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Q. Why do some caulks crack after they have been applied?
A. When joints are filled with too much caulk (in excess of ½" width or depth) the product tends to shrink as it dries, resulting in cracks. A foam backer rod must be used for joints deeper than ½" inch. When joints are filled with too little caulk (less than 1/8" in width or depth), the product tends to have little ability to accommodate for joint movement, which makes it prone to cracking. When properly applied, caulk should bridge the joint with attachment to 2 sides of the joint.
Q. Why do paint films crack when applied to caulking?
A. There can be more than one reason for the appearance of cracking. In many instances, it is not the caulk that has cracked, rather the paint film on top of the caulking that has cracked. In an assembly where a brittle coating (flat latex paint) is applied over a more flexible substrate (caulking product), exposure to significant joint movement may result in the appearance of cracking in the less flexible surface coating. To avoid cracking in the paint's surface, allow for complete recommended dry time on the caulk's packaging and then paint.
Q. Clear acrylic latex caulks are white when first applied. How long does it take to turn clear?
A. Clear acrylic and latex caulk such as DAP® DYNAFLEX 230®, DAP® ALEX Plus®, DAP® Kwik Seal® and DAP® Kwik Seal Plus® apply white, and turn clear in 7 to 14 days (depending on joint depth, temperature and humidity). DAP® Silicone Plus™, DAP® SIDEWinder®, DAP® 3.0™ All Purpose Advanced Sealant, and DAP® Clear Flexible Sealant apply and dry clear.
Q. What is the recommended dry time for most acrylic and latex caulks before you can apply paint?
A. Most acrylic latex caulks can be painted approximately 2 to 4 hours after application. Cool or humid conditions, large joint depths and type of paint used may require a longer wait time. Clear acrylic latex caulks must be allowed to cure for 7 to 14 days or turn completely clear before painting.
Q. Which DAP caulks or sealants are the most flexible?
A. The ASTM C 920 tested products are the most flexible. Our family of flexible, high performance caulks and sealants include DAP® 3.0™ All Purpose Advanced Sealant, DAP® DYNAFLEX 230®, DAP® SIDEWinder®, DAP® Silicone Sealant, DAP® Silicone Plus™ Premium Silicone Rubber Sealant, , and DAP® Premium Polyurethane.
Q. I used a non-paintable silicone sealant and now I need to paint the surface. What should I do?
A. The non-paintable sealant must be completely removed and replaced with a paintable sealant. Note: Paintable latex caulks may not adhere to silicone products or their residue.
Q. Are caulks stainable?
A. No. In order for most stains to perform properly, they must be able to penetrate the surface that they are applied to. Most caulk will allow paint to bond as paint lays on the surface in a film. Caulk will not absorb stain because the surface of the caulk will prevent the stain from penetrating.
Q: How do I remove silicone?
A: Uncured non-latex based caulk can be wiped away with a solvent such as mineral spirits, acetone, or lacquer thinner. However, once it has cured, there are no solvents or other chemicals that will work to remove it or soften it. Cured silicone must be physically cut or scraped away; a razor type blade would work the best, as it is a precise cutting tool.