Section 7 of AWPA Standard M-4 from 2008 describes preservation systems for field treatment of wood:

"The appropriateness of the preservation system for field treatment shall be determined by the type of preservative originally used to protect the product and the availability of a field treatment preservative. Because many preservative products are not packaged and labeled for use by the general public, a system different from the original treatment may need to be utilized for field treatment. Users shall carefully read and follow the instructions and precautions listed on the product label when using these materials."

Copper Naphthenate preservatives containing a minimum of 2.0% copper metal are recommended for material originally treated with copper naphthenate, pentachlorophenol, creosote, creosote solution or waterborne preservatives. Use of copper naphthenate preservatives with a minimum of 1.0% copper metal is appropriate in those regions of the country where the higher concentration material is not readily available.

Inorganic Boron preservatives are limited to use in applications not in contact with the ground and continuously protected from liquid water. They may be used for field treatment of material originally treated with any waterborne treatment as long as this condition is met. Solutions shall have a minimum concentration of 1.5% (B2O3 basis).

Copper Naphthenate is the best wood preservative available to contractors and do-it yourself consumers. It is perfect for use when wood will be in contact with the ground and as an end cut treatment when you cut pressure treated wood.

Copper naphthenate is available at many building supply stores and hardware stores.


For customers who need smaller quantities (500 gallons or fewer), please contact CopperCare or Poles Inc.:

Copper Naphthenate – Copper Care Wood Preservatives


For customers that need large quantities (500 gallons or more) contact Sandy Stalans at 800-264-0870 or Nisus offers the following products:

RTU Copper Naphthenate
Oil-based 1% Cu active

RTU Copper Naphthenate
Oil-based 2% Cu active

RTU Copper Naphthenate
Water-based 1% Cu active

Liquid DOT for end cut treatment of pressure treated wood used in the interior of structures. PenaShield can also be used as a general wood preservative outdoors if wood will be painted or stained and on any interior wood.