Standard Operating Procedure – Wood Protection Group
Name: Water Absorption and Thickness Swell
Date: September 18, 2000
SOP #: 330
Author: Erik D. Keranen\
Supercedes: Revision 1,2
Approved: Glenn M. Larkin\
Scope: This SOP covers specimen preparation, treatment, and measurement for the 2-hour water soak, 24-hour water soak, and non-recoverable thickness swell determinations.
1.1 Cut the test specimen to 75 x 75 mm in size, or per project protocol.
1.2 Condition the specimen in chamber #2 for two weeks.
1.3 Weigh the specimen to the nearest 0.01 grams. Record the data.
1.4 Measure the specimen width, length and thickness to the nearest 0.1 mm. Thickness is measured at the four points 25 mm in from each side at the corners. Use a template for speed and accuracy to mark each measurement point. Record the data and average the four thickness measurements from each specimen for thickness swell calculations.
3.1 After two hours remove the specimens and stand them on edge in a sink for about ten minutes. Pat the specimen surface with a paper towel to remove excess water. Weigh the specimen and obtain the four thickness measurements. Record all data.
3.2 Re-submerge the specimens. Record the time of re-submersion.
3.3 After an additional 22 hours from the time of re-submersion remove the specimens from the water and repeat step 3.1 to obtain 24-hour water soak data.
3.4 Record the ovendry weight.
4.1 Determine the 2-hour thickness swell, 24-hour thickness swell, and non-recoverable thickness swell of each specimen using the following formulas:
TS 2-hour = (T2h–Tic) / Tic * 100
TS 24-hour = (T24h–Tic) / Tic * 100
TS non = (Tfr–Tic) / Tic * 100
Where: TS = % Thickness swell,
T2h = Specimen average thickness after 2 hours submersion,
T24h=Specimen average thickness after 24 hours submersion,
Tfr = Specimen average thickness after final reconditioning, Tic = Initial conditioned specimen average thickness
5.1 Place the specimens in an airflow hood for at least two weeks to approach the pre-soaked original weight.
5.2 Place the specimens in humidity chamber #2 for an additional two weeks to fully recondition to approximately 12% moisture content.
5.3 Record the final weight and thickness measurements.
6.1 Place specimens in an oven at 103°C for 48 hours.
6.2 Determine the 2-hour water absorption and 24-hour water absorption for each specimen using the following formulas:
WA 2-hour = (Wt2h-Wtic) / Wtic *100
WA 24-hour = (Wt24h-Wtic) / Wtic *100
Where: WA = % Water absorption,
Wt2h = Specimen weight after 2 hours of water submersion,
Wt24h =Specimen weight after 24 hours of water submersion,
Wtic = Initial conditioned specimen weight
6.3 Calculate the specimen moisture content after the initial conditioning, and at the time the fully reconditioned specimen measurements are taken:
MCinitial = (Wtic – Wtod) / Wtod *100
MCfr = (Wtfr – Wtod) / Wtod *100
Where: MC = Moisture content (% oven-dried basis),
Wtic = Initial conditioned specimen weight,
Wtod = Oven-dried specimen weight, and
Wtfr = Final reconditioned specimen weight