CR4 - The Engineer's Place for News and Discussion®

Previous in Forum: Glass Fibers for Plastic Compounding   Next in Forum: Dissolving potting epoxy from Hybrid IC
Close

Comments Format:






Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







17 comments
Guru
Popular Science - Cosmology - New Member United States - Member - New Member

Join Date: Apr 2007
Location: 33.49N, 84.19W
Posts: 1492
Good Answers: 3

Resilvering old mirrors?

06/22/2007 11:42 PM

Hi all,

Is anyone familiar with how to resilver an old mirror? I have a couple of very old ones that you can see through in a few places. What's the process for restoring gaps (holes) or can it be done pragmatically?

I realize I could just have new ones made but these have some sentimental value. Mainly I'm just curious as to what the silvering process is, i.e., what steps go into maing a piece of glass into a mirror?

Thaks,

-John

__________________
All worthwhile programmers know that constants always vary.
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
Norway - Member - New Member

Join Date: Mar 2007
Location: Etherville
Posts: 11561
Good Answers: 96
#1

Re: Resilvering old mirrors?

06/23/2007 3:33 PM

I wouldn't restore an heirloom type mirror.Here is one relevant link. As far as I can see , you have to strip the glass of silvering befor applying new. It might be a bit like artexing the Sistine Chapel !

DIY may be risky , but could be fun to experiment with on plain glass.

__________________
For sale- Aardvark. Slightly used, but house trained.. Riding insttructions inc. P&P free..
Register to Reply
Guru
Norway - Member - New Member

Join Date: Mar 2007
Location: Etherville
Posts: 11561
Good Answers: 96
#2
In reply to #1

Re: Resilvering old mirrors?

06/23/2007 3:46 PM

Here is a news flash. (well I had to post it someplace ! )

__________________
For sale- Aardvark. Slightly used, but house trained.. Riding insttructions inc. P&P free..
Register to Reply
Guru
Popular Science - Cosmology - New Member United States - Member - New Member

Join Date: Apr 2007
Location: 33.49N, 84.19W
Posts: 1492
Good Answers: 3
#3
In reply to #1

Re: Resilvering old mirrors?

06/23/2007 4:25 PM

Thanks Kris,

The DIY link looks promising. Just have to locate some kemicals.

These 2 mirrors I have are not heirloom quality just been around a long time and sorta hate to part with them.

Might try the tin foil spot repair technique that Make-Stuff mentions.

__________________
All worthwhile programmers know that constants always vary.
Register to Reply
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3576
Good Answers: 95
#4
In reply to #3

Re: Resilvering old mirrors?

06/23/2007 10:57 PM

I used to resilver mirrors all the time. You can also copper them.

in essence you strip all grease off the mirror. This is a MUST. wash with detergent thoroughly. Then make a low profile tank that is very level and 1-2" deep. Place the mirror in it. rinse with distilled water and then rince with a 1% solution of tin chloride and rinse again, but do not dry.

mix your silvering solution with distilled water and silver nitrate and quickly add your reducer and pour onto the level glass. As you watch the solution will cloud up and get murky and silver will deposit onto the glass. Leave it for a few hours and carefully drain the solution and wash many times with distilled water. Dry and coat with a protective coating. Do a test piece first to see if your cleaning process is good enough. The tin chloride is a silver bonding agent. naked silver soon oxidozes and so must be covered with a special varnish. if you use too active a reduver the silver will flocculate. after use discrad the old solution, do not store it as it wil form silver azide, and blow you up the next time you move the bottle.

I will look up some of my old formulas and put them here when I get home from my two week trip

links here

http://www.google.com/search?hl=en&q=%22silvering+mirrors%22+%2Btin

__________________
Per Ardua Ad Astra
Register to Reply
Commentator
Popular Science - Weaponology - New Member

Join Date: Apr 2007
Posts: 75
#5
In reply to #4

Re: Resilvering old mirrors?

06/24/2007 12:12 AM

Well let's step it up a little how about silvering plastic like polycarbonate?

Register to Reply
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3576
Good Answers: 95
#6
In reply to #5

Re: Resilvering old mirrors?

