In oil sands flotation, bitumen is known to release natural surfactants into the process water following the addition of NaOH. These surfactants appear to replace the need for frother. Measuring the Sauter mean diameter (D-32) vs. dilution, it was possible to characterize the frother-like properties of process waters as an equivalent concentration of a known frother commonly used in mineral flotation, DF-250. Process water samples from the thickener overflow at the Shell Albian plant were examined. The study showed equivalent concentrations up to 60 ppm DF-250 and variations between samples. Reasons for the variability are discussed. A gas holdup vs. D-32 correlation was established which reduced the experimental effort. (C) 2013 Elsevier Ltd. All rights reserved.