[Yossarian]

I'm not sure about this question, so I would appreciate any help in answering it.
In carrying out an analysis of a mixture, what do you expect to see when the thin layer chromatography plate has been allowed to stay in the developing chamber for too long, so that the solvent front has reached the top of the plate?  My theory is that all the spots would end up mixed at the top of the plate, rendering the results useless, since Rf values cannot be determined if there is not adequate separation.  Is this correct?  If not, could you explain what would actually occur?  Any help would be greatly appreciated.  Thanks in advance.

[mike]

I think the same thing

[ATMyller]

That's exactly what happens I've managed to mess it up for once myself. And even the spots wouldn't mix badly it's impossible to calculate Rf values because you can't measure the distance of the solvent front anymore.