A series of polyoxypropylene alkyl ethers, which includes common flotation frothers such as DF-200, DF-250 and DF-1012, have been tested. The "frothing" properties of these compounds were investigated through measuring their effect on bubble size and dynamic foamability index. The tests revealed a definite relationship between the number of propoxy groups in the CH3(OC3O6)(n)OH molecule and the critical coalescence concentration (CCC) values, and the values of the dynamic foamability index (DFI). The results also show a clear correlation between the CCC and DFI values. Such a correlation was earlier reported for the hexanol derivatives. It has been shown when testing frother blends that the molar ratios of blend constituents can be based on the corresponding CCC values of the individual frothers. (C) 2003 Elsevier B.V. All rights reserved.