We have all seen it, done it and had it happen to us. Masking tape on a painted gypsum wallboard surface can pull the paint off the surface. When this happens on new construction or a remodel, you hear all sorts of comments.
“I have been doing this for 30 years, and this is the first time I have ever seen this.”
“This did not happen on the last project.”
“It’s not my issue-it’s the painter’s or the taper’s fault.”
These phrases are heard more and more today. This article will try to discover the root of the problem and stay away from mere finger pointing or finding someone to blame. Let’s evaluate the issues and try to understand where, when and what causes this sticky issue.
Adhesive tape, or commonly known as masking tape, is generally used over gypsum wallboard surfaces to mask and protect surfaces, to create temporary barricades, to help make straight lines for painting, mounting temporary signs and so on. Unfortunately, when removing adhesive tape, occasionally portions of the paint coating assembly (top coats of paint and primer) along with some of the finishing joint compound-or in severe cases-gypsum wallboard face paper, may be pulled from the surface by fracturing one of these components; creating what is looked upon as a failure in the paint or the joint compound.
Final Decoration of Gypsum WallboardJoint compounds are formulated with different adhesive and cohesive strengths; this is determined by the amount of binder (glue) in the formula. All-purpose compound (used in the beginning steps to fill depressions and embed the tape) will typically have more binder in it than a finishing compound (used in the final steps to feather and smooth). When evaluating a complete interior wall finish assembly (gypsum wallboard, joint compounds, primers and paint coatings), it should be understood that the finishing compounds typically have the lowest cohesive strength of the entire assembly, but with sufficient adhesive strength to bond to the previous coat of joint compound and/or gypsum wallboard face paper. If adhesive tape is used and it pulls the paint from a finished surface, this should only demonstrate that the adhesive strength between the adhesive tape and the paint is greater than the cohesive strength of the compound itself, or the fractured component, and this should not automatically be considered a failure.
Completed gypsum wallboard surfaces (prior to paint finishes) can have variations in absorption. The areas of thicker compound (over joints, fastener and feathering of joint compound over attachment flanges of accessories) can have a higher absorption rate than an area of thinner compound or even raw gypsum wallboard face paper. To help minimize this absorption issue, ASTM C 840 requires that Levels 3, 4 and 5 shall be covered with a “drywall primer” that is compatible with the final decoration.
Drywall primer is defined as a paint material that is applied as the first complete coat in a painting assembly (applied by the painting contractor) and is formulated to be applied directly over new (untreated) gypsum wallboard, joint compound and even skim coats (Level 5).
On the opposite end of the scale, there are drywall primers that are formulated (high in volume solids) to be applied at heavier dry film thickness. These primers can also provide good angular sheen hold-out, as well as providing uniform absorption, assisting with adhesion, and minimizing the incidence of removal of the paint and joint compound due to tape and impact stress. The performance level is quite high with little to no fractures of the paint from the substrate when these types of drywall primers are used.
Moisture (from the primer) that enters and becomes trapped within the assembly can re-wet and compromises the cohesive strength of the joint compound, and in some cases even swell the wallboard and materials. To help protect this low cohesive strength of the joint compound, primers and paints shall be applied in accordance with the manufacturer’s recommendations and the correct primer should be used. It should also be noted: job site conditions that are not within standards may also delay drying times, which may result in weakening the assembly.
Primers are applied by volume and not by weight, so ideally the drywall primer should be enriched in volume solids. Volume solids are the amount of solids in a given volume that remains on the substrate after all of the liquid components (volatiles) have evaporated from the surface, providing film build. A higher film build will help fill, mask minor surface imperfections and protect the low cohesive strength of the joint compounds from excessive moisture. So drywall primers not only affect the final appearance, but they also have different performance levels. The type of drywall primer used shall be determined by the performance level that is desired by the designer/architect and shall be specified in the painter’s scope of work.
Adhesive Tape Applied to Finished Gypsum WallboardThe type and sheen of paint may affect the bond of the adhesive tape to the finish paint coating. Typically, flat sheen paints (low latex solids) provide a flat, chalky-looking surface. The reason flat sheen paints have a lower sheen is because of the rougher grind of the pigments (solids). When dried, these rougher ground particles project through the surface, providing a diffused reflection which accounts for the lack of gloss or sheen. Adhesive tape may attach onto these projecting particles easier which in return strengthens the hold/grip between the adhesive tape and the paint finish. Higher gloss paints (high latex solids) have finer ground pigments (solids) and will provide a slicker, smoother and/or shiny surface. Adhesive tapes may not attach as well to slick surfaces (lack of projecting particles); meaning the hold/grip strength between the adhesive tape and the paint finish may not be as strong as in flat finish paint.
