How do I use a caulking gun and what tip size is best for sealing gaps between trim and walls before painting in my NB home?

Using a caulking gun properly is essential for achieving professional-looking trim work before painting. For gaps between trim and walls in most NB homes, a 1/8-inch (3mm) bead is ideal — large enough to fill typical gaps but small enough to tool smoothly without excess squeeze-out.

Loading and preparing your caulking gun starts with cutting the cartridge tip at a 45-degree angle. For interior trim work, cut the tip to create a 1/8-inch opening — you can always cut it larger if needed, but you can't make it smaller. Pierce the inner seal with a long nail or the wire cutter built into most caulking guns. Load the cartridge into the gun with the plunger rod pulled back, then advance the rod until it contacts the cartridge base. Test on scrap material first to get a feel for the pressure needed.

The key to smooth caulking is consistent pressure and steady movement. Hold the gun at a 45-degree angle to the joint, squeeze the trigger steadily while moving along the gap at a consistent speed — about one foot every 3-4 seconds. Keep the tip in contact with both surfaces (trim and wall) as you move. In older NB homes with settling and seasonal movement, gaps can vary in width, so adjust your speed accordingly — slower for wider gaps, faster for narrow ones. Release trigger pressure and pull the rod back slightly at the end of each run to stop the flow immediately.

Tooling the caulk bead immediately after application creates the smooth, professional finish that makes trim look built-in rather than added on. Use your finger, a caulk tool, or even a plastic spoon dipped in water to smooth the bead within 2-3 minutes of application. Work in 3-4 foot sections rather than trying to caulk entire walls at once. In NB's variable humidity, latex caulk can start skinning over quickly in winter's dry indoor air, so don't get ahead of yourself.

For NB homes specifically, use a high-quality paintable acrylic latex caulk that remains flexible through our freeze-thaw cycles. Many older homes in Moncton, Fredericton, and Saint John have significant seasonal movement, and rigid caulks crack within a year. DAP Alex Plus or Tremco Dymonic 100 are popular choices among NB painters. Avoid using caulk in gaps wider than 1/4 inch — these need backer rod or wood filler first. Also, don't caulk the bottom edge of baseboards to the floor — this joint needs to move and breathe.

When to hire a professional: While caulking seems simple, achieving consistently smooth, straight lines takes practice. If you're painting an entire home's trim or have complex crown molding, consider having a professional painter handle both the caulking and painting — the time savings and superior finish quality often justify the cost, especially in formal living areas where imperfections are highly visible.

Find local painting contractors through the New Brunswick Construction Network directory if you'd prefer professional results on your trim work.