Cleaning optics

Without having tested this by myself, I would try following approach:
1. Step use a micro fibre cloth and make it wet (not dripping wet) with a solution of common dishwashing detergent (but the pure ones, i.e. unscented etc.etc.) in distilled water to remove most of the grease. Repeat this until the rough stuff is gone. Take care to not use too much of liquid as it might get into the tiny edges and stay there. Less is more.
2. Then use the other common optical cleaning procedures (alcohol based solutions and micro fiber cloths or dedicated optical cleaning liquids). 

That's what I'd try. Of course, no guarantees 

CS!
Björn

I personally bought cotton fibre cloth and isopropanol (Amazon), works well when you need to go a step further to remove grease.

Read these instructions from Astronomik website :
https://www.astronomik.com/en/accessoires/optikreinigung.html

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Use the paint brush and wipe of the dust from both sides of the filter. -Done and ready!
When your using a Microfibre cloth apply soft presure and wipe fingerprints of in streaks across the surface. (It´s a good idea to mark one side of the cloth. Use allways the same side for the fingers and the other for the optical surface.) After several cleaning processes you will have to clean the microfibre cloth in your washing machine to remove the grease form the fibers. If you still can see traces of grease on the surface after the cleaning process with a microfibre cloth you will need Isopropanol and a special cotton-fibre cloth for optical cleaning.
Suck a part of the cloth in Isopropanol and wipe the grease away.

You may buy Isopropanol at your local pharmacy. Please choose the best purity grade. A small bottle of 100ml will last forever. We cannot ship Isopropanol due to legal restrictions. But you may order all other stuff mentioned here.
 Important advice when using Isopropanol:
Isopropanol is a transparent, colorless, very votal and flammable liquid. The stench will bring in mind a hospital or medical office. Isopropanol is used for desinfection purpose there. Isopropanol and air are mixing up to very flamable vapors. These vapors are also deafening. Please make shure that your working place is well vented!
Contact to the eyes or mucosa causes irritations. 
When buying a bottle of Isopropanol in your pharmacy you will usually get a safety data sheet. (At least in germany). Please follow all instructions given there!
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If using Isoprop I would dilute the isoprop 3 to 1 with  water to begin with and apply with a lint free cloth. Do not touch the surface of the cloth that touches the optics with your fingers and degrease them beforehand anyway. Do this a few times with fresh cloths and inspect in sunlight. Then wipe any isoprop smears away with a fresh cloth and  water. Finally wipe with a micro fibre cloth possibly breathing on the glass beforehand if necessary. Pec Pads are lint free. If you have triple distilled water so much the better.

1) Neither isopropyl alcohol or acetone will damage optical coatings.  If a surface is really dirty, mix a batch of 99% isopropyl with distilled water in a spray bottle.  Spray the surface and dab it clean with Kleenex brand tissue (just tissue without anything added to it.)  Once you have most of the dirt off, then lightly spray the surface and wipe it clean with the tissue.  If you are careful, you won't leave any scratches and the surface will look as good as it did when it came out of the coating chamber.  Neither isopropyl or acetone are likely to remove silicon grease.

2) I've used Naptha to remove soft, uncured silicon adhesive (or sealant) on acrylic and it may work well to remove to remove silicon grease.  Wear glove and do the work in a well ventilated area.   I haven't researched how Naptha might affect an optical coating but if you only need to clean a small region, clean off the silicon and then quickly spray it down with the alcohol mixture to rinse off the Naptha and polish the surface.   Most hardware stores (including Home Depot) carry Naptha.

John


IMPORTANT NOTE:  I totally screwed up in my earlier post and mentioned MEK when I meant to say "Naptha".   MEK actually might work but I wouldn't try it.  Naptha is safer in almost every way and I apologize for the goof!

Naptha will certainly solve the silicone grease but as John said, who knows about the coatings.

Maybe I should also add this as a general comment: optics only need rare cleaning if ever! Of course if you have accidents like Patrick, you'll have to clean it. Also if you have fingerprints or pollen on the optics. This can do harm to the coatings and glas. Everything else doesn't do anything. Some dust on optics doesn't deteriorate optical performance. Maybe if you have a scope which is exposed to the elements 24/7, cleaning might be indicated from time to time (I'm talking about months to years). If you're always covering your optics after use, there's hardly any need to do cleaning.

Thanks, John.   I really appreciate the response.  Fortunately, I've stayed away from Windex and it's similar competitors.  I'll give the alcohol, along with lint free clothes and post the results back here for others who had similar accidents with their optics.

CS to all

Pat