Eta Carina with junk yard dob

[doppler]

This old 10" meade starfinder was salvaged from the tip/recycle centre for $50 with a badly corroded primary mirror. After a acid wash and a home re-silver the primary is seeing light again. A fair bit of coma but it is a F4.5. 23 X 20sec @ iso 3200 mounted on eq pier with RA drive only

Rick

[DavidU]

Excellent result. Great scope story as well !

[cometcatcher]

Awesome! You HAVE to show me how to do resilvering one day.

[doppler]

The proccess is fairly simple and a fun chemical reaction, the hard part is getting good quality chemicals. The best part it cost about $15 to silver a 10" mirror. The mirror is good for over six months before it starts to tarnish and turn yellow.

[raymo]

Good image Rick. Incidentally, I wonder whether Tarnoff would take off the tarnish without destroying the silver.
raymo

[doppler]

The coating does not bond strongly enough and would rub off if polished. Apparently there is a chemical that can be used to condition the glass to create a stong bond but I have been unable to source this in Aust by mail order. It is readily available os but I am unsure about customs regulations with importing chemicals. Here is a short clip showing the chemical silvering proccess that I have adapted to coat my mirror.
https://www.youtube.com/watch?v=6vduHWV47Dg

And some pics of the ugly dobling

[raymo]

The reason I asked about Tarnoff is that you don't have to touch
anything. Just immerse any silver or silver plated item into it, and
it is instantly sparkling. I have a silver sailing ship model which I dunk annually. Instantly looks like new. Just rinse under a tap afterwards, and leave to dry. Might be worth a try when you deem the mirror to need resilvering.
raymo.

[doppler]

Thanks Raymo, I'll check it out. If I could get some nitric acid I would be able to recycle the silver coating and it would cost virtually nothing to resilver the mirror. The two chemicals I can't get are nitric acid and amonium (nitrate or concentrated liquid) in non comercial quantities. Apparently they are bomb making ingredients. I have been able to improvise but maybe the impure chemicals are affecting the process. But for the moment it's working and has not cost much to ressurect the scope.

[cometcatcher]

As a coin collector, we know that Tarnoff eats metal. Only micro amounts, but that is all a mirror coating would be.

[raymo]

It was only a thought. He has nothing to lose if the mirror needs resilvering anyway.
raymo