[Chaos-l] lessons on mirrors and cleaning

[E. Allen Davis]

I had my mirror recoated november of 2010 by Galaxy. Pleased with its performance, even though a small defect did develop in the coating not long after I go it back.  

  

But Sunday at Medoc, I noticed some spots all over my mirror.  I have been putting a cloth over it..at the advice of quite a few, but I wondered if possibly something had contaminated the cloth and caused these spots.  I cleaned it hurredly after I got home, and most of those spots disappeared.  However over the last few months, I had been noticing a slow return of the mottled or speckled appearance that caused me to have it recoated.  While cleaning, I noticed from shining a dim flashlight throgh the mirror that there were many many pinholes developing.  I imagine our hot humid summers contribute to this, but still this seemed awfully quick. 

  

But one lesson learned.  I did clean the mirror very hurredly in the tub with tap water and Joy, and because it was so late at night, i propped the mirror up to allow most of the water to drain, intending to clean again the next day with distilled water and Joy etc. 

Numerous spots and water rings were on the mirror the next day, but instead of coming off easily these rings were next to impossilbe to remove.  I used the logic that it was better to get these spots off with tap water temporarily instead of leaving them...in retrospect i should have watied another day and cleaned properly with distilled water and drying the mirror with a blow dryer as usual. 

  

Even acetone, a recommended procedure, would not remove these rings and anomolaies.  In a short period of time, literally 12 hours or so, the coating was damaged by the tap water.  I should have known better, but given what was on the mirror i thought I had nothing to lose.  and really I didn't because the coatings were on the verge of getting like they were before.  



in the end, it is a moot point, because after seeing all the pinholes and change in the coating not related to my tap water cleaning, i had already decided a recoat was in the near future. 

  

My mirror is currently in transit to Florida to a different company for recoating, after taking with someone who advised me and was very informative about coatings and procedures.  Unlike some others, he did NOT recommend putting a cloth on the mirror, not because it would scratch, but because he says the risk is always there that a cloth can attract contaminants and also any dyes etc in a cloth can affect a surface, especially if it gets damp.  i am wondering if some detergent could have been left over in my cloth, since i washed it a while back in the washing machine.  i have decided not to use the cloth after this new coating is applied.  this coating will be a 98% with enhanced overcoat.  Probably similar to what I had, but the owner of this company said that a coating, even under relatively adverse conditions, should last longer than this, and that he had never heard of any of his coatings showing these characteristics. 

  

Anyway, just a little discussion of what's been going on with me this week with my big scope.  i will be using the refractor for the next couple of weeks, weather permitting.  I have always stored my scope in the trailer, because it would be very difficult for me to get in inside the house...and we have no garage or storage shelter.  



sorry for the long post...but it was interesting, albeit frustrating and another expense for me, of which I have had many this year! 



Oh well.  allen 


E. Allen Davis 
 starstorm151 at embarqmail.com 

 "M'Illumino              "I am enlightened 
 D'Immenso"              by the immensity." 

   -Ungaretti               -Ungaretti 

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