Also keep in mind, volatile organic compounds can have an impact on adhesion. Paints that are formulated with lower VOCs are inherently “softer” and may provide more “tack” (adhesion) than a paint that is formulated with higher VOCs. Meaning, a semi-gloss paint with low VOCs can produce a very smooth finish, but with the softer formula, the hold/grip strength between the adhesive tape and the paint finish may be increased. All primers and paints are recommended to be applied at their designed wet film (mil) thickness by either a roller or a sprayed and back-rolled application, keeping a wet edge.
For delicate surfaces, such as freshly painted walls, an adhesive tape with the lowest adhesion level is recommended. Adhesive tape should be applied to clean, cured surfaces with standard hand pressure, not burnishing the adhesive tape. It is advised to first try a location to see how the tape may act with the gypsum wallboard (i.e., will it fracture the paint and joint compound from the surface, damaging the finishes).
It is also recommended not to leave adhesive tapes applied to surfaces longer than manufacturers’ recommendation; adhesion increases the longer it is applied to the surface. Exposure to direct sunlight can shorten these periods as well and so quicker removal in these instances may be required to avoid damage.
Adhesive Tape RemovalMajor adhesive tape manufacturers recommend adhesive tape should be removed at a 45 degree angle from the decorative surface and roughly at a speed of 1 inch per second. If the adhesive tape starts to remove the paint from the surface, scoring the edge of the tape with a razor blade before pulling is recommended.
At the present time, there is no industry standard or recognized test for measuring adhesion with the use of adhesive tape over final decorated gypsum wallboard. ASTM D 3359, “Standard Test Methods for Measuring Adhesion by Tape Test,” are methods covering procedures for assessing the adhesion of coating films to metallic substrates, and is often misused as a tape test for gypsum wallboard with final decoration.
Due to the unlimited number of primers, sealers, paints, methods of applications, job site conditions, adhesive tapes, etc., it is recommended that a mock-up be constructed, evaluated and accepted by responsible parties for cosmetic acceptance and durability before any production decorating is started. The mock-up should remain intact until the project is completed.
Things to Keep in MindPaint sealers (low volume solids) are typically formulated to act as a barrier (resistant to penetration). When directly applied over untreated joint compound, the moisture may travel into the joint compound instead of exiting the assembly. This moisture can rewet the compound; weakening the cohesive strength of the compound. Sealers are not recommended directly applied over untreated joint compound.
The surface shall be wiped and free of foreign materials and dust before applying any paint materials.
Some manufacturers recommend diluting their primers, sealers and/or paints a small percentage to allow the products to flow better. However, diluting or over-thinning these products to get more “mileage” can cause problems with adhesion in the substrate coatings and will also reduce the film build. When these over-thinned products are applied over joint compound, the moisture can also rewet the compound; weakening the cohesive strength of the compound.
Joint compounds and paints need to fully dry or cure to develop their strength. Application of subsequent coats over prior non-dried coats may hold moisture in longer and can lead to weakening cohesive strength and bond strength of the compound.
All primers and paints are recommended to be applied at their designed wet film thickness by rolling, spraying, or sprayed and back-rolled, keeping a wet edge. If not, this will yield the paint’s designed dry film thickness.
Correct adhesive tape removal techniques shall be followed.
Job site conditions, scheduling and drying times for joint compound are not followed per industry recommendation.
ClosingThere are a number of reasons why this “tape adhesion” or “sticky tape” issue occurs and it is typically not the result of just a single component failing that causes the issue. Understandably, this is a lot of information to digest at one time, however, before blaming a contractor or a product over this perceived “failure,” review all the application steps, literature for all of the products used, and consult with all of the parties in one meeting. With current product formulas changing, new products being introduced and alternate methods of application being done, one should listen to the applicators, consult with professionals and, please construct a mock up panel. Otherwise, you may be the one getting “stuck.”
* A cut down version of this information can be found on a one (1) page Technical Bulletin sheet, located at www.tsib.org/pdf/technical/30-400_gypsum_wallboard_and_adhesive_tape.pdf.