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Common Paint Problems:

Caulk

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Troubleshooting Common Caulk Issues

The following are some common and less-common issues seen in caulking and, most importantly, some techniques to avoid them:

Caulk Bead Cracking

Customers may experience problems with caulk separating from wood trim such as crown molding and kitchen cabinets. In some cases, it is not the caulk failing; it is actually a problem with the new wood’s shrinkage and movement due to the varying atmospheric conditions and excessive moisture content. The movement and/or change in joint size is a result of moisture reduction and shrinking of the wood fibers and, most commonly, it results in hairline cracks in caulk beads and painted joints, as well as separation in the panels of doors. When caulk is applied to unprimed new wood, that wood will wick moisture from the caulk while the caulk is trying to cure. The moisture imbalance will prevent the caulk from coalescing properly, resulting in a cracked or separated caulk bead. Priming the new wood substrate prior to caulking can help to prevent this issue.

  

Paint Film Cracking

Caulk users have also reported paint film cracking overtop of acrylic caulk beads. Again, most often the problem is not with the caulk.

Today’s paint manufacturers offer many products with enhanced attributes: easy to touch up, washable, mar resistant, and very fast drying. The high-gloss paints, sealers and primers dry to a hard film that is rigid, and not designed to flex or stretch. Caulk, depending on the thickness, can take 72 hours or more to fully cure and evaporate the water from its system. As the curing occurs, the caulk naturally shrinks. When the coatings dry faster than the caulk can cure, it puts a lot of stress on the primer or paint film and causes film cracking at the interface of the caulk bead and paint. Allowing the caulk to fully cure before coating is one part of the solution.

The other part of the solution is using a high-performance painter’s caulk. Caulk manufacturers have been able to formulate unique properties into specialty products designed to help reduce cracking of rigid coating systems.

And finally, avoid using entry-level caulks. Though they will save you money, they simply don’t have movement capability. To span wide gaps or move with dynamic joints, choose a caulk with elastomeric attributes or elongation properties.

  

Plasticizer Bleed

Discoloration or paint ‘shiners’ has been noted in certain combinations of paint and caulk. Caulk manufacturers often use plasticizers in their formulations, an additive used to increase flexibility. If the manufacturer chooses a plasticizer that is compatible with the acrylic polymer, it won’t leach out of the caulk. However, if the plasticizer is not compatible, it can migrate or ‘bleed’ out of the caulk and potentially result in discoloration, stiffening, excessive shrinkage or brittleness.

Additionally, plasticizer migration to the caulk’s surface or through the paint film can promote dirt pickup or mold and mildew growth by merely increasing surface tack such that airborne nutrients stick to the surface.

  

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Content and images in this blog are courtesy of Ray Heck, VP of Marketing for Tower Sealants. 

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