06/24/2007 7:17 AM

They usually use vacuum deposition of aluminium for plastics like polycarbonate and mylar.

I am not sure if wet process silver would adhere to what is a non wettable surface like plastic.

I know any trace of oil, fingerprint etc on the glass causes an area of non deposition, which is why careful cleansing is de rigeur

__________________
Per Ardua Ad Astra
Register to Reply
Guru
Popular Science - Cosmology - New Member United States - Member - New Member

Join Date: Apr 2007
Location: 33.49N, 84.19W
Posts: 1492
Good Answers: 3
#7
In reply to #6

Re: Resilvering old mirrors?

06/24/2007 2:24 PM

Thanks aurizon,

If possible I would like to repair just the bad spots. There are 3 - 4 places about dime sized, or slightly smaller, that you can see through. Would the technique you mention apply to spot repair?

What do you think about the spot method that make-stuff provides:

"SIMPLE METHOD OF RESILVERING DAMAGED MIRRORS

Pour upon a sheet of tin foil three drams of quicksilver to the square foot of foil. Rub smartly with a piece of buckskin until the foil becomes brilliant. Lay the glass upon a flat table face downward, place the foil upon the damaged portion of the glass, lay a sheet of paper over the foil, and place upon it a block of wood or a piece of marble with a perfectly flat surface, put upon it sufficient weight to press it down tight; let it remain in this position a few hours. The foil will adhere to the glass."

Good idea?

-John

__________________
All worthwhile programmers know that constants always vary.
Register to Reply
Guru
Hobbies - HAM Radio - New Member United Kingdom - Big Ben - New Member Fans of Old Computers - Altair 8800 - New Member Canada - Member - New Member

Join Date: Jun 2006
Location: Toronto
Posts: 3576
Good Answers: 95
#17
In reply to #7

Re: Resilvering old mirrors?

02/18/2008 3:04 PM

This is used on tinfoil. Make sure you get tin foil. Aluminum foil is not tin foil so the mercury will not wet it.

What they are doing is making a tinfoil - mercury surface and when you apply it to the spot on the back it will reflect and partially hide the blemish. For best results trim the blemished area back to a clean reflective surface and then place the foil on the area and ise something to force the mercury flat against the glass.

You could probably try the silvering process on a small area that you lay flat, clean etc.

Practice on a small piece of glass first.

If you need 10 grams of silver nitrate to play with, send me a PM with your address.

Bill

__________________
Per Ardua Ad Astra
Register to Reply
Guru
Popular Science - Cosmology - New Member United States - Member - New Member

Join Date: Apr 2007
Location: 33.49N, 84.19W
Posts: 1492
Good Answers: 3
#11
In reply to #4

Re: Resilvering old mirrors?

06/25/2007 5:19 PM

Hi aurizon,

What's this about using copper? What effect does it give the mirror? Better yet, what makeup does a particular chemical have that makes is best for making a mirror? Are there other materials, such as, for example, chromium, etc?

What makes silver nitrate the chemical of choice? Does it give the best reflectivity or does it bond more easily to the glass substrate than other materials? Is it the most economical chemical for mass mirror production?

Just another thought. Do you know if silver nitrate is still the material used for making very high precision mirrors such as the ones in the Hubble telescope?

Just wondering,

-John

__________________
All worthwhile programmers know that constants always vary.
Register to Reply
Anonymous Poster
#12
In reply to #11

Re: Resilvering old mirrors?

06/26/2007 1:46 AM
Register to Reply
Active Contributor

Join Date: Jun 2007
Posts: 24
#13
In reply to #11

Re: Resilvering old mirrors?

06/28/2007 1:32 AM

Until about 25 years ago which was the last time I was paying attention, Metalic silver or Gold had the highest reflectivity for mirrors. Most modern mirrors are coated with aluminum. I'm guessing the Hubble is silvered? Apparently adding nickel, (Gold?) and I believe mercury can keep it from tarnishing. Of course optical mirrors are "first surface" meaning the light hits the metal and is reflected (not going through glass) which makes the problem of tarnishing greater. Silver nitrate is used because it is easily reduced to metalic silver. This was the one of the first photographic "emulsions", along with silver iodide. Many modern mirrors are vapor coated in a vacuum, by vaporizing the metal of choice which is made into a filament and current passed through it.

