Tulipwood

Several tree species share the name "tulip tree":

• The African tulip tree
• The American tulip tree
• The Chinese tulip tree
• The tulip laurel

Tulipwood — introduction and origin

The American tulip tree, of the Magnoliaceae family, is one of the two species of the genus Liriodendron. Its botanical name is Liriodendron tulipifera (from the Greek leiron, "lily", dendron, "tree", and the Latin tulipiferus, "tulip-bearing").

The natural range of this hardwood lies in the eastern part of the United States, at altitudes varying from 300 metres in the north to 1,350 metres in the south. In France, the first seeds were planted in 1732 at the Petit Trianon in Versailles.

It is a light-demanding tree, favouring mineral-rich, slightly acidic soils that are deep and well drained in areas of high rainfall. It is found in association with black walnut and white oak.

The tulip tree reaches a height of 50 metres in America, rarely more than 30 metres in other countries, with a diameter sometimes exceeding two metres.

Logs of up to 10 metres are obtained from it. Its bole is straight and slightly tapering. The bark, fissured at maturity, is ash grey. Its lifespan is estimated at 400, even 500 years.

Tulipwood — appearance

The American tulip tree has narrow, cream-white sapwood (wider or narrower according to growth rate). The heartwood is matt, with a colour ranging from pale yellow-brown to olive green and white or blackish veining. Note that drying and exposure to light darken this relatively well-figured wood to brown.

The wood is even, with a medium to fine texture, a straight and uniform grain, and it may contain light red staining. Its average density is 0.40 to 0.50 at 12% moisture content.

Tulipwood — main characteristics

The American tulip tree is classed as light and soft. Its total volumetric shrinkage is medium (13%). It is a wood with little movement in relation to its dimensional variations and to changes in moisture content.

Its mechanical properties are average given its density, and it is fairly elastic and not very prone to splitting.

Tulipwood — applications

Tulipwood is used for making furniture (units and cabinets), interior joinery, turned components and cabinetmaking products. It is used, among other things, for kitchen cabinets, doors, mouldings, panelled boards, cladding and panelling. Its uniformity and good stability allow it to be converted into quality veneers (when sliced, quarter-slicing or rotary cutting is preferred).

Note that the good average size of the logs allows large sawn dimensions, suited to joinery and moulding work. It is also used for making musical instruments (lutherie and pianos), gun stocks, sculptures and other turned objects.

Tulipwood — advice on use and finishing

Drying American tulipwood is quick and causes few surface checks and splits. Its stability in service is very satisfactory. With tools intended for softwoods, machining involves no specific constraints. Sawing and slicing are carried out without major problems. Yields are acceptable, better with American than with European timber.

It nails and screws easily (though with some risk of splitting) and offers an excellent finish after sanding. The wood glues without difficulty. It takes pigment and varnish well, which allows an even colour to be achieved.

Tulipwood — the breakthrough of heat-treated tulipwood

For several years now, heat-treated tulipwood has been growing in use. Like poplar, beech, ash or oak, heat-treated American tulipwood is intended for exterior use (cladding) or for flooring. It is today offered by a few plants in France. This type of treatment, akin to pyrolysis, consists in raising the temperature of the wood gradually in an atmosphere with controlled oxygen and humidity.

To prevent the wood from igniting, steam or nitrogen is injected during the heating cycle, which permanently modifies its macromolecular compounds (breakdown of hemicelluloses, cross-linking of lignins and modification of the crystalline structure of cellulose).

Tulipwood — dimensions and commercial grades

Tulipwood imported from the United States is graded according to the NHLA rules. The top grades (with only minimal differences between them), Prime Export, F.A.S. or F.A.S. 1, guarantee a very high yield of knot-free wood and account for most of the timber imported into France (to find out more about the grading rules, please contact us).