Cleaning, washing or pressing paper money is generally harmful and reduces both the grade and the value of a note. At the very least, a washed or pressed note may lose its original sheen and its surface may become lifeless and dull. The defects a note had, such as folds and creases, may not necessarily be completely eliminated and their telltale marks can be detected under a good light. Carelessly washed notes may have white streaks where the folds or creases were (or still are). Processing of a note which started out as Extremely Fine will reduce it at least one full grade. Glue, tape, or pencil marks may sometimes be successfully removed. While such removal will have a cleaned surface, it will improve the overall appearance of the note without concealing any of its defects. Under such circumstances, the grade of the note may also be improved. One should not iron a banknote to remove creases and folds. The heat can cause the colour of the note to change or flow and thereby destroy patterns. Folds and creases are part of life of a bank note and should therefore be accepted as such. Any kind of tape should not be used in repairing a banknote. Chemicals that are used on the tape can damage the banknote and its grade will be severely reduced or even make it worthless. Ink and stains can sometimes be removed by using soap, water or alcohol. The treated banknote has to be be washed with clean water after any treatment. Afterwards it should be dried, which can be done by pressing it between paper sheets (in a book). Now when it comes to professional bank note cleaning and improving techniques we are not a good advisor to you since we do not clean, wash, press or improve any banknotes in any way other than straightening bent corners and folds with a finger and naturally "pressing" the notes in plastic holders while they are stored in a stock box. Only experts, called paper conservators, should repair paper money.
Hope this helps a little
FRIEDSQUID
Canadian Paper Money
