Materials needed: filter paper, 250 mL or 400 mL beaker, developing solvent, watch glass

1. Cut one side off a piece of filter paper so that it is flat and use it to line part of the inside of a 250 mL or 400 mL beaker so that the flat edge is at the bottom.

2. Add 5 mL of the developing solvent to the beaker and swirl it around so that the air is saturated with solvent vapor.

3. Cover the beaker with a watch glass (and only remove it when adding or removing a TCL plate).