How to Open the Caulk Tube
The biggest mistake most people make is cutting too much off the tip of the caulk tube. In general, the size of the hole should be about two-thirds the width of the desired caulk joint. Most caulking jobs around the home only require a narrow bead. If you’re caulking woodwork to prepare it for paint, start with the opening very small, just over 1/16-in. diameter. For tub caulking, a 1/8-in. diameter hole is usually about right.
Some caulk tubes need to be punched in order to start the flow of caulk. Nails aren’t always long enough. Use a thin, stiff wire like a scrap electrical wire or coat hanger to avoid enlarging the hole at the tip.
You’ll notice 45-degree marks on the tips of some caulk tubes, indicating the angle you should cut the tube. But some pros recommend a blunter tip angle, about 60 degrees. Give it a try. You can always cut the steeper, 45-degree angle if you don’t like it. Regardless of the angle of the cut, the key is to hold the caulk gun at this same angle while you’re filling the joint.
A smooth tip makes a smooth bead. So use a sharp knife to cut the tip, and follow up by smoothing the tip with fine sandpaper.