Procedure for cleaning the PRISM front lens when it is really bad.

This procedure should probably be used only when hard mineral deposits have
accumulated over periods of high humidity and frosting on the front lens. Normal
cleaning should be a drag of acetone across the lens.

• Make up three bowls of solutions

1. 70% distilled water 30% ethanol
2. 100% pure ethanol
3. 100% pure acetone

• Have the UHP dry nitrogen bottle close by to help dry things off.

• Using the optical wipes or the absorbond pads, I recommend the absorbond pads they seem
  to hold better to the lens during cleaning. In relatively good progression do the following.

1. Blow off the lens with the UHP nitrogen
2. Wipe the lens with the water ethanol solution
3. Wipe the lens with the pure ethanol solution
4. Wipe the lens with the acetone

• Repeat this process as necessary.

By the time that you get to the acetone the liquid will be evaporating pretty quickly. It likely
that there will be water spots left during the first one or two times that you go through this.