Eyepiece damaged by chemicals

[sheeny]

The attached images are micrographs of the surface of an eyepiece which has been damaged by Aeroguard (or similar) I believe (feel free to correct me or add any other relevant detail Houghy!). The damage is to the coatings on the EP lens. It is evident the chemical(s) have eaten away part of the coating, resulting in glarey haloes around bright objects.

The first two images are at about 50x magnification (the white areas are light reflections within the EP). The remainder are of different sections of the lens surface at about 200x magnification.

The EP is Meade 24mm Series 5000 Ultra Wide Angle EP. Feel free to cry if you like...

Al.

[erick]

Groan! Have to ban all sprays on the observing field - give everyone rollon Aerogard - that's all I carry.

[AdrianF]

Ouch! Considering the cost of these things is it possible to have them cleaned and then recoated? Is it possible?

Adrian

[JethroB76]

I've heard of a corrector plate getting the same treatment, ugh

[erick]

..........and the front objective of an expensive Tak - Quadruple Ouch!

[DavidU]

That looks like some type of film on the lens not MgF etc.
I have read about some fella in the US who tried all kinds of solvents and chemicals who could not get any type of damage to the coating.
I suggest it is a non reflective polymer coating that has been damaged.
If it was me with an expensive eye pc like this I would dis-assemble the Ep and remove the damaged lense.
Then try to find what type of chemical/solvent that damaged the eye p/c and remove the damaged coating from the glass by rubbing a cloth wetted with the "solvent" until all the coating is removed.
What have you to loose? if you can clean up the damaged lens to a clean class state all you loose is one element loosing a coating to one side. Worth a few percent light loss and having a useable Ep again at no cost.
http://www.cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/3236200/page/6/view/collapsed/sb/5/o/all/fpart/1

[GrahamL]

Looks nasty Al , I thought todays coatings were pretty tolerant to solvents , no ones been having a fag at the eyepiece ? Have seen some pics of an eyelens with lots of little burns on it .

[sheeny]

Oh yeah the coatings are tough alright. When Houghy gave me the EP he said "Clean this with whatever you like..." if I can get the surface clear, it's a step in the right direction.

You could be right, David. It may be a film on top of the coating. Still it's a tough film!

There must be some nasty stuff in insect repellents (and I suspect sunscreens) though. A mate of mine used Rid, and still had some on his hands when he picked up his camera. It started to dissolve the the plastic in his camera. It only affected the surface, but his camera has an ugly looking handprint permanently in the surface now.:rolleyes: Finger print ID of ownership!:lol: ...and people happily put this stuff on their skin.:whistle: Just shows how tough our skin is!

Al.

[BerrieK]

Waaaah!!! Yep its nasty stuff alright - no wonder the bugs dont like it.

I did a similar thing to the lenses of some sunglasses not too long ago - except that I had petrol all over my hands (playing with my mower I was) and left some lovely permanant finger prints on the lenses.

Kerrie

[CoombellKid]

Wow! that's nasty!!!

I've used RID for years, never seen anything like that happen. Although
I do walk 20-30m down wind when I spray myself, including my hands.

Used Rid instead is my advice.

Cheers,CS

[casstony]

If it is a film on top of the coating try acetone. Acetone will melt away stuff that isopropyl wont touch.(but be careful to avoid plastic parts)

[Wavytone]

Yep... most include organic solvents for both hydrophobic and hydrophilic chemicals. Diphenylacrylate (dissolves most plastics) is pretty common, and they can include any of the following:
Ethanol
C12-15 Alcohols
Benzoate (Crodamol AB)
Dioctyl Maleate
Ceitol 868
Isopropyl Palmitate
Isopropyl Myristate
Silicone Fluid 345DC
Tridecyl Salicylate (Cosmacol ESI)
Butyloctyl Salicylate
Liquid Paraffin BP
Almond Oil BP
Deodorised Winter Sunflower Oil
Polydecene (Nexbase)
Xylene
Toluene

[Robh]

I'm with Eric, use roll-on Aerogard.
The other problem with sprays, whether it be insecticides, deodorants or air fresheners, is that the chemical cocktail of airborn droplets is going to be breathed into the lungs.

Regards, Rob

[Exfso]

I can confirm that insect repellants totally stuff optical coatings. Last year at Snake Valley someone sprayed repellent near my Tak, and it destroyed the coating to the point I had to send the scope back to Japan. They were initially going to just remove the old coating and re-coat, but apparently the glass was damaged and the objective lenses had to be replaced totally. $6000.00 was the final cost including all the freight. Luckily I had all risks with my Insurance. So as far as I am concerned, any repellents used at least spray types do NOT belong anywhere near sensitive optical coatings.:mad2:

[sheeny]

Just for information, thinners (30% acetone, etc) and acetone free nail polish remover (ethyl acetate and isopropyl alcohol) won't touch it.

In fact careful examination reveals that a tiny section to one side of the lens is not damaged. The bad news is the "islands" that look like a coating on top of the coating are infact the remains of the original optical coating:sadeyes:. It is well and truly etched!

