Caulk vs silicone: which one?

Use 100% silicone in wet places you won’t paint, and a latex caulk where you will. A hybrid sealant does both, and the name on the tube won’t always tell you which you have.

The name on the tube can mislead

• GE Paintable Silicone Supreme is a silane modified polymer, a hybrid, which is why it takes paint.
• DAP KWIK SEAL ULTRA contains silicone additives, and DAP says it can’t be painted.
• DAP DYNAFLEX 230 has no silicone in it, yet meets ASTM C920 Class 25, the same class as DAP’s window and door silicone.
• DAP ALEX PLUS is a latex with silicone added: 10% or less, DAP’s FAQ says.

Which to pick

GE’s advice is to match the product to the place: moisture-heavy areas call for 100% silicone, and painted finishes call for a hybrid. DAP’s guide draws the line in the same place, with caulk for indoor work where paint and a clean finish matter and sealant for moisture, movement and weather.

• Tub, shower, sink: a kitchen and bath silicone, or a hybrid if you want to paint it. Several DAP latex caulks, such as ALEX PLUS and DYNAFLEX 230, are marked not for a bath or shower.
• Trim and baseboards: a paintable latex caulk, such as DAP ALEX PLUS or GE Painter’s Pro.
• Outside windows and siding: an exterior sealant such as DAP DYNAFLEX ULTRA or Sashco Big Stretch, or a window and door silicone if it won’t be painted.
• Concrete joints: polyurethane such as Sikaflex, or a concrete silicone such as GE Concrete Silicone 2.
• Toilet base: no data sheet we read lists it, and GE’s toilet guide points to a bathroom silicone.

Switching from silicone to caulk

Every bit of the old silicone has to come out first. DAP says ALEX PLUS and DYNAFLEX ULTRA won’t adhere over it, and Red Devil says silicone won’t even adhere to itself. Removing old silicone has GE’s steps.