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OPTICAL SURFACE CLEANING PROCEDURE
by John Hudek
Supplies: Distilled water, Ivory liquid, acetone, 3”-5” medical roll cotton, trigger spray bottle, lab nozzle bottle – polyethylene only, soft white face cloth, 1” roll of masking tape.
Part #1. Remove optics from telescope and carefully clean the back, edge sidewall and bevel of each optic using water and a clean soft cloth. The diagonal may be rinsed using tap water instead of wiping with a cloth. Place the primary optic on a large sturdy work table in the vertical position and trigger spray the optic from top to bottom several times with distilled water to loosed and remove dirt. You may want to place a towel under the optic for this. For optics 16” and larger, have someone help you. Next, place the optic in the horizontal position, face up, on the 1” roll of tape. This makes a nice little table for it. Spray the optic with distilled water and put one or two drops of Ivory liquid at the center. Cut 4 or 5 pieces of the 3”-5” width roll cotton into 3”-5” squares. Spray one cotton square with distilled water and dab the detergent up with it. If the cotton becomes excessively soiled (say half way) use a fresh wetted piece and a small amount of Ivory liquid and continue. NOTE: use the smallest amount of detergent possible; an excessive amount makes it very difficult to remove. Tip the optic to the vertical position and trigger spray it with distilled water several times from top to bottom to remove the detergent. At this point you can use a clean hair dryer to blow the water droplets off the surface and wipe the edge and back dry. This is a quick cleaning that can be used in the field, and even with the optic in the telescope for units larger than 20”. Please note that you cannot clean the edge and back if you elect to clean the optic within the telescope. Use the same procedure for the diagonal mirror.
Part #2. This part of the procedure is for the once or twice a year “super cleaning.” Use the method described in Part #1, but do not blow the moisture off the mirror with the hair dryer. Place the wet optic face-up on the 1” roll of tape. Have 3-4 pieces of the 3”-5” squares of cotton ready. Place a small amount of acetone (danger: acetone is extremely flammable) into the lab nozzle bottle (remember, polyethylene only). Take one of the cotton squares and spray a small amount of acetone on the cotton. Use just enough acetone to slightly dampen the cotton square. Do not soak it! Be sure your hands are CLEAN! Starting at one side of the optic, wipe the optic with the cotton/acetone in straight lines coming towards you. Work your way across the optic. When excessive amounts of water droplets form, discard the cotton/acetone wipe and continue where you left off with a new cotton/acetone wipe. Do not worry about any droplets you may have missed. You will pick them up on your way back across the surface. Continue with the wiping until you reach the opposite side and then work your way back across using fresh cotton/acetone wipes as needed. Be sure only to use one side of the cotton for wiping. Your fingers will leave a small amount of oil on the other side.
Your optics will be “SUPER CLEAN” at this point. If there are any localized streaks on the surface you may huff on the area with your breath and wipe a fresh cotton/acetone wipe. If you work carefully, your optic will not be scratched or sleeked. The most important part of this procedure is stop one. Make absolutely sure that the bevel and edge of the mirror are clean. If you get scratches or sleeks you have dragged dirt onto the surface from the bevel and edge.
This method is SURE FIRE. Enjoy your “SUPERCLEAN” optics.