9. Procedure
9.1 Take each duplicate specimen and separate the coated facing from the combined board as follows:
9.1.1 Pry the facing loose from the medium and peel it back to remove it. This is accomplished conveniently by working from the four corners of the specimen to achieve rather complete removal of the facing. Some thin layers of fibers of the original facing will be left adhering to the glue line and medium and may be ignored. (Set aside or discard the remaining part of the combined board, that is, the medium and second facing.)
9.1.2 Take the removed facing and carefully peel or split it into two sections: (1) a layer that represents the complete area of the coated surface, together with a thin layer of adhering fiber, and (2) the layers representing the main thickness of the wax-saturated facing below the coating. The delaminating operation may involve several peelings of layers to collect the appropriate separate sections.
9.1.3 Combine the appropriate similar sectionings from the duplicate specimens, and cut the larger pieces with scissors into small chips about 25 mm square, being careful to retain all cuttings without loss. Weigh separately to the nearest 1 mg the two accumulated sections - (1) the coated section and (2) the impregnated section.
9.2 Extract each facing section separately as follows:
9.2.1 Place the section pieces in a 1000-ml beaker. Add 250 ml of the solvent 1,1,1-trichloroethane and cover the beaker with a watch glass. Heat to 75°C (167°F) for 1 h on a steam bath or hot plate in a hood. Pour off the solvent, passing it through the stainless steel screen in the funnel to remove fibers, and collect the solvent in a clean, tared 1000-ml beaker. Rinse the extraction beaker and the extracted paper chips with 50 ml of hot solvent, filter this rinsing, and add it to the solvent in the tared beaker.
9.2.2 Repeat the solvent extraction using 250 ml of fresh solvent, boiling for 1 h and rinsing with 30 ml of hot solvent. All extracts and rinsings are combined in the same tared beaker.
9.2.3 Collect all of the extracted paper chips and fibers remaining in the beaker and on the screen, from the extraction of the coated section, and place the fibers in a 250-ml beaker, allow to air-dry for 30 min, dry in an oven at 100°C for 60 min and then equilibrate at 23°C (73°F) and 50 % relative humidity for 24 h. Weigh to the nearest 1 mg and record as fibers from the coated section. (Discard fibers from impregnated section.)
9.2.4 Evaporate the combined solvent extracts from each section on a steam bath in a hood, or optionally, overnight in the air current of a hood. Evaporation may be hastened by use of a stream of nitrogen. For the final stages of evaporation, place the beaker on a hot plate at about 150°C (about 300°F) to dissipate solvent vapors or moisture completely. Confirm that evaporation is complete when no solvent odor can be detected. Cool and weigh the tared beaker. Record the weight of wax extracted to the nearest 1 mg.
10. Calculation
10.1 Calculate the percent of impregnated wax in the facing, a, as follows:
where:
b = weight of sample impregnated section, waxed fibrous layers before extraction, g, and
c = weight of wax extracted from impregnated section, g.
10.2 Calculate the coating wax weight, grams per square metre, i, as follows:
where:
a = percent of impregnated wax in facing
d = specimen area, total of coated surface, m2,
f = weight of wax extracted from coated section, g, and
h = weight of extracted fibers from coated section, g.