HOT FILTRATION Bantoo will show you how to do the hot filtration step in a crystallization procedure. First he has to show you how to flute filter paper. Scroll down.

FLUTED FILTER PAPER Choose the size filter paper that will just fit into the stemless funnel you will be using. Step #1: At all steps, crease sharply. First, fold the paper in half. Step #2: Fold in half again. Step #3: Fold each quarter in half again, with all creases facing up. Here and in the next step, try to get all the folds to meet at a sharp point.

FLUTED FILTER PAPER STEP #4 Fold each eighth in half again, but this time make the folds in the opposite direction to the one you have been doing.

HOT FILTRATION STEP #1 In an Erlenmeyer flask, preheat the solvent you will be using for the crystallization -- don’t forget a boiling stick or stone. Also set up and preheat the apparatus for hot filtration: 2-3 mL of the solvent in a beaker (with boiling stone), stemless funnel, and fluted filter paper.

HOT FILTRATION STEP #2 A little at a time, add the warm solvent to the solid you are crystallizing. Keep this mixture warm too. Stop adding solvent at the point where no more solid appears to be dissolving and only insoluble impurities remain. You can add 1-2 mL solvent beyond this point to compensate for the evaporation which will occur as you proceed.

HOT FILTRATION STEP #3 Filter the warm solution in large portions. At first you will probably need to hold the filter paper down with a spatula the way Bantoo is doing here.

HOT FILTRATION STEP #4 After you filter the solution, look carefully to see whether crystals have formed in the filter paper. This was the problem here (the transparent crystals don’t show up in the photo). Wash these crystals through with a small amount of the warm solvent. If you add more than a few milliliters solvent at this step, in most cases it would be a good idea to evaporate some off before you go on to the crystallization cooling step.