Saintech Enhanced Silver coating trial

Satchmo · #1 24-09-2012, 09:22 AM

I'm doing a trial of the a standard Saintech Quartz overcoat and Enhanced silver in a 12" binocular I am currently modding.

My aim is to see how the two coating perform in different conditions and to be able to compare the coating wear over time.

Last night with a first quarter Moon I noticed that at all magnifications the Moon was clearly slightly brighter in the Silver side.

Tuc 47 Globular showed more outerlying stars popping out and they stayed more constantly in view with the silvered mirror. There was a slightly warmer hue to the view with the silver, and the aluminium looked more `cold'. I definitely preffered the view with the enhanced silver.

A beginning observer would probably not notice the difference but for the more experienced this early result at the eyepiece looks very promising. I tested each mirror with both left and right eye as my left is more sensitive to low light.

alocky (Andrew lockwood) · #2 24-09-2012, 11:00 AM

Hi Mark.
Do you know if the reflectivity of the silver coating has been measured as a function of wavelength? It would be very interesting to compare quantitatively with aluminum.
What's the biggest mirror he can coat?
Cheers,
Andrew.

Satchmo · #3 24-09-2012, 11:22 AM

Quote:

Originally Posted by alocky

Hi Mark.
Do you know if the reflectivity of the silver coating has been measured as a function of wavelength? It would be very interesting to compare quantitatively with aluminum.
What's the biggest mirror he can coat?
Cheers,
Andrew.

Andrew- as far as I know 32" - they need to do some uniformity calibration runs for greater then 18" , and also install a hydraulic lift for larger mirror handling so at this moment 18" but larger won't be too far off. I have emailed Wayne re reflectivity as function of wavelength.

noxidc · #4 24-09-2012, 02:50 PM

Ive bought a second hand 12" gso and have stripped it down already to repaint. the mirror is in terrible condition. my 8" dob had a better image it was that bad. I just emailed saintech and hopefully get a response soon. I was wondering if you knew if there was a difference in coats "expected lifetime"?

gbeal · #5 24-09-2012, 02:53 PM

And I was about to as the same question, life expectancy of both?
My current 10" is eventually going to need a re-coat, although I have put this off for ages. If I can get another ten plus years from a a re-coat then I'll be a happy chappie.
Also, the costs comparison?
Gary

Satchmo · #6 24-09-2012, 03:12 PM

I've been getting 12 years + for simple Quartz overcoatings. As I understand it the silver enhanced type coatings have been in long service at SUSI Stellar interferometer. You would need to talk to Saintech regards warranties on coatings.

MrB (Simon) · #7 24-09-2012, 03:19 PM

Quote:

Originally Posted by gbeal

Also, the costs comparison?
Gary

Mark recently posted a price schedule in the following thread:
http://www.iceinspace.com.au/forum/s...5&postcount=11

gbeal · #8 24-09-2012, 08:17 PM

Thanks Simon.
Gary

Peter Ward · #9 25-09-2012, 10:18 PM

I made an earlier posting re: Sainty cotings which I un-reservedly retract.
( having been up for 36 hours, jet lagged, and not having thought things through )

On discussing the coatings with Wayne this morning, seems I was simply looking at a very rare bird.... multi-layer interference coatings to protect an enhanced silver substrate.

The effect gives the impression of an un-even deposition, which it was not.

My apologies to Wayne Sainty for my not appreciating this was no simple quartz overcoat.

His services are rare in Australia and should be supported.

gasman1 (Gary A Sitton) · #10 01-10-2012, 04:20 AM

Quote:

Originally Posted by alocky

Hi Mark.
Do you know if the reflectivity of the silver coating has been measured as a function of wavelength? It would be very interesting to compare quantitatively with aluminum.
What's the biggest mirror he can coat?
Cheers,
Andrew.

I believe that silver is better at the low end (reds, and infra-red, but that aluminum is better for ultraviolet. I think that fresh silver is a better reflector in the overall visible region, but protective coatings have always been and issue. This will be an interesting test.

Zubenel (Wes) · #11 01-10-2012, 09:36 AM

Hi ,
When I got my 10" F5 mirror originally coated 10 years ago I approach Laserdyne on the Goldy. They offered me a silver coating and Quartz overcoat with standard warranty as a test case for a "New" process that they were attempting to develop at the time. Their technique was to lay a copper substraight down first to combat corrosion. The end result was a beautiful image but alas corrosion set in within 9 months. I contacted them and they agreed to recoat at their expense . So I suspect that unless new techniques have been developed in the ensuing time corrosion will be the biggest issue. Cheers Zubenel.

