How to Install Intumescent Sealant

Prepare the surface which you will seal by cleaning it with pure alcohol and rags. Remove any dust, dirt, oil and wax on the surface. If sealing around cables or piping, clean the area on the wall that will receive the sealant, to at least 2 inches outward. Wipe door jams, window seams or floor joints in the same manner, removing all contaminants. If the surface is composed of rough wood, sand the joint seam smooth with some medium 400-grit sandpaper.

Measure the joint or seam width with a ruler. If under 1 inch in thickness, you can apply the sealant without any support backing. Load a calking gun with an intumescent sealant tube. Use wire cutters to snip the end of the nozzle. For a wide bead, cut more of the tip off. Cut a small portion of the tip for a smaller bead or thinner joint.

Hold the tip of the calking gun at a 45-degree angle and depress the gun trigger slowly. Push the bead in front of the nozzle and draw the gun backward. If sealing a pipe joint in a wall, pull the gun around in a 360-degree arc until the end bead overlaps the bead starting point. Do the same for a wire loom surrounded by a grommet -- completely encircle the wire next to the grommet surface, and then underneath the grommet. For a double seal, run a bead around the pipe or wire loom where it exits the wall on the other side.

Cut a strip, or several small strips, of wool fiber with a pair of scissors if the joint or seam exceeds 1 inch in width. Push the wool fiber strips into the joint, far enough to allow 1/4 inch of depth inside the structure. Fill the inside joint with sealant and trowel it smooth with a spatula. Let the inside sealant dry for 15 minutes, then run a uniform bead around the exterior with the calking gun.

Apply a generous bead of Intumescent sealant over a wide seam, crack, hole or depression. Use a spatula to flatten and work the sealant into the depth of the crack or seam, from one end to the other. Smooth the surface with the spatula. For very large or long cracks in walls and floors, do so a section at a time that take no more than 10 minutes to complete, since the sealant will begin to set-up and harden. Use masking tape to tape off any area you wish to keep sealant-free.