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FAQ: Caulks & Sealants

Paint cracking around caulk joints

The paint most prone to cracking over newly applied caulk is a cheap interior flat Latex. If you use this paint, there is no room for error, and the caulk must be allowed to fully dry (overnight) before painting. Premium paints do not have this same problem, and seem to have less cracking issues over newly applied dry caulk.

Why don't caulks "stick" sometimes?

Caulks don't stick to dust, chalk, dirt and other contaminants. Also remove any loose or damaged substrates. Washing an area and letting it dry before caulking can really improve adhesion.

At what temperatures should caulks be applied?

The best application temperature range for caulks is 60°F to 85°F.

Should I prime before applying sealant?

Priming is generally not necessary before sealing if surface is sound.

What does "elastomeric" mean?

The term elastomeric refers to the ability of a material to stretch and then return to its original shape, i.e., it has "memory." Elastomeric caulks are normally the better choice and an excellent choice with any kind of paint.

How wide/thick should I apply caulk?

A line of caulk (called a "bead") should be no thinner than ¼." Thinner beads shrink while drying, creating too thin a seal to tool or seal properly.

When should you use a Backer Rod?

When filling a crack, seam or joint that has a gap wider and deeper than ¼", a foam backer rod is first placed in the gap to partially fill it. Backer rods improve adhesion and flexibility of the seal by creating an hourglass-shaped seal with the caulk.

Which caulk is best for caulking around sinks and tubs?

Tub & Tile Caulk is recommended in areas where there is high humidity and intermittent water contact such as kitchens and bathrooms. Tub & Tile Caulk contains added mildewcide to give consumers extra mold & mildew fighting protection.

What is mildewcide?

Mildewcide is an additive in caulks and paints that deters the growth of fungus, mold and mildew on the dried caulk film.

How can I ensure that mildew will not grow on my caulk?

Mildew can grow anywhere there is darkness, dampness and a food source. Clean the area you are going to caulk with a bleach and water solution. 

Bead Size: How thick do I apply it?

The best rule of thumb is to use your finger to wipe down a caulk bead. Do NOT use a rag as it will wipe away too much caulk and lead to cracking. You don't need to use more caulk, just don't wipe away the product you have already used! Remember to moisten your finger before tooling the caulk. The moisture allows for a smoother finish.

Help with Drying Time

Our specially formulated caulks offer standard, faster, and slower dry time options. We have a caulk that meets your job needs ranging from the cool Northeast, to the humid Southeast, to the dry Southwest, and the moist Northwest. We provide solutions to keep you painting through all climates and conditions.

Know when to stop!

If it looks good, walk away! Trying to create the perfect bead is a good way to mess up an otherwise acceptable job.

Preventing after flow

Remember to immediately release the trigger on the caulking gun each time you complete a bead. This helps to reduce the amount of caulk that weeps from the tip.

Sealing Crown Molding

Decorative molding demands the best caulks that have great adhesion and flexibility. Crown molding expands and contracts due to the temperature differences in rooms. Temperatures can differ up to 15 degrees from floor to ceiling, and crown molding must endure the greatest temperature movement. Use only high quality elastomeric caulks for this application.

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The information on this site is provided as a free service. It is based on common conditions and may not apply to your specific situation. Please contact a Black Jack representative with specific questions or comments. 

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