Press the short-waved button on a UV lamp positioned on a tilt over the TLC plate.
Alternatively view the TLC plate inside a box designed to protect your eyes from UV damage.
The TLC plate will fluoresce green and spots will be dark.
Circle the spots with a pencil.
Further visualize with another method if desired.
In the fume hood, place the TLC plate in a jar containing a few crystals of iodine (or alternatively iodine with silica). Close the lid.
If using the iodine-silica powder, submerge the plate under the powder for a few minutes.
Spots will appear yellow-brown.
Remove the plate and circle the spots as they will fade rather quickly.
Wear gloves and work in the fume hood as many stains are highly acidic or oxidative.
Hold a TLC plate with forceps and quickly dip the plate into and out of the stain jar to cover the area where solvent traveled. Let excess stain drip off, then wipe residue off the back with a paper towel.
Wave a heat gun set to "high" (at first) back and forth over the top of the TLC plate until spots appear.
Turn the heat gun down to "low" if charring begins on the plate.
Further visualization is not possible after a TLC plate has been stained.