Sinking time

Submersion Test Sinking Time or Immersion Time... 

Figure 18.7 Sinking time as a function of surfactant concentration.

It should be noted that a reduction of y v uot always accompanied by a simultaneous reduction of yg. and hence it is necessary to obtain information on both interfacial tensions this, in turn, means that measurement of the contact angle is essential in the selection of wetting agents. Measurements of ygL and y y should be carried out under dynamic conditions (i.e., within very short times). In the absence of such measurements, the sinking time (as described above) could be applied as a guide for wetting agent selection. 

The intrinsic affinity of fibers for water is easily quantified by measuring the sinking time of a piece of fabric carefully deposited on water. A better alternative is the dye wicking method in which a fabric strip is suspended with the extremity dipping in a 0.05% aqueous solution of methylene blue. The rise of the liquid is recorded as a function of time and compared to that of a control without softener. 

TABLE 6-2 Wetting Efficiencies of Surfactants in Aqueous Solution (Concentrations for 25 s Sinking Time at 25° C in Draves Test)... 

FIG. 9 Relationship between the hydrophobicity and the wetting ability (sinking time) of the sodium salt of iV-lauroyl-L-amino acids 0.25%, 40°C by semimicro-disk method. (From Ref. 49.)... 

AS 2836.5-1998. Methods of testing surgical dressings surgical dressing materials — Method for the determination of sinking time. 

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