Coated Optics - Skyliner 200P Classic Dobsonian

[Charic]

hello.  

Everyone says "don't clean" - "Don't touch" your primary mirror unnecessary, due to how easy it is to scratch or damage the reflective surface/s. Why therefore does the label on my Skyliner 200P classic inform me of "Coated Optics".  Normally a coating  protects or  reduces reflections. Cant find an answer at present?

[NGC 1502]

Most aluminised telescope mirrors are clear silicon overcoated to stop or greatly reduce deterioration of the delicate aluminium. The coating is invisible when you look at the mirror.

The overcoating is harder than the bare aluminium, and if you go carefully and methodically with cleaning, you'll be fine.  

And you don't need perfection when you do clean, just quit when you are ahead.... 

Mirror cleaning guides are very cautious because damage can be done, and also because no one want's to get the blame if you mess things up......

Regards, Ed.

[Charic]

Typical. I search and cannot find my answer. I then post , and find an answer.

Thanks to Harrison telescopes UK. their site informs me that..... 

"Most reflectors today usually have a coat of aluminium as the mirror surface and then an overcoat of silicon monoxide or silicon dioxide to protect it. Silicon dioxide produces a much more durable coat than silicon monoxide but requires specialized equipment to apply it and is therefore more expensive. Protection is needed, because in most reflectors, the mirror is open to the elements and deterioration of the reflective layer reduces the resolution of the telescope. ALL Sky-Watcher reflectors are Multi-Coated with Silicon Dioxide as standard for Optimum Durability and Long Term Performance. "

EDIT: But ED just beat me to the answer. If I had updated the page first?