Wood Identification Procedures

Wood Identification Procedures

Identification process.

Accurate wood identification depends mainly on characteristics of the wood cells revealed under a microscope. First, a cross-sectional surface of the sample is smoothed with a sharp knife and examined with a hand lens. Then small, thin sections are cut freehand along the grain from the radial and tangential surfaces and prepared for viewing under the microscope.

Identifications are usually completed by means of technical anatomical features observed at high magnification. Gross features such as color, odor, and texture are of limited help as they can be quite variable and therefore are less reliable.

Chemical features are sometimes employed in routine identification of wood. The use of DNA technology, once thought to be impossible for wood, is now feasible, though in its infancy. Historically, DNA was extracted only from fresh wood. Modern techniques have allowed extraction from dry material, and it is reasonable to think that the next decade will see the entrance of DNA techniques for the exact identification of some commercially important species of wood. Such techniques are likely to remain expensive, and probably would not be employed for routine identification work.

Limitations.

Identifications based on wood anatomy are generally accurate only to genus (e.g. a species of spruce) or, in some cases, to a subgeneric grouping (e.g., white oak group), but rarely to the exact species. Therefore, all information known about the specimen is important and should be provided with it. The wood's common name, country, or geographic area of origin are especially useful and may help to determine the precise species. For example, the American red pine, the European Scots or Scotch pine, and several Asiatic species of pine belong to the anatomically-defined red pine group. These species cannot be distinguished by their wood characteristics alone. However, if the wood is known to be native to North America, then an exact species can be given because only one species in the red pine group exists in North America--Pinus resinosa, red pine. Without this information, all a wood anatomist could report in this case would be that the sample is a species of pine (Pinus) of the red pine group. Conversely, if the origin of an antique were in question, finding a species of wood in the red pine group would not distinguish American from European or Asian objects.

For more information on wood identification in the context of personal property such as antiques, see the article:

Wiedenhoeft, A.C. 2006. The limits of scientific wood identification. Professional Appraisers Information Exchange. Vol. 4(2): 16.

Note: The full issue of the PAIE is a large (~2MB) download.

Paste this address into your browser:

http://www.isa-appraisers.org/newsletters/ISA_PAIE_Spring2006.pdf

Specimen size.

Specimens 1 X 3 X 6 inches are recommended for purposes of identification. If only small specimens can be supplied for examination, as is generally the case with antique furniture, we will try to provide an identification. We do not identify charcoal samples, nor samples from archaeological contexts except by prior arrangement.

Technique for removal of small samples from valuable wood products.

Small samples must be split from large items rather than shaved or gouged. To produce a good sample, use a sharp knife or small chisel and cut across the grain to a depth of about 3/16 inch. Make two such cuts at least 1/2 inch apart. If a knife is used, a splinter can be split out by prying up at one of the incised points. If a chisel is used, the edge can be placed in one of the cuts and then angled to travel down the grain to the other cut. A sharp tap will produce a good specimen. If the specimen cannot be rolled between thumb and forefinger without crumbling or breaking, do not submit it.

Preparation for shipment.

If more than one sample is submitted, individual items should be clearly labeled. A numerical or alphabetical sequence is simple and effective, with numbers or letters marked directly onto large samples. For small samples, use individual envelopes with the information for the enclosed sample marked on each envelope. Do not tape samples to cards or paper because they can be easily damaged when the tape is removed. Do not place any specimen larger than a toothpick in a normal paper envelope; such packaging is frequently damaged by the postal service mail processing machines. Use a padded envelope or small box instead. Samples submitted without letters will not be identified. If you require delivery confirmation, send your request via a carrier that can provide such information to you (such as registered mail). Requests submitted with self-addressed envelopes (with or without postage) will spend less time in the paper shuffle and thus tend to be returned more quickly.

Determination of origin.

