Re: Stomates

	I must admit that I am not familiar with the nail polish/tape 
technique you mention.  I will assume that it strips off the epidermis, and 
this is what you are looking at under the microscope, rather than just a 
replica of the leaf's surface.  If this is indeed the case, I could easily 
imagine that the exposed guard cells would become dehydrated and lose their 
turgor, thus appearing to close the stomates.  Are you looking at the peel 
under a cloverslip, or simply on a slide exposed to the air.  If the later, 
you might use a coverslip, and try adding different liquids, e.g. water and 
various concentrations of NaCl, to see how this affects the stomatal 
closure.