ASTM D1545 for Viscosity of Transparent Liquids by Bubble Time Method
5. Report
5.1 Report the following information:
5.1.1 The viscosity obtained by the timing method expressed as "bubble seconds" or "approximate stokes".
NOTE 6 - The time in seconds or "bubble seconds" is an approximate measurement of stokes when the bubble time method is applied to most raw materials and finished products encountered by the paint, varnish, and lacquer industries. This relationship does not hold for silicones or water dispersions of gums or similar materials. Viscosity results by this test method are influenced by non-Newtonian behavior and by surface tension. Other variations on bubble-tube viscometers are described in ASTM STP 500, Section 3.2.9.
6. Precision and Bias
6.1 Precision - On the basis of an interlaboratory study of this test method in which ten laboratories tested liquids ranging in viscosity from 4.5 to 440 St, the following criteria should be used for judging the acceptability of results at the 95 % confidence level:
6.1.1 Two results obtained by the same operator should be considered suspect if they differ by more than 4.9 % relative.
6.1.2 Two results, each the mean of duplicates, obtained by operators in different laboratories should be considered suspect if they differ by more than 9.0 % relative.
6.2 Bias - No information can be presented on the bias of this test method because no materials having an accepted reference value is available.
7. Keywords
7.1 Gardner-Holdt; GH viscosity; viscosity
