When it comes to achieving a smooth, flawless ceiling finish, the challenges can be even greater than with walls. In medium to high-end construction, where flat, smooth drywall ceilings are preferred, ensuring an even texture can be difficult, especially under critical lighting conditions. This post explores common issues faced during ceiling painting and provides best practices for ensuring optimal results, whether you're using traditional methods or exploring alternatives like high-solids latex basecoats. Here's how you can tackle ceiling imperfections and achieve a seamless finish even under challenging conditions.
The Challenge of Achieving a Smooth Ceiling Finish:
Back in the day, ceilings were often finished with spray textured surfaces consisting of polymeric binders or modified plaster and aggregate to create a “spatter” effect. This helps hide flaws in the finish that otherwise might be quite visible. But nowadays, especially in medium to high-end construction, many owners and architects prefer a flat, smooth drywall ceiling surface.
We’ve discussed the challenges of obtaining a satisfactory finish with new drywall on a few occasions, so it is probably no surprise that achieving a smooth, defect-free finish on a ceiling can be even more difficult. These defects are caused by a variation in texture and porosity between the paper coating and the drywall filling compound (paper absorbs the applied coating at different rate than the filling compound, creating an uneven surface). Generally, defects in a ceiling’s finish are only visible when viewed at an angle. Lower ceilings tend to make ceiling defects more visible as the viewing angle becomes more acute.
Critical lighting conditions caused by either natural light from windows or from ceiling-mounted fixtures can exacerbate the problem. It is important to perform the final inspection after setting up the permanent lighting conditions for the space to determine which defects will be visible once the project is completed. If inspection occurs when lighting is lower than the permanent conditions of the space, “new” surface defects will become visible once brighter lighting is installed. If inspection work occurs with when lighting is brighter than the permanent conditions of the space, time and money could be wasted repairing defects that will be invisible upon completion of the project. The following list of best practices outlines a few tips for optimizing ceiling painting projects.
Best Practices for Painting Ceilings:
- Optimal results are more likely to be achieved if the specification requires an ASTM Level 5 drywall finish
- Even if the initial finish was sprayed, the spec should require backrolling the ceiling finish. The stipple pattern of the roller can help to hide the underlying texture variations in the drywall. A ½ inch (15 mm) nap roller may offer the best and most efficient results.
- Very large ceilings are finished in phases, and it’s not reasonable to get all the paint from a single batch as is generally advocated for wall coating work. Consequently, the spec should also require the painter to “blend back” the finish of each new section by shading the new topcoat back over the previous section with a spray gun. With a flat finish, this can effectively prevent a noticeable difference between sections finished at different dates with material from different batches.
A Level 5 Alternative for the Painter:
Industry standards and MPI generally advocate specifying an ASTM Level 5 drywall finish (application of a skim-coat of drywall compound across the entire drywall surface) to help assure a satisfactory paint job for a ceiling or wall, especially in critical lighting conditions or when using non-flat finishes. Although a Level 5 finish generally produces better results than the more commonly specified Level 4 finish, it does not guarantee a flawless finish. Many drywall finishers lack the skill or experience to properly apply a Level 5 finish, and most projects do not budget for the increased expense of a Level 5 finish.
So if a Level 5 finish is generally not practical for most projects (budget, skill of drywall finisher), what can a painter do to achieve a flawless finish when painting a new ceiling?
This inspector found himself in this situation when it came time to paint the new drywall ceiling in the remodeled main floor of his house. After seeing enough ceilings with seams telegraphing through the finish he considered applying a Level 5 finish over the new drywall. Although the inspector was an accomplished painter, he did not have skill or experience to achieve a satisfactory Level 5 finish.
ASTM’s Level 5 Drywall finish standard states that “a thin skim coat of joint compound shall be trowel-applied to the entire surface…As an alternate to a skim coat, a material manufactured especially for this purpose shall be applied.” Although some “spray-on” skim-coat products are available, his experience with these products found that they tend to develop air bubbles when sprayed and break-off or crumble when sanded.
With this in mind, the inspector was hesitant to try another alternative product, which was a fast-drying sandable high solids latex basecoat designed specifically to minimize the surface differences between wallboard facepaper and joint compound. The inspector decided to test it on a wall section. He mixed and strained the material and even though the material was quite heavy in weight and viscosity, he did not want to thin it.
After applying the product, the paper texture was filled, the surface was quite smooth, and the basecoat had excellent adhesion. Encouraged by the test patch, the inspector sprayed out four gallons of material across the 1100 square foot ceiling. After it dried, he scuff-sanded the surface with 120 grit paper on a pole sander and learned a valuable lesson: since the material was quite hard, heavy sanding was difficult, and the best results were obtained where the product was applied in a smooth, consistent pattern.
He then sprayed one coat of a high quality latex drywall sealer and two coats of a product approved under interior flat latex. Both the sealer coat and the finish coats were backrolled to push the coatings deep into the substrate, as well as to produce a roller stipple to help hide the underlying texture variations of the drywall. Additionally backrolling the finish coat means that touch-up work can be applied with a similar nap roller instead of by spray, since touch-up work should always be applied in the same method the original finish was applied.
This resulted in a very smooth, flat ceiling that shows no signs of visible underlying paper texture or seams even under critical lighting conditions. The combination of the high-solids latex basecoat and flat latex finish produced one of the best finishes on a drywall ceiling the inspector has ever seen, which leads him to conclude thus: given the right products and tools, a smooth, flat finish can be attained by painters over a Level 4 drywall finish.
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