NOTE 8—A study conducted by two separate laboratories investigating
whether heating sulfated ash residues for extended periods of time (for
example, overnight) in a furnace at 775 6 25°C as opposed to 30 min as
required in 9.8 revealed that a significant difference in sulfated ash results
can exist. The study indicated that lower sulfated ash results were obtained
on the samples left in the furnace overnight versus those that were heated
in 30–min cycles. A thermogravimetric analysis also confirmed that the
samples evaluated continued to lose weight at 775°C as a function of time.
As such, it is essential that the 30–min heating time requirement be
adhered to in performing the test method. Details concerning the study can
be found in ASTM Research Report RR:D02-1597.