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Roberto
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Back in April, Adam brought up the question of flattening deflected areas of a window.

I thought it would be interesting to show some photos of a project I have just completed involving three, very nice, Renaissance-style windows. All three windows showed severe deflection at the bottom and the top, where the typical stacked horizontal borders, and its lead, hinged. The lead is about 5/32 of an inch, with a very interesting colonial profile and in very good condition. Two other studios had told the Church that the windows had to be completely releaded. I had to argue my case and try to educate the client during several meetings, showing past projects where I flattened windows, and convince them that just because the top and bottom sections of the windows were deflected, that alone was not a reason to completely relead them. Well, as is not always the case, they listened, and at a substantial savings from what the other two studios had quoted them, the windows are flat, the support system has been augmented thus preventing the deflected areas to fail again, and the original lead intact.

I hope the photos are clear and telling.

Looking forward to seeing everyone at the AGG conference next week!
Roberto

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Roberto
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Exterior view of deflection.

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Roberto
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Applying fins to exterior of window.

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Roberto
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Fin at top section.

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Roberto
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Fin at bottom section.

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Roberto
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Close up of the interior of one of the window after attachment of fins to the exterior. Notice how the fins are virtually invisible from the interior.

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Roberto
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Overall after flattening and repair.

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dcs-ny
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we have a similar situation in our studio. Can you recommend a metal source or supplier for the fins that you made.  Thanks.

Roberto
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Doris,
I buy the brass material for the fins from Copper & Brass Sales http://www.copperandbrass.com They are a national company so they might have an office in NY state. They cut the strips from a 4'x8' sheet of .032 HH (half hard) brass, therefore you can get the fins in a variety of widths, depending on the application. I typically get the, 1/2" and 3/4" wide, but have also used 1" wide at times. You have to tin both sides of the fins with solder before attaching them to the window. Also, it's important to keep a wet rag adjacent to the area you are applying the fins to. I always try to bend them as needed before soldering them to the lead.
Good luck

Roberto

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Roberto, I think it would be interesting to know of the earliest situations where fins were used (by you or whomever) and how the windows are faring .  I realize it will take 50 years to truely be a "test", but if it was known where the windows are, someone/we could take photos for prospective clients.  Thanks.

Barbara in Michigan

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Tiffany was doing it 100 years ago. Those windows seem to be fine. There was also an English window I saw once (photo)that had fins in the mid 1800's

 

I get brass "fins" at Manhattan Brass and Copper, 718-381-5300.

They call it brass coil. I get .020 and .032 thickness, from 1/4" -3/4"wide.

Ask for cuttoff coils, or left overs

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Last edited on Sun Nov 16th, 2008 07:33 pm by Vic

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more fins

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more fins

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model railroad track in blue inscription

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Krueger
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Vic, these look to be all from the same window, but at different angles?  Thanks.  Also, were the fins in place of horizontal reinforcing bars, or in addition to.

Barbara

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The original saddle bars were and are in the front of the window. I added horizontal 1/8" thick horizontal brass rebar on the rear of the window directly behind the saddle bars. To the rebar I attach the fins. It makes for a very strong  "continuous" support system.

Yes all the photos are the rear of the same window

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Vic, There have been many Tiffany windows that have sagged badly.  Can we assume no fins were used ?  So was there a certain timeframe when theTiffany firm used fins?...would you know what the time frame might be? 

Barbara

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As far as I know Tiffany used them only on the foiled windows. Foiled windows started to appair around 1901

Roberto
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The earliest application of fins I have seen was on a window I worked on from the Tirolian Glass Masters dated 1860. These fins were attached to the interior of the window rather to the exterior.

As Vic has said, Tiffany used fins on his foiled windows starting 100 years ago and they seem to have withheld time, gravity and ...critics.

Since this topic has been brought up again, I would like to discuss the difference I see in foil windows versus leaded windows. I feel fortunate to have been involved in the repair and restoration of stained glass because, by working on old windows I get to see where they failed, determine how and why, and learn how can I make it better. So the following are accounts from my observation.

