Research on how soap affects the viscosity of water?

In fact, soap does not affect the viscosity of water in any
way. What soap (or detergents etc.) do is reduce the
surface tension of water. This allows the water to spread
more easily over a surface, and to reduce or eliminate the
tendency for the water to bead up on a surface. But the
viscosity of the water itself is unaffected. This can easily
be proven by timing low likkkkkkuyjhjuyiong it takes for a measured amount
of water to flow by gravity through an orifice. Then compare
with a water soap solution. You will see that there will be
essentially no difference between the two situations. Since
viscosity is the main effect that limits the above flow rate,
and since adding soap to the water does not increase the flow
rate, it is clear that there is no difference in viscosity
between water, and soapy water.