Strange effect on mirror silvering

[RobertI]

The diagonal on my Heritage 130P is showing a strange effect. When looking at normally as in pic 1 the silvering seems fine but when shining a light from an angle there is a rust coloured mottling on the surface as in pic 2. The scope has performed well on its first couple of outings but wondering what's wrong and if a resilvering might improve performance? 

[Ricochet]

I'm not sure that shows anything other than why shining lights on mirrors is never a good idea. The colour is probably just be due to whatever coating is used to protect the surface. If the mirror looks fine in daylight and performance at night is fine then my guess would be that the mirror is fine. There are a couple of black marks at the top of the mirror I would keep an eye on in case that is something that can spread but where they are at the edge is again probably nothing to worry about. 

[Dave In Vermont]

+1 for not using - or trusting - a flashlight/torch on mirrors. A pristine and perfect mirror will be tranformed into a WWI battlefield. Question: Using just the ambient light of the Sun, or regular home lighting, how does it look?

If it still looks the way that's in the picture - I'd suggest a cleaning. Come back after you've checked it out by natural means, and let us know? In the meantime, here's my favorite cleaning method:

ASO fine optics CLEANING SYSTEM.pdf

Best Wishes -

Dave

[RobertI]

Thanks @Ricochet and @Dave In Vermont for replying and Dave for the link. To answer Dave's question it does look slightly brown at certain angles in normal lighting but nowhere near the same extent. To give a bit more context, I saw this effect during an observing session when I was shining a light to check for dew on the secondary and I was surpised to see it as I have never seen this effect on any of the other mirror scopes I have owned over the years, although I have seen plenty of dirt and dust. I certainly didn't go looking for problems! I guess like everyone I just want to make sure the scope is reaching its full potential. I did a bit more testing (I won't tell you what in case I get told off ) and it does look like there may be something on the mirror, so I think a clean may be in order at some point. another thing I will never get around to......

Anyway thanks for your thoughts