Geoffrey Reed

Register to Reply
Anonymous Poster
#14
In reply to #11

Re: Resilvering old mirrors?

06/28/2007 7:01 AM

John, When cleaned the silver adheres quite well and a film builds up from colloidal Ag particles reduced from the Ag ions by the reducing agent. I have not tried other metals, but there may be a number of other metals you can use.

Copper works much the same way to make a copper coloured mirror. Copper mirrors enjoyed a vogue in the late 19th century.

Register to Reply
Guru
Popular Science - Cosmology - New Member United States - Member - New Member

Join Date: Apr 2007
Location: 33.49N, 84.19W
Posts: 1492
Good Answers: 3
#15
In reply to #14

Re: Resilvering old mirrors?

06/28/2007 10:01 AM

Thanks Guest and all. Very good info.

__________________
All worthwhile programmers know that constants always vary.
Register to Reply
Power-User

Join Date: Jun 2007
Location: Port Neches, Texas -- Bond Point
Posts: 117
Good Answers: 2
#8

Re: Resilvering old mirrors?

06/25/2007 8:10 AM

Another method which is not really a repair but may suffice is to remove all of the silver from the mirror. Place a new mirror behind it. For decorative pieces this works well.

__________________
Support your local Shriners, they have provided FREE medical assistance for over 800,000 kids so far.
Register to Reply
Guru
Norway - Member - New Member

Join Date: Mar 2007
Location: Etherville
Posts: 11561
Good Answers: 96
#9
In reply to #8

Re: Resilvering old mirrors?

06/25/2007 8:21 AM

From what I'd read earlier on here , there may be problems if the glass surface is no longer perfectly smooth. I guess it all hangs on the quality that is desired and so on. To illustrate with a joke from a TV show;

Trigger: " I've had this broom for 25 years . "

Del: " What , that's amazing. 25 years ? "

Trigger: " Yeh , and during that time it's had 10 new handles and 30 new heads."

My rendition is not exact , but it conveys the gag.

__________________
For sale- Aardvark. Slightly used, but house trained.. Riding insttructions inc. P&P free..
Register to Reply
Guru
Popular Science - Cosmology - New Member United States - Member - New Member

Join Date: Apr 2007
Location: 33.49N, 84.19W
Posts: 1492
Good Answers: 3
#10
In reply to #8

Re: Resilvering old mirrors?

06/25/2007 5:08 PM

Hi James,

I just might take your advice but I'll probably rearrange it a little; Place a new mirror be///d [in front of] it. Then, mysteriously, the old one might disappear when the wife's not looking.

-John

__________________
All worthwhile programmers know that constants always vary.
Register to Reply
Anonymous Poster
#16

Re: Resilvering old mirrors?

02/18/2008 1:22 PM

My father learned to Resilver Mirrors from his father as a child.

I have yet to get him to share the formula with me, but I do know that it is a long expessive process. First the mirror is stripped in an acid bathand cleaned with a special powdered soap. Then using a moist heated table the chemical mixture is poured onto the glass. After the silver has deposited onto the glass, the rest of the mixture is removed and some kind of copper paint is used to protect the mirror.

This technique leaves you with a much brighter, longer lasting mirror then the common method of spraying silver that is used today.

In listening to my fathers conversations as a child I found that he recommended that a new mirror be purchased unless the mirror was A. an antique B. was engraved or C. had significant sentimental value.

It's been a long time since he has done a table of mirrors, but every now and then he comes across someone who is interested in having them done.

I found this site in error - so I probably will not return My email address is gdjsgirl@yahoo.com

Hope this was helpful!

Register to Reply
Register to Reply 17 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Copy to Clipboard

Users who posted comments:

Anonymous Poster (3); aurizon (3); Dr.Tom (1); GeoffreyReed (1); JasBond (1); Johnjohn (5); Kris (3)

Previous in Forum: Glass Fibers for Plastic Compounding   Next in Forum: Dissolving potting epoxy from Hybrid IC
You might be interested in: Mirror Mounts, Storage Tanks and Process Tanks

Advertisement