Substitution is the practice of processing public timber while at the same time exporting unprocessed private timber.

Direct substitution is prohibited. If a company meets the following criteria, they are considered a substitutor and cannot purchase public timber: 

• The company owns and operates a processing facility.
• The company exports unprocessed private timber from land in the state of Washington.
• The company owns or has exclusive rights to harvest timber from such lands for more than seven years.