Nasty stuff!

Al.

[GrahamL]

6K to kill a few mozzies .. fair call on the aroguard

I know suncream is nasty stuff I once dropped a dolop on the cars bonnet by the beach by the time I locked up and wiped it off it took a fair swag of paint with it:eyepop:

[pgc hunter]

Just one reason why I never use bug repellant. Personally I can't stand the stuff, both the gross oily feeling on the skin and the smell, plus I end up sneezing like hell should any of that garbage find its way near my nose.

I'd rather suffer hundreds of mozzie bites than use that feral crap they call Aeroguard. Besides mozzie bites are fun to scratch lol

[DavidU]

Good God !!!!!:doh:

[casstony]

Even in southern Australia mosquitoes can carry nasty infectious diseases. I spray RID on my clothing though I might switch to roll-on after reading this thread. I had no idea of the danger to optics.

Combined Ross River/Barmah Forest Virus notifications for last year = 6500. (263 in Victoria). Both diseases have affected my family.

[citivolus]

I got a small amount of sunscreen on the edge of a polycarbonate lens in my glasses a few years back and didn't notice it immediately. The lens cracked in half an hour later while I was wearing the glasses.

[pgc hunter]

Had no idea those tropical diseases are found here :eek: Still, I refuse to use bug repellant. I think the best solution is to just wear long sleeve jumpers and long pants. Melbourne certainly isn't warm at night in summer anyway so discomfort isn't an issue.

[Chris Southby]

RID and aerogard are really corrosive. I was into rock climbing a while back and RID and Aerogard were known to eat through ropes, harnesses and other gear. Imagaine the consequences if it was used and got onto the ropes when your 100m off the ground. Not nice.

[CoombellKid]

And there is that new strain of Dengee Fever (not sure how to spell it,
but sounds similar) which is usually found in the tropics. But this strain
they say isn't effected by the cooler climates of the southern states,
and maybe carried south as far as Melbourne.

pgc hunter, your welcome up here anytime ;) would love to see how
you go with several dozen scotch greys on ya back :thumbsup::thumbsup::thumbsup: they
have nice long needles that can get through several layers of clothing.
I had a mate stay with us once who said the same thing... mozzies
dont effect me... didn't take long before he was pleading for some RID.
But it's those lil black ones with the black and white strip leg, which
are called the asian tiger that mostly carry the bad stuff. Hell where
I'm live, it isn't unusual to have a couple of varieties attacking you at once.

At the end of the day I think I will be more than a lil careful. But
as mentioned ealier I've been using RID for years. Sprayed both sides
of my hands and the residue has never effected my Pentax XW, Naglers,
U/O HD's, Astronomic filters or telescope parts. But I think I'll be washing
my hands before I pick up my 450D.

Another interesting thing is and is why I never buy Meade products. I
had a Meade #140 barlow that had a very similar problem as that shown
in the first post. It appeared a few months after buying it. It was kept
in my ep case with everything else. It really peeved me off, enough to
never want to buy Meade products again thats for sure.

Cheers,CS

[CoombellKid]

Jeeeeez that serious, do you have labels warning you about that on your
climbing gear? I thought climbing ropes of today are mostly made of
synthetics resistant to corrosives.

Cheers,CS

[sheeny]

Ropes aren't resistant to much at all. In rescue training, any contamination other than just water, sunlight soap or lux flakes (pure soap), or dirt is considered grounds to condemn a rope.

There used to be a practice of using insulation tape to mark the middle of a rope. We found a box that someone had made a handle for with a piece of old kernmantle rope and then wrapped insulation tape around it... the rope failed! It had only been lifting a few kilos... the adhesive from the insulation tape had softened the rope over many years. Needless to say, we stopped marking the centre of ropes with tape.

Al.

[CoombellKid]

Al,

When I was working as a rigger, we were never allowed to leave/store
rigging gear including ropes on concrete floors. The lime in the concrete
had a corrosive effect. Probably why you see alot of machine shops
with sealed concrete floors.

Cheers,CS

[Duncan G]

Try flying fox poop, that will disolve ANYTHING.

[Robert9]

Al, I know you're in a better position to see, but looking at your micrographs, I wonder if rather than the surface being etched, the rings are just residue, eg a water soluble salt (not necessarily NaCl) deposit, left after the liquid has evaporated. Have you tried washing gently with a cotton-bud wet with, firstly say plain water? If no success try with a tough of detergent in the water. Failing that I'd Next try ethanol or iso-propanol. Let's face it, you can't do any more damage.
Robert

[sheeny]

No it's not rings of residue... Houghy would've solved that one! It is definitely etched. The formal advice I have got is the EP is not worth repairing (I'm pretty sure Houghy got the same advice). The best remedy may be to simply try to polish the lens surface with optical rouge to remov the coating entirely...

I mainly posted this here so others might become aware of the hazards of usin insect repellents (and sunscreens, etc) around scopes. If it saves someone else from having an EP or scope damaged then it's worthwhile.;)

Al.

[Robert9]

Fair 'nough. Very sad, but certainly something worth learning from.