When handling optics, always wear soft, non-absorbent, lint-free gloves. Please observe the following procedure when cleaning these viewports:

• Always start by blowing off window first with clean, dry compressed air. This will remove any potentially hard, gritty dust that could cause scratching during cleaning.
• Always use a solvent-dampened swab to wipe clean a window, a dry swab can potentially scratch a window and in any event will leave more than it cleans if not damp.
• Excess solvent should be flung off by a flip of the wrist. If the swab is heavily soaked with solvent, the window will rapidly chill due to solvent evaporation; this will result in water condensation from the air. It may cause spotting or delays in cleaning. It is best to flip off the excess before touching the window with the swab. Alternatively, one can daub the swab on a piece of lint-free tissue to partially remove solvent.
• Compressed air in a can, if tipped upside down or violently shaken, will cause solvent to spray out with the air. No canned duster is perfect. Occasionally some solvent will contaminate the window. The best solution is to use a regulated supply of commercial dry compressed nitrogen gas from a welding gas supply company.
• Always handle the window with protected hands. Powder-free vinyl gloves work best; but, if touched with acetone they can dissolve and leave residue on the window. One should carefully avoid contacting the cleaning swab directly with the glove during the cleaning procedure.