Scope:

Standard method ASTM D6325 describes the procedure to determine open assembly time for a trowelled carpet adhesive. It is important that sufficient assembly time should be available to an installer to prepare and place carpet sections for bonding onto the substrate.  An adhesive with too short an open assembly time will not allow the installer to place the carpet before it completely dries out. Conversely, if the open assembly time is too long, then the adhesive will still be wet and cause movement of the carpet after placement, besides affecting the bond strength. The ASTM D6325 test can aid the adhesive manufacturer and the carpet installer to select the appropriate adhesive for the application.

It is stated in ASTM D6325 that the test method is modelled upon ASTM C679 (test for tack free time of elastomeric sealants). The ASTM D6325 variations relate to substrate, adhesive, the use of rigid LDPE pieces to test the tackiness, the time intervals and use of 1 kg deadweight.

Procedure:

Test specimens, as specified in ASTM D5215 section 8, are marked for identification. They are then heat-aged at 140 ±5 ⁰F for seven days, followed by exposure to UVA light for 48 hours. Thereafter, comparative color measurements between test and control specimens are performed, using a colorimeter or spectrophotometer. The reflectance values measured by the instrument are converted to CIELAB color scale by computation.

Specimen size:

Each LDPE piece will be 2 inch × 2 inch × 0.006 inch.  The glass piece should be 12 inch × 12 inch.

Result:

The ASTM D6325 open assembly time is expressed in minutes.