My eyepiece is no longer 'cooked'!
After some two weeks of work I have a working Meade 18mm UWA eyepiece again!
Remembering that this eyepiece was totally unusable, I didn't have anything to lose when deciding what remedies to use in trying to remove the damaged lens coating.
My first attempts were with acetone, in the form of my grand daughters contaminated nail polish remover, bright red!
This did indeed remove a great deal of the burnt brown residue of the lens coating. I managed to give the lens two or three acetone baths each day. The acetone evapourated/dried with a red residue of nail polish contaminant which, if left overnight, seemed to gradually remove more of the damage. Clean cotton buds were used for each application.
After a few days however the acetone didn't seem to be making things any better.
So I tried WD40, a suggestion from Cloudy Nights members, but I couldn't really see any improvement.
The eyepiece was still unusable, with only a small central region apparantly clear of damage.
Next step, paint stripper, and it works! The only ingredient mentioned on the tin is Methylene Chloride.
Several applications each day for a week, allowing the paint stripper to dry to a thin crust, removing the crust and carefully polishing with an optomotrists lens cleaning cloth plus lens cleaner.
The paint stripper has removed 95~98% of the damage, with just a thin 'cloud' remaining at the extreme edge of the field of view.
I'm sure another week of the paint stripper treatment will complete the process, but the weather is finally clearing up so I'm going to do some star gazing! Hopefully the good weather lasts for Border Star Gaze!
I've re-blackened the lens edge with a Sharpie permanent black marker, put it all back together and the views are excellent!
As you can imagine, I am one very relieved star gazer!