The question is not about the mixing rule of hetergeneous slags (one liquid + one solid).

It's about the mixing rule of viscosity when two oxide liquids mix.

When the slag compositions hit a region where there is a miscibility gap of two oxide liquids, they should physically mix (or form emulsion that one is suspended in another) as they don't dissolve into each other.

The experiment normally reports a viscosity value, but behind the measurement, what is really this viscosity value for such case - is it the viscosity after mixing or happens to be one of the oxide liquid?

It seems we can easily predict the viscosity of two mixing liquid oxides using the equations in the attached snapshot.

Can I have your opinion on the viscosity mixing rule of two oxide slags or liquids ? How do we model or predict it ?

Thank you in advance.