Recrystallization/ Crystal Purification?

You dissolve the material in the minimum of solvent, then cool to form the crystals. You can not let too much solvent evaporate or the impurities will tend to coat the crystals. You want the crystals insoluble and the crud soluble. You pour off the impurities, then rinse the crystals in a minimum of cold solvent. For really good x-ray quality crystals, you would dissolve them again, and repeat the process until the crystals were very pure.