Secondary Mirror has indigo colour swirls

[m11]

Hi All,

I tried to clean my secondary mirror with isopropyl alcohol which investigating further is the probably the wrong stuff to use.

Would like to ask for advice regarding my dobsonian secondary mirror in that I have noticed indigo swirls on it? Have I killed the coating and is it worth getting it recoated? Is the recoating not worth it and I am better off getting a new secondary mirror?

Thanks,

M11

[iborg]

Hi

My guess is that it was not pure isopropanol and that there is an oily residue left behind.

I would also guess that it can be cleaned, either with pure isopropanol or a good quality lens cleaner solution.

Philip

[m11]

Secondary mirror pic.

[m11]

Hi Phillip,

Thanks for the reply. Is there a lens cleaner solution you would recommend?

I guess I am worried I might I have killed the coating?

Thanks,

Melvin

[glend]

Its probably fine. I stay away from isopropyl because it can leave evaporation gradients behind. Modern mirrors have hard coating and are certainly not soluble in the way you suggest. I bit of soapy water and a rinse with distilled water will usually do a fine job.

I use Bintel's UHC ckeaning fluid fir just about everything.

[m11]

Hi Glen,

Thanks for that. I was really worried I really stuffed up and killed the secondary.

Will definitely just use soapy water for next time. Is dishwashing detergent ok or do I need a particular brand? Will look up the Bintel cleaning fluid.

Thanks,

m11

[glend]

Mild dish detergent is fine. There are plenty of mirror washing videos online. Don't forget to rinse with distilled or demineralised water to avoid spots.

[m11]

Hi Glen,

Thanks for that. Will give it a go tomorrow. Much appreciated.

Regards,

M11

[m11]

Thanks everyone, i was to clean pretty much the whole secondary mirror with detergent and demineralised water.

My sincere thanks,

M11