In many cases, wood anatomical identifications cannot provide information regarding the origin of an item. However, wood used in an object may indicate source of manufacture. In furniture, the woods used for the interior parts will usually be the most significant. Often, exterior showy parts are of expensive imported woods, but corner blocks and drawer sides or backs are of less expensive local species.

Certain commonly used American woods such as yellow-poplar, red gum, and tupelo are not native to Europe. Thus, the presence of such woods in an item strongly suggests American manufacture, provided that Asian manufacture can be ruled out. We reiterate that most woods cannot be identified to species, but only to genus or general type (see Limitations).

Commonly used furniture woods such as birch or white oak grow in many different parts of the world. Because these woods cannot be identified to species, their presence in an item does not help determine where it was produced.

Age determination.

No attempt is made at this Laboratory to ascertain or even approximate the age of antique pieces or ancient wood specimens. The well-known radiocarbon-14 dating process is not feasible for determining the age of antiques, bearing trees, or other relatively‘recent,’ non-archaeological wood.

Number of Samples

The Center for Wood Anatomy Research will identify a maximum of five wood samples per household or business per calendar year as a free public service to U.S. citizens. We try to accommodate inquiries from non-citizens, but such requests are typically assigned a low priority. The Center for Wood Anatomy Research is unable to identify more than five specimens per year. Persons or businesses in need of more than five identifications per year will need to find a private consultant to provide this service.

Duration of Process

Wood identifications can take anywhere from 5 minutes to many hours, depending on the type of wood, the size and quality of the sample, the information provided with the sample, and several other factors. Generally, identifications will be completed 2-4 weeks following receipt of the sample for temperate woods and 2-6 weeks for tropical woods. Responses are hand-written on the letter sent with the request. Samples are held for 3 months and then discarded; small samples are often destroyed in the process and are not retained. .

Send your samples to:

Center for Wood Anatomy Research

USDA Forest Service, Forest Products Laboratory

One Gifford Pinchot Dr.

Madison, WI 53726-2398

Contact Us

Direct all questions regarding the identification of woods foreign and domestic to: woodidentification@fs.fed.us

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			Wood Identification Procedures

	Identification process.		Accurate wood identification depends mainly on characteristics of the wood cells revealed under a microscope. First, a cross-sectional surface of the sample is smoothed with a sharp knife and examined with a hand lens. Then small, thin sections are cut freehand along the grain from the radial and tangential surfaces and prepared for viewing under the microscope. Identifications are usually completed by means of technical anatomical features observed at high magnification. Gross features such as color, odor, and texture are of limited help as they can be quite variable and therefore are less reliable. Chemical features are sometimes employed in routine identification of wood. The use of DNA technology, once thought to be impossible for wood, is now feasible, though in its infancy. Historically, DNA was extracted only from fresh wood. Modern techniques have allowed extraction from dry material, and it is reasonable to think that the next decade will see the entrance of DNA techniques for the exact identification of some commercially important species of wood. Such techniques are likely to remain expensive, and probably would not be employed for routine identification work.

	Limitations.		Identifications based on wood anatomy are generally accurate only to genus (e.g. a species of spruce) or, in some cases, to a subgeneric grouping (e.g., white oak group), but rarely to the exact species. Therefore, all information known about the specimen is important and should be provided with it. The wood's common name, country, or geographic area of origin are especially useful and may help to determine the precise species. For example, the American red pine, the European Scots or Scotch pine, and several Asiatic species of pine belong to the anatomically-defined red pine group. These species cannot be distinguished by their wood characteristics alone. However, if the wood is known to be native to North America, then an exact species can be given because only one species in the red pine group exists in North America--Pinus resinosa, red pine. Without this information, all a wood anatomist could report in this case would be that the sample is a species of pine (Pinus) of the red pine group. Conversely, if the origin of an antique were in question, finding a species of wood in the red pine group would not distinguish American from European or Asian objects. For more information on wood identification in the context of personal property such as antiques, see the article: Wiedenhoeft, A.C. 2006. The limits of scientific wood identification. Professional Appraisers Information Exchange. Vol. 4(2): 16. Note: The full issue of the PAIE is a large (~2MB) download. Paste this address into your browser: http://www.isa-appraisers.org/newsletters/ISA_PAIE_Spring2006.pdf

	Specimen size.		Specimens 1 X 3 X 6 inches are recommended for purposes of identification. If only small specimens can be supplied for examination, as is generally the case with antique furniture, we will try to provide an identification. We do not identify charcoal samples, nor samples from archaeological contexts except by prior arrangement.

