9 practical tips for using sealants

When you need to seal a joint or crack, you'll reach for a sealant. Here are nine practical tips on how and when to use it.

  1. The best time to seal a joint outdoors is during the spring or autumn. During these seasons is when the width of the joint is halfway between its winter and summer extremes.
  2. Avoid the most common caulking mistake: cutting the nozzle too far back from the tip. Doing so makes the hole in the nozzle too big and allows too much caulk to gush out. What professionals do is match the nozzle hole size to the size of the gap they're filling. But a nozzle hole that's smaller than the gap gives you more control. Such a small nozzle hole allows you to move quickly where the gap is narrow and to slow down to get more caulk into larger gaps.
  3. Cut the nozzle very near the tip at a 45 degree angle. For most jobs, you'll want a nozzle hole that's no more than 3 millimetres (1/8 inch) across. If your first hole ends up being too small, remember that you can always make a second or third slice to enlarge the hole — you just can't make it smaller.
  4. For a smooth bead of sealant, start at one end of the crack and finish at the other. Don't make any stops in between — not even at corners — if you can help it. Stopping and starting while applying sealant will leave you with a bumpy bead.
  5. For a pleasing, even finish, make sure the caulk flows out of the nozzle at an even rate, so pull your gun's trigger slowly and steadily. When the trigger reaches the end of its stroke, release it quickly and begin pulling again instantly. The pressure in the tube will keep the flow going during the split-second interruption.
  6. Use a plastic drinking straw as a handy extension tube for sealing hard-to-reach places. Secure your extender on the end of your caulking tube with cloth tape. Leave it on when you've finished and tape up the end. Remove the tape when you're ready to use your extender again and you'll have a fresh start.
  7. Whether to pull or push a caulking gun while filling a crack is something that even experts disagree about. Both methods work well, since what really matters is that you force the sealant well into the crack. If you prefer pulling, cut the sealant tube spout at a 45 degree angle, then hold the gun at a 60 degree angle as you pull it along the crack. Or, if you prefer to push, cut a double angle on the spout (so that the resulting point looks like an equilateral triangle) and hold the gun at a 45 degree angle as you push it along the crack.
  8. Don't smooth sealant with your finger. Some sealants contain harmful chemicals, and some are hard to remove from your skin. Instead, use an inexpensive plastic smoothing tool, or a plastic spoon, a craft stick, a piece of potato cut to shape, or even an ice block for solvent-based sealants. Along with being safer, any of these will do a tidier job than a finger.
  9. Instead of shoving a screw into the nozzle after you've used a small quantity from a new tube of sealant only to find the caulk dried out when you need it months later, try pushing a blob of kneaded poster putty over the nozzle. The putty will keep your sealant fresher for longer.

If you keep these nine practical tips in mind on your next sealing job, you'll likely end up with a nicer beads and be able to keep your sealant fresher longer.

9 practical tips for using sealants
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