The interaction of foam with textile substrates has been investigated, starting with an attempt to describe the flow of foam in textile–like substrates. This was done by separately evaluating rheology and pressure–drop data. The influence of bubble size was found to be particularly important. In a coaxial cylinder viscometer the viscosity was found to be inversely proportional to bubble size. This finding could not be used to describe the pressure drop of foam flow through flat metal screens according to the d'Arcy equation. Equations could not be satisfactorily derived to describe phenomena such as bubble deformation and diminution, but empirical determination of these parameters could be achieved for each combination of foam and substrate.

An attempt has been made togain a greater insight into the interaction between foam and a moving textile substrate. The effects of changing wet pick-up, fabric velocity, liquid viscosity, foam density and mode of application on penetration have been studied. Application from a closed system makes it possible to apply an exact amount of liquid, and reflectance measurements revealed that between 10 and 60% wet pick-up the actual level of wet pick-up is of major importance. The amount of liquid available determines the likelihood of capillary transport. The results obtained in terms of fabric speed and foam density still leave questions to be answered on the mechanisms of foam flow and degradation in the textile.

A simple rheological model has been used to describe foam flow through moving textile assemblies. The validity of this model was tested, and the nature and the relative magnitude of deviations from the model evaluated for several different substrates. Neglecting foam degeneration during transport, the model was found to represent a valuable means of evaluating some rheological and geometrical deviations. The model can be used in a semi‐quantitative way to describe absorbency during foam application. Liquid absorption experiments done off‐line, absorption during foam application and some earlier results could be described using different theoretical approaches. Some rheological anomalies have been discussed.