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Spray Silvering how-to pages are up

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#51 Bob4BVM

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Posted 21 October 2019 - 06:34 PM

It's the cleaning part that I'm curious about. The accelerated life test in the linked article involved dunking the silvered surface into a solution. Does that infer that cleaning might be an option with the overcoat ?

 

If Angel would sell the Anti-tarnish alone and I can clean it, it may be worth investigating. For me, it's not worth doing the whole thing as I can get mirror silvered locally for next to nothing ($35).

 

Steve.

My understanding from the articles is that you won't be cleaning the Ag surface in any normal sense of the phrase as we refer to cleaning Al coated mirrors. Protection & dew/contamination prevention become the big factors in the Ag coating life. 

CS

Bob


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#52 dave brock

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Posted 21 October 2019 - 11:49 PM

For me, it's not worth doing the whole thing as I can get mirror silvered locally for next to nothing ($35).

 

Steve.

Make sure the silvering company knows how to treat the mirror when cleaning/prepping. This is a 16" mirror that I refigured some years ago. It had been silvered by a company in Auckland a few times and "may" have been the cause of the roughness.

 

glenn 16inch foucault a.jpg


Edited by dave brock, 21 October 2019 - 11:52 PM.

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#53 Oregon-raybender

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Posted 22 October 2019 - 09:23 AM

When John Dobson had his mirror silvered at the local shop in SF area. Unknown to him

they buffed it with a power tool and rouge, because it looked under polished to them (IE a few pits on the edge a

common issue with JD first mirrors). So let them know NOT to polish the blank, also you may want to clean it

with chalk first.

 

The project was to help solve the cost of AL coating and shipping of large mirrors. The silver should be covered

when not in use and never cleaned (maybe Distilled water spray) It's not going to the end all and be all solution 

for some folks. At Tinsley back in the 70's we use Peacock, been around a long time, before 70's maybe the

40's or 50's. They supplied the local bath and living room mirror repair shops. A Tinsley we used it just to enhance

the fringes for testing of optics, not for outside viewing. I did coat a several mirrors for myself and friends up to

30". It lasted long enough ( a few months) to make sure the optics worked, later they and I coated with AL.

 

 

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#54 dave brock

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Posted 22 October 2019 - 03:24 PM

Unknown to him
they buffed it with a power tool and rouge, because it looked under polished to them (IE a few pits on the edge a
common issue with JD first mirrors).


In his video, the mirror he makes is also under polished in the outer area. You can see it as it comes out of the coating chamber.

#55 totvos

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Posted 22 October 2019 - 07:55 PM

It's the cleaning part that I'm curious about. The accelerated life test in the linked article involved dunking the silvered surface into a solution. Does that infer that cleaning might be an option with the overcoat ?

 

If Angel would sell the Anti-tarnish alone and I can clean it, it may be worth investigating. For me, it's not worth doing the whole thing as I can get mirror silvered locally for next to nothing ($35).

 

Steve.

I thought it was mentioned in the paper, but just FYI, Angel is merely reselling the anti-tarnish product, in smaller quantities. The industrial source is here:

 

https://www.riogrand...h-shield/335037.

 

Not sure how you would get that into NZ though.



#56 SteveInNZ

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Posted 22 October 2019 - 10:11 PM

It was mentioned either in the article or here but that web page has the statement -

"This item is available for domestic sales only. We apologize for any inconvenience to our international customers."

We get that a lot. :)

 

Steve.



#57 dave brock

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Posted 22 October 2019 - 10:53 PM

Steve.

The Angelgilding site says there is no shipping restrictions on their Angel Guard.

Also says you can pour unused product back into bottle to use again.


Edited by dave brock, 22 October 2019 - 10:56 PM.

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#58 BGRE

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Posted 22 October 2019 - 10:55 PM

NZ post can provide a US shipping address and onship from there.

#59 totvos

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Posted 23 October 2019 - 07:21 AM

We get that a lot. smile.gif

Tell me about it! There is one measly border separating me from them and that is often enough to be a deal breaker. On the plus side, if you were to get it from Rio Grande you would be set for life with a gallon jug. But it is cool that NZ post does the forwarding for you.



