How to silver a mirror ?

[steamingbill]

I've been googling and reading about telescopes for the last week or so ever since I bought a little Aldi National Geographic telescope that clearly showed the craters on the moon. Amazing.


I thought a 6" or 8" telescope would cost a fortune so started reading about diy telescopes and this led to mirror grinding - seems interesting, and I usually see a line that goes something like this .........................


".............. after you have ground the mirror its quite cheap to get it silvered by your local mirror silvering place ..................."


Maybe I'm not googling the right terms , I get sites that look to be specialising in expensive custom optical jobs for industrial applications and scientific laboratories.

Has the local cheap corner shop mirror silvering place disappeared just like the local foundry has ?


Anybody here ever done this ? Once all diy costs are considered, especially silvering + protective coat, is it cheaper and quicker - but far less interesting - to buy mirrors ?


Bill

[Bohdan]

I used to have a factory next door that silvered coffin handles that he made out of sheet metal offcuts. He would silver them and then coat them with lacquer to stop the silver being rubbed off.

The process was home made and very simple. He had two spray guns taped together so that the chemicals that he sprayed mixed as they hit the item to be silvered. A similar, but more sophisticated, process was used to silver the acetate masters that were then electroplated to manufacture vinyl records.

One of the chemicals used was silver nitrate and I can't remember the other but you should be able to find out via google.

If you can get the chemicals just try pouring them together on the glass.

[steamingbill]

Page 51 of this book Brashears Process

https://ia600808.us.archive.org/27/items/ConstructingAnAstronomicalTelescope/Matthewson-ConstructingAnAstronomicalTelescope.pdf

And then googling Brashears Process opens the door to other stuff ..............

This lot will send you a price and do it for you if you contact them ........ Products (http://www.saintech.com/index.html)

and I finally ended up here - which seems to be very good and exactly how to do it yourself

SILVERING A TELESCOPE MIRROR AT HOME


(http://www.webstertelescopes.com/silvering.htm)

Bill

[ian]

Haven't read Bill's links, but I understand that in the old days "silvering" included coating with mercury, while more recently "silvering" includes aluminium coatings

[rrich]

You said that you've found businesses that do major optical tasks.

I would do a simple inquiry asking if they will do the silvering job for you or if they don't do small jobs the should be happy to refer you to a shop that will do the work. Most companies consider it an honor to be asked for advice and are only too happy to refer you to another that can accomplish the task.

[steamingbill]

You said that you've found businesses that do major optical tasks.

I would do a simple inquiry asking if they will do the silvering job for you or if they don't do small jobs the should be happy to refer you to a shop that will do the work. Most companies consider it an honor to be asked for advice and are only too happy to refer you to another that can accomplish the task.

Thanks Rrich,

I have found out that the high -tech type companies will silver a 6" mirror for between $100 and $300 and I need to add postage to and from their workshop

I found a more "domestic" company in Sydney that resurfaces household mirrors will do the same job for $50 and this doesnt include the protective coat that is included in the high tech quotes.

Am still investigating feasibility of making a telescope vs buying one. Am starting to think the economics is only favourable if the silvering is not farmed out.

.............. and being as you can get 6" to 12" telecopes for $50 to $1100 it strikes me that I'd only make one because I want to learn how to make one rather than save money (and maybe end up with a dodgy first try - will do better next time ?).

Here is an example of current prices of imported telescopes Browse All Types of Optical Telescopes and Telescopes Accessories at Australia's #1 Store (http://www.andrewscom.com.au/optical-telescopes)

Bill

[q9]

If you have a look on Project Gutenberg and dig through...photography, there is a really old book that describes how to grind your own lenses. So I think no need to stop at just making your own mirrors.

But why can't you just, like, buy a regular mirror and make it the size/shape you need?

[steamingbill]

If you have a look on Project Gutenberg and dig through...photography, there is a really old book that describes how to grind your own lenses. So I think no need to stop at just making your own mirrors.

But why can't you just, like, buy a regular mirror and make it the size/shape you need?

Thanks for the tip about books in Gutenberg - haven't had a look in there for a while now.

I don't think you could buy a flat mirror and reshape it into a 3d spherical or paraboloid shape which is what a telescope requires - this thread started off with me wondering about availability of silvering services for people who do diy grinding of parabolic and spherical shapes in thick glass - eventually found some silvering companies and got some indicative prices. I was also wondering about some of those magnifying bathroom shaving mirrors - probably not suitable or others would have used them and written about it by now, but truth is I simply dont know enough about making mirrors and telescopes, am learning.

These forums have threads about diy telescope making - iceinspace and stargazers lounge. WIll go and pester those people for a while.

Bill

[ian]

Thanks Rrich,

I have found out that the high -tech type companies will silver a 6" mirror for between $100 and $300 and I need to add postage to and from their workshop

I found a more "domestic" company in Sydney that resurfaces household mirrors will do the same job for $50 and this doesnt include the protective coat that is included in the high tech quotes.
Hi Bill

when I was a teenager, my dad and I built our own 6" or 8" Newtonian telescope. I can't recall which.
I don't recall if we bought or ground the mirror. But I do remember that we had to get it silvered, and that the silvering had to be absolutely consistent across the mirror's surface or the reflected light would not focus at a single point.

With a household mirror it doesn't matter if the thickness of the "silver" is inconsistent. With an astronomical scope, consistent thickness is critical.

[AlexS]

Thinking laterally about the mirror ... assuming you find somewhere to silver the surface, rather than grinding a glass mirror, could you make one from, say, epoxy, by rotating a flat container on a turntable while the mixture sets? The surface will form a parobola. You might have to tweak the rotation speed to get the right focal length, and it may need a final polishing before silvering, but could be worth a try.

[steamingbill]

Thinking laterally about the mirror ... assuming you find somewhere to silver the surface, rather than grinding a glass mirror, could you make one from, say, epoxy, by rotating a flat container on a turntable while the mixture sets? The surface will form a parobola. You might have to tweak the rotation speed to get the right focal length, and it may need a final polishing before silvering, but could be worth a try.

Wow - didnt know that. Wonder if the mirror making gurus know that trick.

Bill

[Chief Tiff]

Don't they make high powered astronomy mirrors like this by rotating a big drum of mercury to form a parabolic surface?

[AlexS]

The surface will form a parobola.It might even form a parabola.:rolleyes: Sorry.

[steamingbill]

Did some googling "mirror spin parabola" and this yielded heaps of videos on youtube.

I have gotta get into the current century and start looking upon youtube as a useful resource instead of just a curiousity.

https://www.youtube.com/watch?v=cBWU7dEImTw - and then there is heaps more videos in the side panel on similar themes.

Bill

[HiString]

Have a look at our Aust., astronomy forum IceInSpace (http://www.iceinspace.com.au/forum/) ......there's a number of guys who have made their own mirrors.