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The following are frequent questions about caulking:

1. How do you get a caulking bead to stay neat and even?
   Use masking tape to tape off the areas around the caulking. Lay down your bead of caulk. Use your finger or foam paint brush to tool the caulk by pushing the excess onto the tape. After tooling, you can remove the masking tape and you'll find a very neat, clean, smooth bead of caulk.

2. What can you use to help keep showers shiny and help mold and mildew from forming in shower areas?
   Next time you clean your bathroom, get out your car polish. Rub a coat of polish on your ceramic or fiberglass shower enclosure. You'll get a wonderful shine and the water will bead-up and roll off before mildew or mold can begin to form. It will make your next cleaning time a lot easier. DO NOT apply car polish the floor of the shower—someone could easily fall on the slippery surface.

3. How do you unplug a used tube of caulk?
   Take the tube and cut a larger opening in the nozzle so that the new hole is slightly larger than the first. Next, drive a screw into the nozzle and use the screw to pull the hardened caulk out of the nozzle. A screw with coarse threads, such as drywall or deck screws, works best.

4. What's the best way to seal up used caulk?
   You just finished your caulking job and there's product still left over in the tube. A plastic electrical connector is an easy way to quickly seal and reopen the tube. If you can't find a connector, place a 2" nail into the end of the nozzle, then wrap the entire nozzle tightly in plastic wrap. This will keep the caulk in the nozzle from hardening for use at a later date. Of course, if the tube comes with a cap, use the cap instead.

5. Is there a way to repair chipped ceramic tile?
   Yes. Simply apply some appliance touchup paint. This paint dries to a very hard finish and sticks well to smooth surfaces. Appliance paint comes in only a few colors (white, almond, green, yellow and back) but it can be tinted with other paint to match your tile.

6. Will sun-damaged wood fibers cause adhesion problems with my caulk?
   Surface wood fibers can get damaged in as little as 2-4 weeks when exposed to direct, intense sunlight. Anything applied to this damaged wood (including stains, paints, caulk, etc.) will easily fall off over time because they're aren't sticking to a good, clean, sound surface. So, be sure sun-damage wood is removed from the surface before applying anything over top.

7. Can oil-based caulking compounds cause windows to "fog up?"
   Yes. Never use an oil-based caulking compound around insulating glass ("thermal-pane") windows. The vegetable oils in these types of caulks attack polysulfide polymers (the primary sealants used in these windows). As the polysulfide degrades, it cracks and causes the window to "fog up."

8. What does it mean when a caulking bead shrinks?
   Not a whole lot. Shrinking of a caulking bead is normal. While it doesn't usually affect performance, some people like a flat bead so multiple applications are sometimes necessary in order to create that nice, flat surface.

9. How long does it take for elastomeric latex caulks and water-cleanup caulks to cure?
   It depends on the product. The majority of the curing takes place in the first 1-3 days after application, but full cure can take anywhere from 2-4 weeks, depending on temperature and humidity. Always follow the manufacturer's instructions on wait time when painting over a bead of caulk.

10. What is the difference between cohesive and adhesive failure and why is this important?
    When cohesive failure occurs, the bead cracks or tears down the center.

    Possible causes & solutions to cohesive failure:

    1. 3-point adhesion: the caulk bead is sticking to the back of joint, as well as the sides, and the caulk can't stretch correctly.

       Solution: Before you caulk, insert a backer rod into any joint larger than 1/4" and 1/4" deep. If the caulk has already split, simply apply more caulk over the existing bead. (Note: you can't do this with silicone, as it won't stick to itself. So, stay away from silicone or remove all the silicone and re-caulk.)

    2. Oils in a paint or stain causes the bead to "dry" and "crack": this means that the caulk and other product are chemically incompatibility.

       Solution: You will need to remove one of the products and use a different one that is known to be chemically compatible.

    When adhesive failure occurs, the caulk bead does not adhere to one or both of the substrates to which it is applied. This is a more difficult problem to solve.

    Possible causes & solution:
    1. Product incompatibility with a paint, stain or previous caulking (usually silicone) which has already been applied
    2. Incompatibility with the substrate itself (some rubbers, polypropylenes, polyethylene's, neoprene, some oily woods, slick or waxy surfaces, etc).;
    3. Application error (not enough product applied to withstand joint movement, poor tooling, etc.)

    Solution: The caulking bead needs to be removed, the surfaces cleaned and primed properly, and the caulk can then be reapplied.

11. What is the difference between open cell & closed cell backer rod and where is each most effective?

    Open cell is softer and more "spongy"

    • Advantages: it will fit into tight places and "cling" to the joint better.
    • Disadvantages: if water does leak behind the caulking, the backer-rod will soak up the moisture like a sponge rather than help to seal the joint off.

    Closed cell is firmer and not nearly as porous.

    • Advantages: it helps seal the joint off better if water leaks behind through the caulk. It remains firm even in contact with moisture.
    • Disadvantages: it is harder to "stuff" into tight or uneven spots and harder to get it to "cling" and conform to the space it is in.

    In general, closed cell is the way to go in exterior applications. It is always best to have whatever is behind the caulk repelling moisture. On the interior, personal preference should be your guide.

12. I have blisters in the caulk I applied. What caused them, and how can I fix them?
    First, the good news: blisters are easy to fix.

    Fixing blisters in dried/cured caulk: Cut out the blister, fill in the cavity with new caulk, and tool it so it's smooth and matches the existing caulk bead. A couple of applications may be necessary to get a uniform look.

    Fixing blisters in fresh/not completely cured caulk: Simply pop a hole in the blister to release the air, push it in to seal up the cavity, then apply a bit more caulk over top of the blister. Tool the caulk so it's smooth with the rest of the caulk line. Done!

    Most blisters in caulking happen when large amounts of moisture vapor try to evaporate out of the caulk line too quickly and after it has skinned over. This is more likely to happen when the caulk is applied in direct sunlight, to hot surfaces, in hot temperatures, or to wet surfaces. We know that those conditions are not always avoidable, so some blistering is normal and to be expected. When possible, apply caulking during the cool part of day, out of direct sun and to dry surfaces. If you can't, remember that repairs are easy.