#60 JohnH

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Posted 23 October 2019 - 07:39 AM

Make sure the silvering company knows how to treat the mirror when cleaning/prepping. This is a 16" mirror that I refigured some years ago. It had been silvered by a company in Auckland a few times and "may" have been the cause of the roughness.

glenn 16inch foucault a.jpg



Is this Photograph before or after the changes you made? I can clearly see several Zone defects in it and a bit of roughness. This is the look my 12-inch mirror had when I was about eight tenths of the way through polishing, and I started making really good contact between the pitch slap in the mirror, and I adjusted my stroke to make a more consistent contact

#61 MeridianStarGazer

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Posted 23 October 2019 - 11:40 AM

This is fascinating. One thing I wonder about is the smoothness of coating on a micro level. AFAIK aluminum does not add roughness. I have no idea about sprayed silver. Wonder if this has been considered. See discussion around aluminum below.
https://www.cloudyni...the-best/page-2

Joe


That was my first concern. When you say there is less scatter and better color, what are you comparing it to? And older aluminium coating from a not famous coater, or a recent aluminum coating from magestic or spectrum or gso? No doubt a new coat is better than an old one. I wonder how the smoothness of new silver compares to new aluminum, and how fast the silver coats get bad before you realize a new coat is needed.

#62 MeridianStarGazer

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Posted 23 October 2019 - 11:41 AM

A concern I have is how well these handle dust removal. Aluminum with silicon can be gently washed in a sink with soap and water. Can dust and oils be washed off this silver system?

#63 MeridianStarGazer

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Posted 23 October 2019 - 11:45 AM

Have you done a cost/benefit analysis? I'm thinking cost over 10 year period compared to protected aluminum. For example, I paid $300 plus $400 shipping to have a 22.4" mirror coated in 2002, 17 years ago. The coating is still in very good condition. Last year I paid $1200 for coating of the same size mirror, plus around $150 shipping (closer). If it lasts 10 years, which seems reasonable given the performance of the first one, that's $135/year. Factor in the trouble of re-coating each year...

But then I may well try silvering a smaller mirror anyway just for the fun of it and the satisfaction of making the entire mirror including coating myself. So I can see there are other reasons for silvering. And of course coming up with a way to increase its lifetime to 5 - 10 years which also permits cleaning would be a game changer. I agree it is great work. Always fun to explore new frontiers.


$400 to ship a 22.4"? Please tell us more details of the price. That is a lot more than I would have expected. I thought $50 each way.

Are there any coaters in the north west or Midwest with near the price/ quality of Spectrum or Magestic?

#64 dave brock

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Posted 23 October 2019 - 12:13 PM

Is this Photograph before or after the changes you made? 

Before changes. After photo .

 

glenn 16 cass final 012 sm.JPG


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#65 MeridianStarGazer

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Posted 23 October 2019 - 01:41 PM

If this only lasts 18 months, I would resilver every 6 months and see if anyone local wanted to join in. I doubt this would work for a commercial scope seller unless customers were local.

This is a huge gift to any scope owner with a bare or old 18+" mirror, especially 24+". At 30" this is a clear winner.

Edited by stargazer193857, 23 October 2019 - 01:48 PM.

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#66 dave brock

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Posted 23 October 2019 - 05:07 PM

Steve.
The Angelgilding site says there is no shipping restrictions on their Angel Guard.

Got a quote of US$43 to send the smallest bottle ($10.50) to NZ.

Edited by dave brock, 23 October 2019 - 05:12 PM.


#67 BGRE

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Posted 23 October 2019 - 05:27 PM

Try Youshop (NZ Post)

#68 SteveInNZ

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Posted 23 October 2019 - 06:54 PM

Finally found it on their site and ordered a bottle shipped to my YouShop address.

 

Steve.



#69 Bob4BVM

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Posted 23 October 2019 - 09:23 PM

If this only lasts 18 months, I would resilver every 6 months and see if anyone local wanted to join in. I doubt this would work for a commercial scope seller unless customers were local.

This is a huge gift to any scope owner with a bare or old 18+" mirror, especially 24+". At 30" this is a clear winner.

Yeah.

Or as in my case a pair of 17.5's and their secondaries. Complete no-brainer for me, I feel i'd be crazy to not at least try it..

 

I am hoping for a year. Hoping for even more if I can perfect Ed's air system for my b-scope application.  If I can get it to 100% dew prevention (no small feat in my wet climate) I am hoping for even longer life.  With the overcoat film I think this is all about contaminant prevention, including dew. 

 

This is an exciting time for me as an ATMer, very busy with the b-scope project itself, and now this silvering process and Ed's air system integration, all great stuff !  Some days I have a hard time deciding what part of the project to work on next !

smile.gif

Bob


Edited by Bob4BVM, 23 October 2019 - 09:32 PM.

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#70 Augustus

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Posted 23 October 2019 - 09:47 PM

If this only lasts 18 months, I would resilver every 6 months and see if anyone local wanted to join in. I doubt this would work for a commercial scope seller unless customers were local.

