Link to an amendment published at 85 FR 5566, Jan. 31, 2020.

1. (a) Preconditioning. Preconditioning of plywood or particleboard panels for air chamber tests shall be initiated as soon as practicable but not in excess of 30 days after the plywood or particleboard is produced or surface-finished, whichever is later, using randomly selected panels.

   1. (1) If preconditioning is to be initiated more than two days after the plywood or particleboard is produced or surface-finished, whichever is later, the panels must be dead-stacked or air-tight wrapped until preconditioning is initiated.
   2. (2) Panels selected for testing in the air chamber shall not be taken from the top or bottom of the stack.

2. (b) Testing. Testing must be conducted in accordance with the Standard Test Method for Determining Formaldehyde Levels from Wood Products Under Defined Test Conditions Using a Large Chamber, ASTM E 1333-96, with the following exceptions:

   1. (1) The chamber shall be operated indoors.

   2. (2) Plywood and particleboard panels shall be individually tested in accordance with the following loading ratios:

      1. (i) Plywood - 0.29 Ft2/Ft3, and
      2. (ii) Particleboard - 0.13 Ft2/Ft3.
   3. (3) Temperature to be maintained inside the chamber shall be 77° plus or minus 2 °F.

   4. (4) The test concentration (C) shall be standardized to a level (CO) at a temperature (tO) of 77 °F and 50% relative humidity (HO) by the following formula:

      C = CO × [1 + Ax (H − HO)] × e−R(1 / t − 1 / t O)

      where: C = Test formaldehyde concentration CO = Standardized formaldehyde concentration e = Natural log base R = Coefficient of temperature (9799) t = Actual test condition temperature ( ^O K) tO = Standardized temperature ( ^O K) A = Coefficient of humidity (0.0175) H = Actual relative humidity (%) HO = Standardized relative humidity (%)

      The standardized level (CO) is the concentration used to determine compliance with § 3280.308(a).

   5. (5) The air chamber shall be inspected and recalibrated at least annually to insure its proper operation under test conditions.

[49 FR 32012, Aug. 9, 1984, as amended at 58 FR 55009, Oct. 25, 1993; 70 FR 72046, Nov. 30, 2005]