Splinters on a wooden 2-by-4 deck handrail can be a real pain in the hand. As moisture penetrates the wood grains and then dries out, the grains separate and splinter. The remedy to the problem of a splintering handrail lies in sealing the wood with a moisture-protective coating such as wood stain or paint. If the handrail has already begun to splinter, you must smooth out the existing splinters before you apply the moisture barrier.
Gathering the Materials You'll Need
Visit the paint section of your local home improvement store. Purchase a 120-grit piece of sandpaper, a 150-grit sponge sanding block, a paintbrush and an exterior stain or paint that matches the existing color of the handrail. If you're not sure about the color, ask for a clear stain or varnish. Grab a bag of painter's rags and a sponge brush if you're staining the handrail. If the handrail has bare wood and you're going to paint it, you'll need to get an exterior wood primer as well.
Prepping the Handrail
Sand the handrail with the 120-grit sanding paper to remove all existing splinters, if applicable. Dust the rail with a dry painter's cloth, then go over the rail with the 150-grit sanding block. This extra sanding will ensure a smoother wood grain texture. Dust the rail again with the dust rag.
Open the can of stain and mix it with a stir stick. Dip the sponge brush into the stain. Apply the stain to the handrail in back-and-forth motions. Apply the stain as quickly as possible to prevent an uneven finish. After every 3 feet of handrail has been stained, rag off excess stain with a clean painter's rag. Allow the stain to dry completely and apply another coat, if a darker color is desired. If you're using a clear stain, you can apply two or more coats. The more coats the better the protection. After the stain has dried for 24 hours, you can apply a varnish coating. This will encase the stain so it won't get on your clothing and better protect the handrail from splintering.
Open a can of primer. Apply the primer to the handrail with a paintbrush. Wait 24 hours for it to dry. Lightly sand the primer with the 150-grit sanding sponge. Dust it with a clean painter's rag. Apply a second coat of primer. Sanding in between the two coats of primer will ensure a smoother finish. Wait 24 hours for the second coat of primer to dry, then apply a coat of finish paint with the paintbrush. Wait 24 hours, then apply a second coat of finish paint. The handrail shouldn't splinter for several years under normal circumstances after you've finished it this way. Stain or paint every few years to ensure it never splinters.