This is a huge gift to any scope owner with a bare or old 18+" mirror, especially 24+". At 30" this is a clear winner.

Stop saying "I would" or "I plan to" and actually do something. You have been posting nothing but talk and occasional misinformation for years.


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#71 hbanich

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Posted 24 October 2019 - 12:02 AM

Civility, please.

 

I'm gratified by all the interest and questions about spray silvering in this thread. As some have noted, we don't know everything about this process yet, nor do we have an overcoat that's guaranteed to protect a silver coating to last as long as an aluminum coating. Maybe we'll eventually figure that out and maybe we won't, but we did find Midas Anti-Tarnish and that definitely delays the onset of significant tarnishing.

 

Washing a dirty silver coating is problematic because if will likely remove small areas of the coating that have been contaminated - but in practice we've found that's not the end of the coatings useful life. Maybe one percent of the coating is lost but the remaining 99% is still quite reflective - which we can now verify by measuring it with Rob's PMRT. The coating may look like it has the measles, but as we know, an ugly coating - silver or aluminum can work quite well - that's where the advice "never point a flashlight down the tube of your scope" came from.

 

Still, it's disappointing to see a highly reflective coating that you created yourself go from nearly flawless to obviously flawed within a year, but that's where we're at right now. My hope is that some of you will jump in and give spray silvering a shot, and that your experiences will lead to further improvements in the process.

 

I too am going to modify my scope with Ed's filtered air system with the hopes that it will, along with all the other benefits Ed has demonstrated, will help a silver coating last longer. Perhaps this time next year I'll have an idea how well that's working.

 

To answer stargazer193857's question about scatter and color, the comparisons I've made were between my silvered 28-inch mirror compared to one year old enhanced aluminum coating from OMI on a 25-inch mirror. Using the PMRT, typical reflectivity measurements for a non-tarnished silvered mirror is 99% in the red, 97% in the green and 95% in the blue - about 97% combined. It's not just my opinion the scatter was less and color more apparent, but other observers noticed it too. For instance, for the fourteen years I had an enhanced aluminum coating on my 28-inch mirror I was never able to see any real color in the Ring Nebula. With the silver coating the colors are obvious. For views like that, and many others, I'm more than happy to re-silver every 12 to 18 months.


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#72 LarsMalmgren

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Posted 24 October 2019 - 05:24 AM

Ed's filtering system.

 

Makes me curious lol.gif

Is it described somewhere? Can anyone provide a link?

Google didn't find it for me...



#73 jpcannavo

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Posted 24 October 2019 - 05:58 AM

If this stuff were only cheaper. So I have a 16” planning a 22”. Wondering if the 22 were only used once every new moon how First Contact applied while in storage would extend life. But again, wish this stuff were cheaper. 



#74 Oregon-raybender

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Posted 24 October 2019 - 09:30 AM

The silver does not stick to the optical surface well. Think of as simple lite coating. First contact may remove it.

To be honest, they are exploring a path that may not offer the perfect solution to replace AL / sio2 for larger mirror.

I don't think this was the idea of the project in the beginning. The first step was to find a cheaper way of coating one's 

mirror without costing an arm and leg and not worry about the shipping, do it yourself. This goal was completed. Next

how can we make last longer, weeks, months, may be a year or two? That's were the anti-tarnish came to be. This 

seems to work OK. Remember the idea was to have the coating to last at least for the observing season and get

away from the high cost.

 

I have not seen or read an article on the life of exposed silver for telescopes (or other products), other than the old docs from 1800's. Once AL came to be, that was the perfect solution in most cases and live with it's limits. I think and believe they are totally alone on finding the best mix of solutions to extend the life of the exposed silver. Remember this was

a process to be used a bath/dinner room mirrors, protected by glass on one side and heavy spray paint on the back. So the silver we see is sealed. So issue here is not there is a solution (AL/sio2) but the cost of coating larger mirrors. I can imagine the thoughts of old folks like John Bashear and John Strong would be, chasing this once again.

 

So on less there is someone willing to fund a major project to see this through. It's going to be limited to what time and effort

to the folks who support it. Don't forget, they are limited to what companies can offer to help this. One year we may have a great product, the next not so, because it was not selling well and there was a lack of interest. 

 

Again AL/sio2 was the solution.

 

Starry Nightswaytogo.gif


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#75 brave_ulysses

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Posted 24 October 2019 - 11:22 AM

https://www.cloudyni...or-a-fast-newt/

 

Ed's filtering system.

 

Makes me curious lol.gif

Is it described somewhere? Can anyone provide a link?

Google didn't find it for me...


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