Whats this on my mirror

[davidpretorius]

Ok, have been leaving my scope out heaps over the last few months. We have no nuclear power plants or acid factory, but something is on my mirror and won't come off.

I have washed in detergent, sprayed with windex, rub softly and then hard with cotton buds, rubbed hard with a cloth and even rubbed my finger across the surface.

These marks are not on the surface, more part of it i reckon.

Do i need a recoat???

[asimov]

What the HELL!!??? That looks positively nasty Dave!

Do you live on/near the coast?

[matt]

:scared:

You sure you wanna be doing that Davo?

If those marks aren't part of the surface, you might be adding to your woes???

I had similar "blotches" on my mirror but found the Bintel "snake oil" UHTC cleaning fluid quite helpful.

[asimov]

Stand the mirror up vertically in a dark room, & shine a torch on the BACK of the mirror & see if you can see light coming thru on the aluminized side...

[davidpretorius]

thanks guys, it looks pretty bad, but will check tonight in the dark.

i only touched the surface whilst under fast running water to see if it was stuck to the surface or part of the surface coming away

[asimov]

A reaction to pollen off a certain kind of tree perhaps?? Seasalt will etch the hell out of coatings too from what I understand.

[asimov]

Face on piccy would be good davo! In focus please. Only if you have time of course..

[ballaratdragons]

Davo,

I have never seen damage in that form before!

My old scope had 'craze' but craze looks nothing like that!!!! Craze is when the air gets under the protective over-coating through a microscopic hole or scratch, and is easily recognisable because it looks like tiny wiggly lines.

Are you able to determine whether the marks are ON the surface or UNDER the surface?

[davidpretorius]

not sure ken,

i am going to try asimov's torch up its bum tonight to see if the coating is being eaten away.

initially it looks like rain has got on and left marks, right up until you can't wash / rub / kick it off with you boot stage

[asimov]

Hmmm, I've never seen this before,thought I'd seen it all with coating problems/etched coatings/stains/etc.....this is a new one on me!!

The last time I had to re-aluminize a mirror was back in the early 80's after sea air stuffed the coating after 7 years.

[mick pinner]

everything you have used is water based, try isopropyl alcohol.

[matt]

Yep. Isopropyl alcohol is a key component of the Bintel snake oil:D

[davidpretorius]

ok. mirror coming out again and isopropyl it is.

thanks mick.

[[1ponders]]

Any Eucalypts in the area Dave?

[spacezebra]

Hi there

Yes I agree 1ponders - I left the recycle bin under our New Zealand christmas tree and I dont know if it occurs only at this time of year - but I found that the bin had all these small droplets of sap? Was a pain to clean. Where have you placed your scope?

I would not recommend the cleaning method that I undertook - for your mirror, try the snake oil.

When not in use I use a cover - dont want to risk an inquistive bird leaving deposits. Hope all goes well.

Cheers Petra

[acropolite]

Dave, my guess is that it's from woodfire smoke and fog combined, I don't leave my scope out any longer than necessary because of the smoke. My boat paint deteriorated worse in Lonny over winter than when left at the coast.:confuse3:

[davidpretorius]

i may sue the council for a 16" replacement.

i think you are right Phil

[ving]

gee dave, thats awfull!!!
hope you can get it off :(

[EzyStyles]

hi dave,
sorry to hear about your mirror :( :( i was wondering do you notice any difference now when imaging?

[davidpretorius]

thanks guys,

ezy, no difference in imaging at all

[matt]

No diff?

Goes to show

[astro_nutt]

Hi dave, sorry to hear about your mirror...but it looks like salt oxidization on the aluminium coating...the same would happen if you owned a motorbike with an aluminium muffler...the road salt would do the same...

[Starkler]

If you decide that you cant stand the blotches, it sounds like a good excuse to send it to Mr Suchting for a nice refigure and recoat ;)

[davidpretorius]

aluminium tube next, and then a review of a bigger mirror or recoat this one.

must be in place for jupiter opposition next year

[Starkler]

I wonder if Birds old mirror and OTA are for sale :whistle:

[jjjnettie]

I've got similar marks on my mirror!! Not as bad as yours though.
Definately corrosion on the surface. I put mine down to the frog that was using my mirror as a toilet.