Before you attempt to refinish eucalyptus, learn why this type of wood is poorly suited for stain absorption. Unlike softwoods, such as pine and cedar, eucalyptus has a dense wood grain that causes stain to absorb unevenly. If you use a dark liquid oil-based stain on eucalyptus, expect to generate blotchy results. Sidestep this potential occurrence by finishing the eucalyptus with a special gel-based stain, engineered to promote even absorption. Choose a light colour of gel stain and apply it in the correct manner, or you may end up with disappointing results.
Sand the wood with 180-grit sandpaper. Sand along the eucalyptus wood grain until the existing finish looks dull.
Wipe sawdust from the eucalyptus wood using tack cloths.
Cover all areas next to the eucalyptus wood with painter's tape. Place dust sheets beneath the eucalyptus.
Use a 2- to 4-inch natural-bristled paintbrush to coat the eucalyptus with a light coloured gel stain. Brush along the eucalyptus wood grain. Wait four to six minutes, and then wipe the gel from the wood, using cloth rags. Wait four hours for the eucalyptus to dry.
Use white spirit to wash gel stain from the natural-bristled brush.
Use the clean brush to coat the eucalyptus with varnish. Brush along the eucalyptus wood grain, applying only a fine, light coat to prevent the finish from sagging. Wait four hours for the eucalyptus to dry.
Don't use a dark coloured stain on eucalyptus, or the finish will dry blotchy. Don't use liquid oil stain on eucalyptus, or the finish may dry unevenly. Do not stain or varnish eucalyptus, using a synthetic paintbrush, as oil-based finishes will ruin polyester and nylon bristles.