Chapter 6: Tape and Texture
During the 20+ years while working with our partners in the Factory Built Housing (FBH) industry, we’ve received occasional comments or complaints regarding poor uniformity of applied texture. These comments are most often directed to the following areas: banding of wall and ceiling mudded joints, and shadowing and/or streaking. Here you will learn more about these conditions, and best practices for tape and texture processes.
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Banding and Shadowing
Identify the Source of the Problem
Banding and shadowing/streaking are conditions that are most evident following paint application, and are often mistaken as paint problems. In many cases, these issues are the result of the tape and texture processes.
To identify the source of the problem, apply an additional coat of paint. If the issue remains, most likely it is due to a flaw in the mud/texture process, and not an issue with the performance of the paint.
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Defined
Banding
When mudded joints and seams are highlighted and stand out, this is referred to as “banding.” The joints and seams appear darker or shadowed, and can be more pronounced when viewed from an angle. Banding occurs most frequently and is most noticeable on ceilings, due to the ceiling’s large surface area.
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Common Cause
Banding
Banding is most often the result of the surface reaction between “hot mud” and texture. As it cures, hot mud consumes moisture. Conventional joint compound materials (including texture) and paint expel moisture during the curing process. This creates a condition during the curing process in which the hot mud consumes moisture from the texture and paint. As a result, the texture material fractures and appears rougher than the texture applied to the surrounding smooth field of the drywall.
Banding is almost guaranteed to occur in a closed, humid curing environment in which the temperature is below 50°F (10°C) for either the ambient or surface temperature, or both.
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The Best Practice Solution
Banding
Allow “hot mud” to cure as quickly as possible. This can be achieved by exposing the hot mudded area to heat and air movement, preferably dry air. Application of a quality primer-sealer after the mudding and before applying the texture reduces the potential for banding. This process allows any uncured hot mud to consume moisture from the primer, not from the texture. The primer will help to provide a more uniform base, allowing the texture to cure more evenly.
A “kiss” coat (fog coat) over the mudded area alone, will help to unify the field with the mud. Since texture lays down differently on smooth surfaces versus rough surfaces, providing a more uniform primed surface from field to joint areas also reduces the potential for any noticeable variation in texture. If you have questions about applying a fog coat, contact your PPG FBH representative.
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Defined
Shadowing and Streaking
Like banding, shadows and streaks are more obvious when viewed from an angle. Most often, problem areas include stripes down nail rows, marriage lines/close-up issues, and drywall paper that has been “furred” as a result of sanding.
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Common Causes
Shadowing and Streaking
Shadowing and streaking most often occur as a result of over-atomization of the texture. When texture machines run at high psi, excess grit accumulates in the finish. Many plants run texture units “wide open,” with pressure settings at 100 psi.
Sanding of the drywall’s paper field often causes the paper to “fur up.” When texture and paint are applied, these “furred up” areas take on a distinctly different texture from the surrounding surface.
Inconsistent texture materials are sometimes the culprits. Texture materials may vary in quality and age of the material. When two different qualities of material are applied to the same finish, or when old material is applied in the same area as new material, the variation becomes apparent when the material cures.
Inadequate equipment can also contribute to shadowing and streaking problems, when used for repair and during close-up.
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The Best Practice Solution
Shadowing and Streaking
Prior to work each day, establish a grit-free job standard on a separate piece of board. The “hand test” is a good indicator for properly applied texture. The cured texture should not hurt the back of your hand when you swipe your hand across the surface.
- To reduce the potential for grit, mix the texture to a stiff consistency.
- When using a hand-held hopper gun for field application, duplicate the application on a separate board to match the standard applied in the plant. Knowing how to make adjustments so that these two profiles match will minimize problems in the field where they are more expensive to correct.
- Do not over-sand mud-to-field junctures. Though it can be a bit more time-consuming, wet mopping is the preferred method. Reducing the amount of sanding will help to improve the overall finish, and provide a cleaner environment for paint application. Use sanding screens/grids instead of sandpaper. Sanding screens/grids prevent dust from building up on the surface.
- If you must use sandpaper, 120 grit is recommended. 80-100 grit sandpaper is too coarse. An even texture application reduces high/lows in the appearance. A rough texture generally appears darker and shadowed, whereas smooth areas appear lighter and often shinier.
CAUTION: Avoid breathing sanding or grinding dust, as they may be harmful if inhaled.
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Defined
Wet Sanding Alternative
Many professional painters favor the wet sanding method. The term is misleading because it involves no sanding. Instead, a wet sponge or rage is applied to drywall compound to create a smooth surface.
Paint application and finish are greatly improved in dust-free work environments.
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Advantages
Wet Sanding
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No dust is produced, eliminating the need for a dust collector or respirator.
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Little cleanup is required for both floors and walls.
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Wallboard face paper is not scuffed during sanding.
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Joints that are wet-sanded are easier to conceal with paint than joints that are conventionally sanded.
Method
Wet Sanding
Apply an even, thin coat of compound as smoothly as possible to minimize sanding.
The best material to use is a high-density, small-celled polyurethane sponge. This type of sponge resembles high-quality carpet padding. For minor touch-up, a general-purpose sponge or smooth, soft cloth will work.
- Saturate the sponge with clean water that contains no soap or additives. The water temperature should be cool to lukewarm, not hot. Wring out the sponge just enough to eliminate dripping.
- To remove high spots, gently rub the joints in a direction parallel to the joint compound surface. Do not rub down into the joint compound.
- Use as few strokes as possible. Excessive rubbing will groove the joints.
- Clean the sponge frequently.
- Allow wet-sanded areas to dry thoroughly between application of additional material and/or paint.