	Technique for removal of small samples from valuable wood products.		Small samples must be split from large items rather than shaved or gouged. To produce a good sample, use a sharp knife or small chisel and cut across the grain to a depth of about 3/16 inch. Make two such cuts at least 1/2 inch apart. If a knife is used, a splinter can be split out by prying up at one of the incised points. If a chisel is used, the edge can be placed in one of the cuts and then angled to travel down the grain to the other cut. A sharp tap will produce a good specimen. If the specimen cannot be rolled between thumb and forefinger without crumbling or breaking, do not submit it.

	Preparation for shipment.		If more than one sample is submitted, individual items should be clearly labeled. A numerical or alphabetical sequence is simple and effective, with numbers or letters marked directly onto large samples. For small samples, use individual envelopes with the information for the enclosed sample marked on each envelope. Do not tape samples to cards or paper because they can be easily damaged when the tape is removed. Do not place any specimen larger than a toothpick in a normal paper envelope; such packaging is frequently damaged by the postal service mail processing machines. Use a padded envelope or small box instead. Samples submitted without letters will not be identified. If you require delivery confirmation, send your request via a carrier that can provide such information to you (such as registered mail). Requests submitted with self-addressed envelopes (with or without postage) will spend less time in the paper shuffle and thus tend to be returned more quickly.

	Determination of origin.		In many cases, wood anatomical identifications cannot provide information regarding the origin of an item. However, wood used in an object may indicate source of manufacture. In furniture, the woods used for the interior parts will usually be the most significant. Often, exterior showy parts are of expensive imported woods, but corner blocks and drawer sides or backs are of less expensive local species. Certain commonly used American woods such as yellow-poplar, red gum, and tupelo are not native to Europe. Thus, the presence of such woods in an item strongly suggests American manufacture, provided that Asian manufacture can be ruled out. We reiterate that most woods cannot be identified to species, but only to genus or general type (see Limitations). Commonly used furniture woods such as birch or white oak grow in many different parts of the world. Because these woods cannot be identified to species, their presence in an item does not help determine where it was produced.

	Age determination.		No attempt is made at this Laboratory to ascertain or even approximate the age of antique pieces or ancient wood specimens. The well-known radiocarbon-14 dating process is not feasible for determining the age of antiques, bearing trees, or other relatively‘recent,’ non-archaeological wood.

	Number of Samples		The Center for Wood Anatomy Research will identify a maximum of five wood samples per household or business per calendar year as a free public service to U.S. citizens. We try to accommodate inquiries from non-citizens, but such requests are typically assigned a low priority. The Center for Wood Anatomy Research is unable to identify more than five specimens per year. Persons or businesses in need of more than five identifications per year will need to find a private consultant to provide this service.

	Duration of Process		Wood identifications can take anywhere from 5 minutes to many hours, depending on the type of wood, the size and quality of the sample, the information provided with the sample, and several other factors. Generally, identifications will be completed 2-4 weeks following receipt of the sample for temperate woods and 2-6 weeks for tropical woods. Responses are hand-written on the letter sent with the request. Samples are held for 3 months and then discarded; small samples are often destroyed in the process and are not retained. .
	Send your samples to:		Center for Wood Anatomy Research USDA Forest Service, Forest Products Laboratory One Gifford Pinchot Dr. Madison, WI 53726-2398
	Contact Us		Direct all questions regarding the identification of woods foreign and domestic to: woodidentification@fs.fed.us