Bamboo is a grass, but when manufacturers press stands together to form flooring boards, the boards can be as tough as maple or oak, and they respond to moisture in a similar manner. They shrink when they dry out, and gaps may form between them. You can generally fill a couple of gaps without much difficulty, but if the issue is extensive, you might need to sand the floor to do a complete job. Even though the National Wood Flooring Association endorses sanding bamboo flooring, the procedure may increase toxic formaldehyde dust in the adhesive used to laminate the grasses.
Inspect the gap before you fill it up. If you can see the tongue of one of these boards, you should have the ability to fill it with latex floor filler. If the gap is wide enough for you to see the subfloor, however, two-part epoxy wood filler is a better choice. Latex filler will sink in the gap and will probably crack.
Choose a latex filler with a color that approximates the ground color. You can touch it up with stain, even if needed, after it dries. Color is more critical when using epoxy filler because you can not alter it with stain. It should be as near the ground color as possible.
Implement latex filler straight from the container with a putty knife. Scrape the knife over the gap to remove as much excess filler as possible and then wipe the area with a damp rag to remove the rest.
Mix epoxy filler together with the hardener which is included with it in the proportion specified on the container. Mix only as much as you are able to use inside the time that it takes for the adhesive to harden. Trowel it in the gap with a putty knife and scrape off the excess.
Wipe the area around a place you repaired with epoxy filler working with a rag dampened with acetone. If you do it before the filler hardens, the acetone will remove the deposits without harming the ground finish.
Spread another application of latex or epoxy filler if the first one settles to form a depression.
Sand the area around the mend with 220-grit sandpaper to remove any deposits that wouldn’t come off with water or acetone. Wipe off the sanding dust, then stain the filler, if needed. Coat latex or epoxy filler with a coat of clear ground finish.