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Caulk: How to Caulk

Basic tips to apply caulk


USA, Texas, Dallas, Man with Caulk Gun working in bathroom
Matt Taylor/Getty Images

Caulk: How to Caulk

Knowing how to caulk is an essential task that every builder must understand. However, caulking has many limitations that need to be understood to produce a nice looking aesthetic surface. Caulk material is essential to provide a transition between two or more construction materials adjacent one to another. Caulk is applied in areas where the joint is not perfectly sealed and to reduce air or water transition. Caulk is recommended to fill cracks or joints up to ½ inch wide. Caulk can also be used on wider joints but must be accompanied by other elastomeric products to fill in the joint.

Caulk Types

Caulk are usually divided into paintable or non-paintable caulk. Caulk regularly used around the home and around windows and door joints is paintable caulk. Paintable caulk can receive paint coating after it has been dried. Non-paintable caulk is usually composed of silicone, a material the does not allowed paint to adhere to its surface. It is not recommended on walls, moldings, or around windows. Caulk products today when properly applied could last over 20 years if maintained properly.

Caulk Benefits

Caulk products offer many benefits such as:

  • Do not harden excessively.

  • Do not crack over the years.

  • Caulk allows material to expand and contract regularly.

  • Caulk does not prevent movement.

  • Caulk will produce a water or air tight environment reducing heat loss transfer in some situations.

Tips When Applying Caulk

  • Use caulk for joints or cracks up to ½ inch wide.

  • Do not apply caulk over dust.

  • Apply a primer coat before caulking.

  • Caulk adhered best to painted surfaces.

  • When applying caulk over wood surfaces make sure to paint the wood surface first.

  • Do not cut the tip of the caulk tube to produce a large hole, it will reduce the amount of caulk flowing out of the tube.

  • If the joint or crack is less than ¼ inch, try to widen it using a putty knife.

  • Applying caulk with a gun should be done slowly while moving the gun at the same rate.

  • Clean the spout and your hands using a damp cloth, this should keep you mess-free. A wet caulk-smoothing tool can also be used within two to five minutes of application.

  • Caulk applied around moldings should be sufficient enough to fill the crack only. Use enough pressure with the tip of your fingers to shape it into clean corner joint. Round joints are harder to paint.

  • Tubs, lavatories, sinks, bidets and shower should be clean and dry before caulking. Do not apply caulk over mold, wet, or if mildew is present in previous caulk. If caulk is applied over wet surfaces, it will not adhere properly.

  • Swab the joint with rubbing alcohol to remove soap scum, body oils, and other residue. Rubbing alcohol dries quickly and leaves the surfaces impeccably clean so the new caulking will adhere well.

  • It is recommended to caulk the bathtub when it is filled with water. The water weight will produce strains over the surface creating the largest possible joints between the wall and the bathtub.

  • Caulk can be painted without primer.

  • When a near finish is required, low-tack tape should be used over sensitive or already finished surfaces. Allow the caulk to dry before removing the tape. Do not apply caulking in excess.

  • Caulking can and will shrink as it dries. Sometimes a second layer of caulk is required and will produce a neater surface instead of overfilling a crack with caulk.

  • If caulking is to be applied over existing and previous sealed joints, removing old caulk is essential and need to be done carefully. A wire brush is recommended is the caulk will be removed from concrete and masonry surfaces.

  • To clean the area around the caulk, use mineral spirits for silicone caulk, and soap and water for acrylic.

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