A Stupid Stupid thing I did to my 12” Mirror

[Davekyn (David)]

It’s been a while since I did this & it really did not noticeable effect the mirrors performance, in fact it did clean the mirror and give a sharper image. Basically here is the story.

Unfortunately my dobsonian mirror needed cleaning early on after I got it, due to the fact I was not careful about keeping it clean. I took it out in the open on dry windy days where the scope collected a lot of dust inside the tube. I have now also installed a dust cover beneath the primary mirror/over the fan to eliminate the dust the can be drawn from down under.

Anyways...after seeing how much I had neglected my scope and all the dust covering my mirror, I decided to give it a clean and become vigilant thereafter.

Totally impressed with the Lens Pen sold at National Geo...and seeing how I cleaned a filthy pair of Binos back to brand new...guess what I did......

...that’s right...I cleaned my 12” Primary mirror with a Lens Pen...WHAT WAS I THINKING!!!!!!!!!!

I removed the mirror in its cell having no idea what I was doing, except “getting to know my scope” LOL. I sat myself & the mirror at my dining room table directly under the air-conditioning with the fan directed on us, so that any dust or debris that flew in our direction, would not settle on the mirror whilst I cleaned it. I first dusted it down with the brush of the lens Pen & then began to clean the entire surface area as if it were simply an eye piece of Bino Lens.

Initially this method look as if it was doing a great job...as if like new again, however I did begin to notice very faint circular marks which I may as well admit to be very thin scratches...Oh well too late...I kept going and completed the whole mirror. To be honest I believe I could even see very faint scratch marks from the brush!!!!!!!.............I could not believe what I had done & how “FRAGILE” this coating on the mirror was. ANYWAYS...It did look very clean & once I put the mirror back in place & finally collimated the thing again..(mark the position of the mirror as it takes ages to work out the collimation when reassembling) and looked down the tube to see what looked like a new mirror with no imperfections.

Thankfully I could see an improvement & with all the new precautions I now take when exposing my scope to the elements, my mirror still looks new. Unfortunately I know those little tiny wispy marks are there & am hoping that when it comes time...I can have them removed by sending it through the mail to be recoated in say another 18months or so.

I did seem to work much better on my secondary, but still...not a good idea!

Well that’s my story on the stupid/stupid thing I did to my mirror...DONT USE A LENS PEN...but no one else needs telling

[Starkler (Geoff)]

Theres a lot of people who wont put a lens pen anywhere near an eyepiece..... but a mirror?

NEVER EVER EVER rub your mirrors with anything dry!

Theres plenty of online information about how to safely clean mirrors, so I can only agree with you in saying, yes you did a stupid thing

[Octane (Humayun)]

David,

Did you buy an authentic Lenspen, or one of the ones which use the Lenspen trademark, but, are Barska branded?

I've been in touch with the makers of Lenspen, awaiting a reply, but, my impression is that the Barska ones are Chinese clones which I wouldn't touch with a barge pole.

The safest bet is to purchase directly off their web site. Might cost more with postage, but, at least you know you're getting the real deal. Having said that, and, not owning a reflector, I think it makes sense not to use Lenspens on anything as precious as a telescope mirror with coatings.

Regards,
Humayun

[Davekyn (David)]

Yea,
I'm not sure what pen it was, however it did a great job on my Bino Lenses. The reason I did my mirror, was because of what a fantastic job it did do on my Binos......Just checked and yea...it was an authentic Lens Pen. It was not dry to start with, but yea...there was no way in hell enough juice to spread over a 12" mirror & looking back now...I'd never do it again regardless.

I did not research enough was all. In fact I am not sure about Brushing the mirror as some suggest should be done as I swear I could see brush scratch marks? Go figure.

I think I can get the mirror re-coated for around $300.00 plus postage? Any comments on that?

At the moment, I am thankful, that there has been no real noticeable difference in viewing. It seems superficial and hardly worth going to the effort of getting a re-coat at this stage. I am hoping though, that when I do get a re-coat that the service will remove those hair line scratches?

Next time I will follow the instructions via links from this forum.

[Kevnool (Kev)]

Dave if you get a 16 then the coating would be a whole lot more, But then once bitten twice shy.
Cheers Kev.

[RB (Andrew)]

Sorry to hear about your ordeal Dave.

I wouldn't recommend using a lens-pen on a mirror (as you've found out) but on lenses (camera, EP's, bino) they are ideal, I use them with confidence and have never had a problem. Just make sure they are the original "Lens Pen" brand and not a fake copy.

[Stuart78 (Stuart)]

Hi there are you sure it isn't just brushmarks in the grime on the mirror they tend to get like a oxidised film looks like car windscreen after using aircon alot, i would put it in sink of soapy water, it might be ok m8 the coatings on most modern mirrors are not insanly fragile, they have a little durability, i wash my miror in soapy water and if it is really grotty i run cotton bud over surface under water and under the buds own weight no pressure followed by rinse with de mineralised water , it comes up beautiful, i got this technique via this forum, iceman wote up a piece on cleaning mirrors..




