The Hidden Risk in Some Reclaimed Wood
Most reclaimed lumber was never chemically treated — the barns, warehouses, and homes it came from used untreated wood for the vast majority of their structural and finish components. But some reclaimed wood, particularly from industrial, agricultural, and marine applications, may have been treated with chemical preservatives that can pose health and environmental risks.
The three most common preservatives found in older reclaimed wood are creosote, chromated copper arsenate (CCA), and pentachlorophenol. Each has distinct characteristics that help with identification, and each requires different handling if encountered.
Creosote
What It Is
Creosote is a dark, oily preservative distilled from coal tar. It was widely used from the mid-1800s through the present (it is still used for some utility poles and railroad ties) to protect wood from decay and insect damage in ground-contact and marine applications.
How to Identify It
Creosote-treated wood is usually easy to identify. It has a distinctive dark brown to black color, an oily surface that may still feel tacky, and a strong, unmistakable coal-tar odor. The treatment penetrates deeply into the wood, so even sanding or planing will not remove the characteristic color and smell.
Common Sources
Creosote-treated reclaimed wood most commonly comes from railroad ties, utility poles and crossarms, marine pilings and dock timbers, and industrial warehouse foundations. These applications are well-known to the reclaimed lumber community, and reputable suppliers avoid them for interior and residential use.
Health Concerns
Creosote is a known carcinogen. Skin contact can cause burns and rashes, and prolonged inhalation of creosote vapors is a health risk. Creosote-treated wood should never be used indoors, for food-contact applications, or in any location where people will have direct skin contact with the surface. It should never be burned — the smoke from burning creosote-treated wood is highly toxic.
Chromated Copper Arsenate (CCA)
What It Is
CCA is a waterborne wood preservative that was the standard pressure treatment for residential lumber from the 1970s until 2004, when the EPA banned its use for most residential applications due to arsenic leaching concerns. It was used extensively for decks, playground equipment, picnic tables, and other outdoor residential wood products.
How to Identify It
CCA-treated wood has a characteristic green tint when fresh, but this color fades to gray or brown with weathering. Older CCA-treated wood may be indistinguishable from untreated wood by color alone. Look for the end-tag stamp or inkjet marking that indicates treatment — though these marks may be missing on older or reclaimed material.
Chemical test kits are available that can detect the presence of arsenic on the wood surface. These kits use a swab that changes color in the presence of arsenic compounds. For any reclaimed wood of uncertain provenance that will be used for food gardens, children's play areas, or other sensitive applications, a CCA test kit is a worthwhile investment.
Health Concerns
The primary concern with CCA-treated wood is arsenic — a toxic heavy metal that can leach from the wood into surrounding soil and water. CCA-treated wood should not be used for raised garden beds, children's play structures, picnic tables, countertops, or any food-contact application. Sawdust from cutting CCA-treated wood contains arsenic and should not be inhaled; wear a respirator and work outdoors when cutting.
Pentachlorophenol (Penta)
What It Is
Pentachlorophenol is an oil-borne preservative that was widely used from the 1930s through the 1980s for utility poles, fence posts, and industrial timbers. Its use has been restricted since 1984 to certified pesticide applicators, and it is rarely encountered in residential construction.
How to Identify It
Penta-treated wood often has a dark, oily appearance similar to creosote but with a different, more chemical odor. The treatment can leach a dark, oily residue, particularly in warm weather. Like creosote, it is most commonly found in utility poles, heavy industrial timbers, and agricultural posts — applications where severe decay hazards required aggressive preservation.
How We Handle Treated Wood at Norfolk Lumber
At Norfolk Lumber, identifying and excluding treated wood is a fundamental part of our quality control process. Every load of incoming material is inspected for signs of chemical treatment before it enters our inventory. Our inspection protocol includes visual examination for treatment indicators (color, oiliness, surface residue), olfactory assessment (creosote and penta have distinctive odors that experienced handlers recognize immediately), source documentation review (we record the type and use of every source structure), and chemical testing for material of uncertain provenance.
Any wood identified as chemically treated is rejected from our standard inventory. It is never mixed with untreated material, and it is never sold for interior, residential, or food-contact applications.
What Customers Should Do
- Buy from reputable suppliers who can document the provenance of their material and who actively screen for treated wood.
- Ask about sourcing. If the wood came from railroad ties, utility poles, marine pilings, or industrial ground-contact applications, assume it was treated until proven otherwise.
- Test when in doubt. CCA test kits are inexpensive and available online. If you have reclaimed wood of unknown origin and plan to use it for food gardens or children's areas, test it.
- Never burn unknown reclaimed wood. Burning treated wood releases toxic compounds into the air. If you are unsure whether reclaimed wood has been treated, dispose of it through proper waste channels rather than burning it.