- the size of the joint at the time of caulking
- the contaminants on the surfaces of the joint (like dust, pollen, etc.)
- the ability of the caulk to “wet” the surfaces of the joint for good adhesion
- the ability of the caulk to properly cure and develop its ideal physical properties
Ideal Weather Conditions
Plan to caulk in ideal temperatures whenever possible. What is ideal? 50°F and rising and 90°F and falling. Be sure to pay attention to the surface temperature where you’ll be applying the caulk. It should also fall within that idea temperature range.
Wet / Snowy Conditions
If it has just rained or snowed, allow the surfaces to completely dry before caulking. Wet surfaces will make proper adhesion difficult and may inhibit proper curing of the caulk. In the same way, avoid applying caulk – even in ideal weather – if rain or snow is expected within 24 hours. If you need to get the caulking done, go ahead and do it. Just make sure to cover your work with a plastic tarp to prevent moisture from getting onto the caulk and causing it to wash out.
It is never good practice to apply caulk in extreme temperatures. Whether hot or cold, the joint will not be at its ideal size, the caulk will not cure correctly (which causes performance problems), or the caulk may develop blisters. Any weather-related problems with the caulk can be fixed fairly easily, but are also avoided altogether through simple weather watching.
Warm Dry Surfaces
Make sure the substrate is clean and dry. In cold weather a thin layer of ice can form on the substrate and if you apply caulk on top it, the water between the caulk and the substrate will prevent the caulk from adhering. You can use a hair dryer to melt the ice and warm the substrate or, even better, clean the substrate using either methyl ethyl ketone or acetone (available at home stores). This will not only get rid of the ice, but ensure the surface of the substrate is clean, so the caulk can bond tightly.
Warm the Caulking Tube
Keep your tubes of caulking warm until just before you want to use them. Even high performance cold weather caulk won’t flow smoothly or easily when it’s cold, so it won’t get right down into the joint. Of course, we think you can find the perfect warming bags for all your adhesive and sealants on the job-site here: caulkwarmer.com
Just another expert idea from Guy Calor, the Caulk King and CaulkWarmer