tips for applying caulks

Caulking can be tricky for an inexperienced homeowner. You should read carefully the instructions on the caulking cartridge, and pay close attention to preparation. Preparation is often as important as installing the caulk or choosing it.

Preparation

Removing old caulk or paint residues is obviously important, but often insufficient, namely in exterior joints. Scrapping, brushing, dusting, application of a primer, the use of a backer rod in critical joints or choosing the right temperature and weather to apply the caulk is also very important.

Cleaning

Porous materials like masonry or wood may need scrapping, and also brushing and dusting, while non-porous materials like most metals require cleaning with an adequate solvent. Cleaning dirt and grease with water is often sufficient, while oil may demand a proper solvent...

Primer application

The application of a primer on both sides of the penetration may also be necessary. It depends on the caulk (pay attention to the specifications of the product) and on the materials surrounding the gap.

Critical joints

On critical joints, caulking should be flexible and strong. And to achieve it, caulking should not adhere in three places, only in two. To get it, you may use a backer rod between the joints (the caulk will not stick to the backer rod, allowing flexibility; and the roundness shape of the rod will create a thinner bead and extra-flexibility).

Dry surfaces

Make sure the area to be caulked is dry. Apply the caulk in low humidity conditions. Otherwise you will risk moisture and cracks (from swelling with moisture).

Warm temperatures are also advantageous or necessary to a good adherence and a proper setting. The best time to apply caulk is when the temperature is above 45°F/8°C.

Caulking Guns

If caulking with a gun, keep it at a consistent angle. The right angle is the one that forces the caulk into the crack as it comes out (45º is the best for getting deep).

Do not apply too much caulking: release the trigger before pulling the gun away, or use a caulking gun with an automatic release.

Continuous stream

Caulk in one straight continuous stream, whenever possible. It’s important to avoid stops and starts. To avoid bubbles, the caulk should be sent and fill the bottom of the opening.

Make sure the caulk sticks to both sides of a crack or seam, without oozing out of it. If the caulk shrinks, reapply caulk; caulking should form a smooth bead, sealing the entire crack.