As good as ipe for decking?

Comparable hardness and durability at lower price. Slightly warmer color. Both excellent choices.

Why won't stain soak in?

Extremely dense. Sand 60-80 grit and use tropical hardwood oils.

Can cumaru be left unfinished?

Yes, weathers to gray and remains sound for decades.

Decking

exterior cladding

flooring

outdoor furniture

boardwalks

pool surrounds

How to Finish Cumaru: Complete Staining & Sealing Guide (2026)

Prepared by Lumberama's Wood Finishing Team

|Last updated June 8, 2026|Sources & methodology

Cumaru, often marketed as Brazilian teak, is one of the hardest commercially available decking woods. Its rich golden-brown color and excellent durability make it a popular and more affordable alternative to genuine ipe.

Key Takeaways

Cumaru, often marketed as Brazilian teak, is one of the hardest commercially available decking woods.
Its rich golden-brown color and excellent durability make it a popular and more affordable alternative to genuine ipe.
Penetrating hardwood oil for tropical species; UV-protective exterior oil.
No film-forming finishes, they will not adhere to the dense surface.
Interlocked, sometimes wavy grain with medium to fine texture.

Wood Characteristics

Interlocked, sometimes wavy grain with medium to fine texture. Diffuse-porous with fine pores. 3330 Janka, extremely hard. Golden tan to reddish-brown with darker streaks. Moderate to high tannin.

Recommended Finishes

Penetrating hardwood oil for tropical species; UV-protective exterior oil. No film-forming finishes, they will not adhere to the dense surface.

Preparation Steps

Sand with 60-80 grit to aggressively open grain. Use carbide sandpaper. Clean with acetone immediately before oiling. Apply finish within 1-2 hours of sanding.

Application Steps

1. Sand 60-80 grit to open pores. 2. Clean with acetone. 3. Apply tropical hardwood oil generously. 4. Penetrate 15-20 min. 5. Wipe off ALL excess. 6. Dry 24-48 hours. 7. Second coat if wood still dry. 8. Usually 1-2 coats.

Maintenance Schedule

Oil: reapply every 6-12 months for color. Weathers to silver-gray in 6-12 months unfinished. Brighten before re-oiling. Lasts 25-40 years without finish.

Common Mistakes

Not sanding aggressively enough; using standard deck stain that sits on surface; film-forming finishes peel; not wiping excess oil creates tacky surface.

Interior vs Exterior

Interior: Extremely durable flooring but very difficult to install and sand. Use hardwax oil or penetrating oil. Exterior: Outstanding for decking. Oil annually or let weather to gray. Pre-drill all holes.