Otherwise fading of the dye as well as softening of the balsam will result. For a demonstration requiring the filter to be in projected beam, place the filter where the power density is least. This usually means near the condenser lens. Never lay the filter down on the table or other dirty surface. Either place vertically in its box or lay on clean soft paper or Kleenex.
Scratches are permanent.
In addition to these cardinal points your courtesy in filing filters in the box in numerical order with numbers at the top facing the same way will be greatly appreciated by the next user. Set up the equipment as for Light-6. Always use the scientifically accepted nomenclature when discussing color. The field of color is confused enough already without your adding to the confusion. Read Light-39 for a most brief summary and at least scan the highlights of the two references given there before trying to instruct people already somewhat confused.