Isenberg has a nice chapter on draining in soap-films.  The book is a bit old, and there have been some advances in the current understanding of the mechanics involved; still, this chapter should serve as a nice reference.  It was certainly a great starting point for me in trying to understand what is going on.

Here are some highlights from this chapter, as well as a few thoughts that occurred to me. 

p. 32 - A detailed analysis of how to determine film thickness from light intensity and interference patterns.  This should be easy enough to implement if we need to.

p. 44 - There are 3 types of draining behavior based on the characteristics of the soap film:

1. rigid film, i.e. immobile - the walls of the soap-film do not move.   Draining is primarily due to viscous flow of a thin film between rigid walls.  Evaporation may play a role as well.
2. simple mobile - the walls of the film are mobile.  The main causes of draining are marginal regeneration and gravity convection.  Viscous flow is likely present as well, but on a much slower time scale. 
3. irregular mobile - like simple mobile, except includes erratic behavior of black film region.  Here, "rivers" of black film break into the colored film.

Note: this idea of different draining mechanisms apparently opens up a huge area of unknowns and controversy.  Marginal regeneration is by no means a simple mechanism nor is it completely understood nor is it even understood when it should be applicable (as far as I can tell). 

I think we have a great opportunity to shed some light on this subject.

Note also that marginal regeneration, in any case, occurs at the borders.  Hence, geometry plays a large role in this.  In particular Isenberg notes:

p. 46 - "If we examine the draining of a vertical cylindrical film with no vertical border, the draining and thinning process will be appreciably reduced."

This might be an interesting area to explore - how does our experiment differ if we have a flat soap film with vertical borders?

p. 47 - There are two types of black film: common black film is roughly 30 nm thick.  If evaporation is allowed, Newton black film occurs, roughly 5 nm thick.  It seems that our experiments should lead to the latter, since we have done nothing to prevent evaporation.  In this case, we can likely surmise that no magnetic particles will exist within the black film, since the mag. particles are close to 10 nm in diameter.  This is probably going to be an important point.

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