Species Specs: Cumaru

Dipteryx spp. genus 

The Dipteryx spp. genus is a part of the Fabaceae family. Other names for the species Cumaru include Brazilian teak, tonka, tonka bean, southern chestnut, Brazilian chestnut, almendrillo, ebo, champanha, sarrapia, gaiac de cayenne, and others. This genus of trees grows primarily in northern South America. 

USES
This wood commonly is used in heavy-duty and durable construction applications. Other than being used for wood flooring, it is used even more-commonly as industrial flooring, decking, cabinetry, furniture, piers, railroad crossties, naval and marine construction, bridge building, turnery, tool handles, cooperage, decorative veneers, and more.

COLOR
The wood can vary significantly, from red-brown or purple-brown with light yellow-brown to purple streaks. Most common is a medium to dark-brown color with a reddish to purple underlying hue. After exposure, this species tends to become more of a uniform light-brown to yellow-brown color over time.

GRAIN
Diffuse-porous. The grain can vary from straight to very irregular or interlocked. It is a fine-to-medium texture with a waxy or oily feel. 

HARDNESS (JANKA)
Averages = 3,330

DIMENSIONAL STABILITY
Average once properly dried. 

Cumaru has a dimensional stability factor of 5.3 percent (radial) and 7.7 percent (tangential), meaning this species may shrink/swell up to 7.7 percent of its given width, depending on how it is cut, when going from green (30 percent MC) to oven-dried.  

DIMENSIONAL CHANGE COEFFICIENT
Averages = .00212 (tangential)

SPECIFIC GRAVITY
Averages = 1.09

NAILING
Can be very challenging to work with. The hardness, and interlocked grain of this species makes it very difficult to drive a fastener through. Anything less than 18 gauge fasteners likely will crumple on impact. Heavier gauge fasteners (15.5g – 16g) have a tendency to splinter, fracture, and split the tongues when nailing. The air compressor PSI will need to be reduced to avoid tongue splitting. Use of 18 gauge cleats works best when nailing this wood, but the compressor PSI will require consistent manipulation to find the sweet-spot. Pre-drilling and hand-nailing is common. Glue-assist with a quality wood flooring adhesive is recommended to assist in any nail-down installation, but will require surface preparation (solvent wiping) prior to application due to the high oil content in this wood. 

SANDING
Cumaru is a very hard and very dense wood, which makes it challenging to sand, and requires extra caution with grit progression. Do not skip grits when sanding this wood. The final pass using a hard-plate, a multi-head, or oscillating sander normally is done with a higher grit abrasive than with other species. This species contains silica, and can affect the life of the abrasives. This wood finishes very nicely; however, the oils in this species can react with some finishes. It may be helpful to tack the floor with denatured alcohol prior to any finish application. It is recommended to sand and prepare one room at a time, then apply a sealer immediately to avoid bleedback of the natural oils in this wood. Finishes and stains often require extended dry-times on this species. Occasionally, white spots or specks that were not noticeable before finishing may be apparent once the floor is coated or after the floor has aged. These are spots of calcium carbonate and are a naturally occurring characteristic of this species. 

SUSTAINABILITY
Cumaru is not listed in the CITES appendices, or on the International Union  for Conservation of Nature and Natural Resources Red List of Threatened Species. Know what you are buying, and from whom you are buying.

INTERESTING NOTES

  • This wood is naturally resistant to insect damage and fungi. 
  • This wood has a low fiber saturation point at 22 percent.
  • Cumaru is a common substitution for the ipe species, due to similar appearance and performance characteristics.
  • Cumaru holds a class A fire rating, the same rating given to concrete and steel.
  • The trees can reach a height of up to 120 feet tall and a trunk that can reach up to 5 feet in diameter. 
  • The tonka tree is cultivated for its vanilla-cinnamon scented seeds, also called the tonka-bean. This bean is one of the first artificial vanilla flavoring agents. These seeds contain a compound known as coumarin. 
  • Coumarin initially was used as the precursor to a number of important anticoagulant drugs, including warfarin. 
  • Importation of the tonka bean has been banned in the U.S. by the FDA since 1954, due to the toxicity of the bean when used in high concentrations. 
  • In France, tonka beans are used in cuisine and in perfumes. Yves Rocher uses them in their men’s cologne called Hoggar. 

Sources:  WOOD!; Copyright © 2016, Eric Meier Wood Identification and Use; Copyright © 2006, Terry Porter

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