5.1 Adhesives are classified as dry use or wet use. Each classification includes consideration of short-term in-transit exposure conditions at elevated temperatures up to 220°F (104°C).

5.2 The initial development of Specification D3110 was based on finger-joint assemblies made under controlled laboratory conditions. In the development of this revised specification the results obtained with laboratory-made specimens (see 12.1.2) were compared to those obtained with industrially manufactured specimens (see 12.1.1). These finger joints were prepared using previously certified adhesives in cooperation with a manufacturer or equipment supplier who had the necessary finger-joint cutter and assembly equipment. These finger joints may vary in geometry and length from manufacturer to manufacturer, and this variation could affect the performance of the bonded-finger-joint assembly.⁵ (See 12.1, 12.4, and 12.5.) Fig. 3 depicts a sample finger-joint configuration.

5.2.1 When changes are made in the design of the industrially manufactured finger joint, the new design should be compared to a control design that has been used successfully.

5.3 An industrially manufactured finger joint should be evaluated using the requirements for compliance with this specification, in accordance with 4.1. When this specification is used to evaluate specimens made from field-manufactured assemblies, the results may not compare favorably with those run on specimens made from laboratory-made assemblies.

5.4 Test requirements are provided to determine if the adhesive is suitable for dry use or wet use.

5.5 The dry test and exposure conditions and treatments are to evaluate adhesives used in nonstructural finger joints for typical service conditions.

5.5.1 The 220°F (104°C) test, a more severe test, is designed to evaluate the product after exposure to short-term elevated-temperature conditions. This test is intended to simulate conditions that might be experienced in transit, further processing, or in-service conditions.

Note 4-These typical service conditions could include stress and time under stress, as well as elevated temperature.

5.6 Procedures are described in sufficient detail to permit duplication in different testing laboratories.

5.6.1 Record any deviations in these procedures on the report forms, Appendix X1, as it may have an impact on the results obtained. Test data are only valid for the length and design used. (See 12.4.)

5.7 To avoid potential problems that would be caused by interrupting the bonding process, the adhesive-performance level should be determined by the finger-joint manufacturer prior to handling and early shipment. Before beginning the full testing process, the testing laboratory should pull a representative sample and check the dry strength first, in order to ensure that the product basically conforms with the performance level certified by the adhesive manufacturer.

TEST METHODS

This specification establishes the performance levels for adhesives to be used in finger joints in nonstructural bonded-lumber products. Such products include, but are not limited to, interior and exterior mouldings, window and door components or parts, and bonded-lumber panels. The apparatus shall consist of environmental chamber for moist-heat aging, oven with sufficient air circulation to remove moisture from the chamber, tanks for soaking and boiling, testing machines for the flexure and tension specimens, and vacuum-pressure vessel. Tests shall be conducted such as dry, soak, elevated-temperature, and temperature-humidity tests for dry-use classification and dry, boil, elevated-temperature, and vacuum-pressure tests for the wet-use classification. The adhesives shall be tested for performance which shall meet the following requirements: moisture content; specific gravities of wood species; tensile strength; wood failure for soft and hard woods; and rupture modulus.