Answer:
Temperature is not that important in TLC.
Explanation:
The concept of TLC is that a solvent (or mixture of solvents) ascends in a capilary system and the differences in interections between solvent and capilary of the substances present allow their separation.
In this process it's important that the air is saturated with solvent vapor, so the lid is important; the solvent must ascend by the capilar, so making it stedy is important, also making sure the starting line is above the solvent level is crucial for this same reason; using a marker would ruin a experiment because most marker's ink (if not all of them) would be carried by the solvent as well, but carbon is not, so a pencil must be used.