Stu..

[Glenhuon (Bill)]

My sympathies mate. We've all made mistakes like that, some even worse, but I won't go into that.

For $300 you're looking at just a plain coating, better to go a few more $$'s and get it hard coated on top. The coating of my 10" cost that, but it was only later I found out that did'nt include the protective coating. With care the uncoated one will probably last 3 - 5 years. Better to go the whole hog and get 10 years+ out of it.

Bill

[Davekyn (David)]

Absolutely Kev, I have not given up on getting a 16" and my oath! I wont be making that mistake again! I agree with Andrew though, that using an authentic Lens Pens is really a very practical solution to cleaning lenses and the like, & that I will not hesitate to use it for such purposes in the future.

Thanks Stuart...by what your saying, It reminds me that I read up on that link...but hearing you say it like that helps me to visualize just how its done...& your comment on oxidization is also worth noting.

I also pay particular atention to Glen as well, because if I remember correctly there are two different procedures to cleaning a mirror that has a protective coating and one that does not have protection.

MMMMMMMMMMMM...do PREMIUM mirrors not only have better properties, but also better protection, because if I continue with this hobby/obsession ... I may very well consider investing in spending more just not for performance, but longgevity as well.

I've ceartainly learn to respect my mirror that's for sure.

[astroron (Ron)]

Dave, I wouldn't be in to much of a hurry to get your mirror re coated, as I am sure with the Hair line scratches that you may have from the brush will not have a detrimental effect on your observing
If you are concerned I would do as has been suggested and give your mirror a wash, using the method recommended on this site, you most probably will see the scratches disappear
Best of luck

[Davekyn (David)]

Thanks Ron...I'll go along with that...Ive pulled off some pretty amazing views since then...It's just a learning experience I guess. When I look down the tube of my scope, I am actually amazed at the clarity and High Def that stares me in the face...other than the fact it's my ugly mug looking back at me...I am really impressed at the resolution and contrast. I love my home theater and bluray technology for is clarity, but I would have to rate the reflections in my Dobs mirror as good as it can get. It's probably just me, but it was the first thing I noticed about reflecting telescopes.

[astroron (Ron)]

At the 41"(1mtr) Schmidt Telescope at Sidings Spring Mountain in NSW they clean the bird crap and dust off with Windex Window cleaner

[jjjnettie (Jeanette)]

Honestly , I wouldn't worry too much about it.

There was an article once showing photos of pro astronomers cleaning one of the big mirrors at Mauna Kea, they use a horse sponge (bought from a produce store) and detergent to wash it clean.
I don't know how much tougher their coatings are but if that's good enough for them it's good enough for me.

[astroron (Ron)]

I hope when you are having a bath Jeanette you use a new one and not the one from Dobbin in the paddock

[Davekyn (David)]

AAAHAHAHAHAHAHAHAHAAAAAAAAAA....... .Sorry Jeanette........Ron has this effect on me. Honestly Ron...

[jjjnettie (Jeanette)]

I sold the Annie Jump Cannon Ron. No more mirrors for me to clean.
Refractors are the go!

[TJD (Trevor)]

AT THE KITT TELESCOPE IN HAWII THEY USE SPEITAIL SAND BLASTERS BUT INSTEAD OF SAND ITS ATOMS REALY I SAW A PRAGRAM ON IT

AND I DID THE SAME BUT I DIDNT SCRATCH MY MIRROR AND......I USE THE IMATATION LENS PEN ON MY 12"BLACK DIAMOND SKYWATCHER DOB
BECAUSE WHEN YOU 13 EVERY DOLLER COUNTS

[TJD (Trevor)]

Originally Posted by TJD

AT THE KITT TELESCOPE IN HAWII THEY USE SPEITAIL SAND BLASTERS BUT INSTEAD OF SAND ITS ATOMS REALY I SAW A PRAGRAM ON IT

AND I DID THE SAME BUT I DIDNT SCRATCH MY MIRROR AND......I USE THE IMATATION LENS PEN ON MY 12"BLACK DIAMOND SKYWATCHER DOB
BECAUSE WHEN YOU 13 EVERY DOLLER COUNTS

NOW I KNOW TO STOP USING IT BECAUSE IT MIGHT SCRATCH THE SURFACE
I LEARN THROUGH OTHERS MISTACKS

[Davekyn (David)]

Hey now, Trev has me thinking about using my water gurney. How about If I flush out my Gurney with spring water and give it a hit with that... ??? ...lol Trev...you make a good point on saving money

[erick (Eric)]

Lenspen - great for fingerprints or eyelash/skin oil on eyepieces. Not great for general crude on mirrors, I would think.