I have yet to see a Tiffany window fabricated all in copper foil, with no support bars and only fins to the exterior, suffer deterioration and deflection the way some leaded glass windows have.

There are many of Tiffany’s foiled windows that are wonderful examples. The first to come to mind and probably the best example is the Arlington Street Church in Boston. A Church full of Tiffany windows, probably a dozen, each measuring approximately 4’ wide x 7’ high. Heavily plated, foiled, no support bars to the interior but an amazing web of intelligently and artistically attached fins to the exterior. The windows have never been removed for repair and are in good condition.

A few years ago I worked for a local church where a window from the 1930s, measuring approximately 3’ x 7.5’, was collapsing. The lead was so deteriorated it could be peeled off with my fingernails. The severe deflection was astonishing as there was a support bar every 12 “, yet the window and its lead failed.

Same church, two windows down, same elevation. Two Tiffany windows same dimension as the leaded window. One fabricated in 1905, the second one in 1906. All copper foil, three to four layers, no support bars to the interior, only fins to the exterior. Condition: Flat as a board and as strong as it probably was the day it left the studio in the 1900s.

I recently had in my studio a very large Tiffany landscape window measuring approximately 4’ wide x 8’ high. Once again, all foil, three layers, no support bars, just fins to the exterior side. As flat as it was the day it was installed and just as strong. No deterioration, no deflection. The reason I had it is that the window was removed from its original location in 1967 and donated to a university library where it has been since then. It was being moved into a new location and it had some cracked glass, which was probably caused in the 1967 move. They also needed it safely stored for a short period.

I am not promoting copper foil in our craft. As a matter of fact, I don’t think I would fabricate a window with foil. It just seems so time consuming and I would go absolutely nuts.

But the question is why hasn’t it been accepted? The only argument I hear is that “lead has been used in stained glass windows for centuries whereas copper foil has only been used for 100 years or so”. I would like to hear others' opinions on the subject on this Bulletin Board. Am I alone in my analogy?
Thank you,
Roberto Rosa
Serpentino Stained Glass

Tod
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Roberto:

Is it the case that the (nice, flat) plated, foiled windows also have substantial overlapping of glass pieces; i.e.: one larger piece may cover several smaller ones, thus making that area even stronger than fins (or competent construction) alone may do?

- Tod

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Tod:  The overlapping of plates may also work to strengthen a window.  The combination of the integral fins embedded between the plates is the strongest.  We have added clear, plate glass plates on Tiffany and La Farge windows, combined with fins, to add structural support. 

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Tod,
Yes, strategic placement of larger plates over areas of smaller pieces of glass augments the structure of a window or a particular area of a window.

I think that the benefit of foiled windows is not the copper foil itself, but rather the fact that the entire surface is floated with solder. I have also seen tinned lead in windows, which outlived lead that was not tinned.

We recently restored an 1893 plated window designed Donald MacDonald, leaded not foiled. The majority of the lead was fairly small, 3/16” flat with some smaller leads here and there. Most of the lead showed severe deterioration, lead carbonate etc. (see photo)
Soldered to the deteriorated lead, there was some lead that had been tinned. The tinned lead showed no signs of deterioration, fatigue or anything else. (see same photo)

Many, if not all, of the Tiffany windows I have worked on, have had floated perimeter leads which again remain in excellent condition. As you chisel the putty away, the lead underneath is shiny as the day it was soldered. During restoration, I have always reused the tinned lead and it re-solders beautifully. My friend and fellow craftsman, Dan Maher, once told me that he always floats the perimeter leads on windows he designs and creates.

I’d love to hear if anyone else out there has come across the same thing, and if anyone else has any thoughts on the subject.

Roberto
Serpentino Stained Glass

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Tinned lead.jpg

Last edited on Wed Nov 19th, 2008 08:10 pm by Roberto

elizabeth
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Hello Roberto,

I've been following your posts and have appreciated the depth of sharing and detail of thought. I suppose I have more questions than answers to offer.