GrahamL · #12 02-10-2012, 06:13 AM

I don't know anything about the whole process, why does silver
start corroding with an overcoat applied?

Satchmo · #13 02-10-2012, 01:24 PM

Enhanced silver coating on the many celiostat mirrors done by Wayne have been going strong on the SUSI stellar interferometer since 1988.

There is a quartz overcoating over the silver and then a reflection boosting layer .

Quote:

Originally Posted by Zubenel

Hi ,
When I got my 10" F5 mirror originally coated 10 years ago I approach Laserdyne on the Goldy. They offered me a silver coating and Quartz overcoat with standard warranty as a test case for a "New" process that they were attempting to develop at the time. Their technique was to lay a copper substraight down first to combat corrosion. The end result was a beautiful image but alas corrosion set in within 9 months. I contacted them and they agreed to recoat at their expense . So I suspect that unless new techniques have been developed in the ensuing time corrosion will be the biggest issue. Cheers Zubenel.

Zubenel (Wes) · #14 02-10-2012, 03:37 PM

Originally Posted by Satchmo "Enhanced silver coating on the many celiostat mirrors done by Wayne have been going strong on the SUSI stellar interferometer since 1988.There is a quartz overcoating over the silver and then a reflection boosting layer ."
Good to Know.
I would have been exceptionally please if they had used this technique . Needless to say I won't be a repeat customer as they had my mirror for months for the re-coat.

Satchmo · #15 03-10-2012, 07:58 AM

Quote:

Originally Posted by Zubenel

Needless to say I won't be a repeat customer as they had my mirror for months for the re-coat.

I don't like your chances finding anywhere else in Australia to recoat your mirror with an enhanced coating and at an affordable price. Saintech Ion beam Systems manufacture ion beam deposition systems used in Coating plants. They are shifting manufacture of same to USA and I encouraged Wayne to get their 32" capacity research coating plant up and running to coat amateur astronomical optics. We have not had an affordable enhanced coatings available before .

Laserdyne in Qld quoted me $3000 to do an enhanced coating on a 20" mirror in 1999 ! Issac at Chi Qin Co does not offer any service that does not involve the expense and delays of sending mirrors to China, and he never offered Ion assisted deposition enhanced coatings in Australia.

As Saintech continue to invest significant sums of money money in getting their system up to 32" capability I hope the amateur astronomy community will support them and cut them a little slack as they reorganize focus of the business from manufacturing to coating and get to full capacity. We are very lucky to have a couple of PHD graduates to design and implement very effective coatings for the future.

Shiraz (Ray) · #16 03-10-2012, 01:26 PM

Quote:

Originally Posted by Satchmo

As Saintech continue to invest significant sums of money money in getting their system up to 32" capability I hope the amateur astronomy community will support them and cut them a little slack as they reorganize focus of the business from manufacturing to coating and get to full capacity. We are very lucky to have a couple of PHD graduates to design and implement very effective coatings for the future.

couldn't agree more. we are really fortunate to have someone interested in supporting our small community with state of the art capabilities like this. Am considering having my optics recoated as soon as they get fully up to speed, the extra ~10% reflectivity on both surfaces will be a good value for money upgrade.

noxidc · #17 05-10-2012, 12:43 PM

Ill be sending wayne my 12inch mirror in 2 weeks, after considering the 3 types of coats and reading this thread, i decided to go with the silver coating.

Satchmo · #18 05-10-2012, 01:30 PM

Nice one. Let us know how it goes.

gasman1 (Gary A Sitton) · #19 06-10-2012, 03:01 AM

Has anyone checked this coating company this out?

www.evaporatedcoatings.com/mirror-coatings/87-coatings/mirror-coatings/metal-mirror-coatings/108-glass-and-metal-substrates

This is US company and I've sent them an inquiry regarding prices, etc.
They claim 95% visual spectrum reflection for their Aluminum coating.
Apparently, they are using a multiple dielectric overcoat method:

cheville.okstate.edu/photonicslab/labratory_catalog/optics/mirrors/Metallic%20High-Reflection%20Coating.pdf

I wonder if this coating is appropriate for surfaces to high humidity, etc.?
We'll see what the price is, but it's probably too dear for one-off coating.

MrB (Simon) · #20 06-10-2012, 01:21 PM

Quote:

Originally Posted by gasman1

This is US company and I've sent them an inquiry regarding prices, etc.
They claim 95% visual spectrum reflection for their Aluminum coating.
Apparently, they are using a multiple dielectric overcoat method

I think that may be the same as the 'Enhanced Aluminium' coating that is pretty standard from astro coaters.
It is a standard aluminium coating, the dielectrics are likely to be Quartz(SiO2) and Titanium Dioxide(TiO2)