Adhesives and Sealants — FAQ
Can I paint over silicone caulk?
No. 100% silicone repels paint. Use acrylic latex or hybrid sealant for paintable surfaces. If you must paint silicone, apply a specialty bonding primer first, but adhesion remains questionable. For trim work, choose paintable from the start.
What's the difference between acrylic and silicone?
Acrylic latex is water-based, paintable, and easy to clean up, but less durable in wet areas. Silicone is rubber-based, permanently waterproof, and flexible, but cannot be painted and requires solvent cleanup. Hybrids offer both benefits at a higher price.
How do I smooth caulk without making a mess?
Tool acrylic latex with a wet finger or damp sponge within 5 minutes of application. For silicone, use a caulk-smoothing tool or finger dipped in soapy water. Keep a consistent 45-degree angle and light pressure for a concave joint. Never tool after skin forms.
Why is my new caulk cracking?
Cracking indicates excessive joint movement or wrong caulk type. Rigid acrylic on wood trim fails when boards expand. Use elastomeric urethane formulas for moving joints. Ensure the gap is less than 1/2-inch wide and use backer rod for deep joints.
Can I apply caulk over old caulk?
Never. New caulk won't bond to old, failing material. Remove all old caulk completely with a utility knife and caulk remover solvent. Clean the joint with alcohol, let dry fully, then apply new caulk to bare surfaces for proper adhesion.
How long does unopened caulk last?
Silicone tubes last 2-3 years unopened. Acrylic latex lasts 12-18 months before separating. Store tubes upright in cool, dry conditions. Check the manufacture date on the tube—older stock may be partially cured in the nozzle, causing application problems.
