Rimu is a New Zealand native timber that was widely used for furniture through much of the twentieth century. Its reddish-brown color and figured grain make older pieces attractive. It also needs a careful approach, because many pieces have dark stain or old shellac, and the surface is easy to sand through.
What rimu is
Rimu (Dacrydium cupressinum) is a New Zealand native podocarp. Botanically it is a softwood, a conifer, even though it is fairly hard and stable in use. The heartwood is reddish-brown with streaky, figured grain, and the sapwood is paler.
Rimu darkens and turns more amber with age and light. Areas covered by objects, such as the space under a lamp base, often stay lighter. Keep that in mind before you decide how much finish to remove.
Identify the finish first
Older rimu pieces were often finished with shellac, applied as French polish, or with nitrocellulose lacquer. Later pieces sometimes have polyurethane. Many pieces from the 1920s to the 1950s carry a dark stain, which owners often want removed to show the natural red-gold color.
Test the finish on a hidden spot:
- Denatured alcohol softens shellac.
- Lacquer thinner softens lacquer.
If neither solvent softens the finish, it is probably polyurethane or another tougher finish, and it will need a stripper or sanding.
Try reamalgamating shellac before stripping
Shellac finishes can often be revived rather than stripped. Reamalgamation means re-flowing the existing shellac with denatured alcohol, so it softens and blends back together. This can hide scratches and dull patches without removing the old finish.
Reamalgamation works only on shellac and lacquer. It doesn’t work on polyurethane, varnish or catalyzed finishes. Test on a hidden area first, because too much alcohol can soften the surface further than you want.
Dealing with dark stain
Dark stain may have soaked into the grain, so stripping and sanding may not remove all of it. You might lighten the piece without fully removing the stain, or accept some shadow in the grain as part of its character. Test a small area before you commit to stripping the whole piece, because a full strip to raw wood is often more work than it’s worth.
Light sanding to protect the patina
Rimu sands cleanly, but the patina, the mellow surface that builds up with age, is worth protecting. Sand lightly, starting around 120 grit, then 150, then 180. Don’t skip more than one grit. Light sanding also protects veneer, and many rimu pieces have veneer on tops or panels. Can I just sand varnished wood? covers the same care with veneer in more detail.
Finish choices and how rimu changes color
Common finishes for rimu include shellac, oils such as Danish or tung oil, and satin water-based or oil-based polyurethane.
The finish you choose changes the color. A water-based clear finish keeps rimu lighter and closer to its natural tone. Oil-based finishes and oils add an amber warmth. Test on a scrap or a hidden area before you finish the whole piece, and check the result in the light where the piece will live.
Repairs and new timber
Patch or replacement timber usually looks lighter when first fitted. It darkens over the following months as it ages and reacts to light. If you add a patch, plan the finish with that in mind, and allow time before you judge the final match.
Sourcing rimu
Supply is limited. Logging of native rimu on public land ended around 2002, and new rimu now comes mainly from recycled timber or sustainably managed private forest. If you need timber for a repair, ask suppliers where it came from. Salvaged or recycled timber is often the most practical option.
Safety
Old dark-stained or painted pieces may have lead-based paint in the layers. Test before you sand, scrape or heat them. Wear a dust-rated respirator when sanding, and ventilate well when you use solvents such as denatured alcohol or lacquer thinner. Both are flammable, so keep them away from flames and sparks.