 years.
Walls with any sort of sheen will have to be either stripped, sanded, or covered with a bonding agent. Don't try to skim coat a surface like this without doing the prep work. The plaster will come off. As a first-timer you have to prepare to apply at least 2 coats over the entire ceiling, sand once, and fix defects a couple of times.
Professionals with years of experience can do better. Speed should not be one of your goals. Even someone who has never worked with drywall can achieve a perfect result with patience and tenacity. The first coat is the rough coat. It needs to cover the entire ceiling and fill in the big defects in the ceiling. This coat is relatively hard to level, because it is the thickest. Imperfections created by errand trowel strokes will be numerous.
Don't let yourself be discouraged. The wall will look rough after the first coat. It's second coat that yields all the results. Let the first coat dry overnight. Bigger mistakes, mistakes with pronounced edges, will be easier to scrape off. There are two types of joint compound that can be used for skim coating: setting-type joint compound and ready-mixed joint compound. Setting compound is a powder that sets to a very hard finish when mixed with water, similar to the way concrete sets.
It comes in setting rates of a few minutes to an hour or more. Ready-mixed joint compound comes wet and ready to use out of the bucket. It takes several hours to dry and is soft compared to setting compound. Which compound to choose depends on the surface to be skimmed. For most major damage, the best choice is setting compound. This would include any water-damaged plaster or drywall, and very rough surfaces like drywall textures that will require several coats of mud to smooth out.
Use ready-mixed compound for finishing drywall and for minor wall imperfections requiring one or two coats to cover. Ready-mixed is also good for the final coat over any skim coating job.
It's easier to spread than setting-type, allowing for a thinner application and it's soft, making a smooth finish easier to achieve when sanding. Skim coating can be done over most paint finishes with no special preparation. As long as the surface is ready for repainting, it will also be ready for skim coating. However, if the surface has been damaged, exposed to water or if you have a very shiny paint to cover, some preparation will be necessary to ensure no bubbling develops in the finish when you're done.
Use a mud pan to mix small amounts of mud at a time for skim coating. Use a 2 to 1 ratio of powdered compound to cool, clean water. To be sure you can use the mud before it sets, start with about a cup of powder. Add about a half cup of water and mix the mud so it's thick enough to remain on a joint knife when held upside down.
If your mixture is too thin and soupy, add a little more powder until you get the right consistency. This type of joint compound will set quickly, so use it right away. Collect the wet mud onto one side of the pan, scooping it up with the knife and scraping it onto the rim.
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