Copper foil is really pretty amazing when you think about it, an adhesive clings this thin film of copper to the edge of glass, is completely solderable and becomes the matrix that holds pieces of glass together. Every chip, slight irregularity of cutting, glass variation of thickness is beautifully covered by a bead of solder. It is almost an extension of the glass.

Lead, on the other hand, seems totally clumsy in comparision. A uniform medium, now distictly separate from the glass, requires putty for water proofing and strengthening. Without this glazing process, pieces are loose. Lead does not grasp and hold glass in the same way copper foil does, even with the benefit of re-bars.

You mention the durability of Tiffany windows. My first thought was about the thickness of the copper film, of the copper foil used back then. I know very little about the Tiffany studio, did they make their own foil? Was it pure copper or various hardners included? Just like his glass, did Tiffany have other secrets?

I would venture to say that if two identical panels were made, one with lead the other with copper foil, the copper foil one would be lighter in weight. Could this weight factor also contribute to the longevity of copper foil work and why lead tends to fail ?

My preference too, is to work in lead. And as you point out, it may require a long term committment of time and money. It's tragic flaw and the price you pay for the art.

I am thinking now of cathedral windows and the myth that lead windows need re-leading every hundred years or so, or at least some flattening. It sure would keep us all in some kind of work. However what if it was meant to require routine maintenance? They say the windows in Chartres cathedral hum. It don't know for certain if this is true, however if you think about the huge sails of glass, these windows create, wind, rain and snow would apply a lot of pressure on the glass, as would gravity, once you're up a hundred feet or so. It's essential that the lead can expand and contract, even deform with constant external pressures, and be resiliant enough to hang onto the glass, until it fails. In this regard lead out performs copper foil. And with routine maintenance, these types of failure could be prevented.

Routine maintenace requires man power, expertise, money and a dedicated relationship with glass. In our disposable nature of society, this kind of tending to, is a foreign concept. In an economy that will likely see the closing of some studios, how can long term committments be made with maintenance as part of the service we provide?

This doesn't really address why Tiffany's windows are in as good a shape, as they are. They are much smaller than cathedral windows and as Tod points out, have plating for added strength. Could one argue that the chemistry of opalescent glass is more durable than european antique? I certainly have come across glass that has difficult to cut, of both sorts. Likely an annealing issue. Did Tiffany and his glass makers have a few other secrets about the very making of the glass? There are so many possibilities for exploration. Like I said, more questions than answers.

This has been an excellent excercise and I hope others jump in.
elizabeth

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This link will get you to the real inventor of the copper foil method

http://www.google.com/patents?id=jUVbAAAAEBAJ&printsec=abstract&zoom=4&dq=copper+foil&as_drrb_ap=b&as_minm_ap=1&as_miny_ap=1840&as_maxm_ap=1&as_maxy_ap=1901&as_drrb_is=b&as_minm_is=1&as_miny_is=1840&as_maxm_is=1&as_maxy_is=1901&num=100#PPA2,M1

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Vic wrote: This link will get you to the real inventor of the copper foil method

http://www.google.com/patents?id=jUVbAAAAEBAJ&printsec=abstract&zoom=4&dq=copper+foil&as_
drrb_ap=b&as_minm_ap=1&as_miny_ap=1840&as_maxm_ap=1&as_maxy_ap=1901&as_drrb_is=b&as_minm_is=1&as_miny_is=1840&as_maxm_is=1&as_maxy_is=1901&num=100#PPA2,M1


Absolutely fantastic! Thanks, Vic. And thanks, Roberto, for your thoughts. Certainly we have all seen the terrible condition of lead in the rabbet compared to the solder joints there. Dan's idea would seem to have merit. But, I suppose this is not something a restorer should "add" to a window?

Historical sidebar:

I, and others here, I'm sure, started sg work before adhesive-backed foil was available. When I decided to try foil, I bought a roll of 6" wide copper sheet (.001" thick) x who-knows-how-long from Admiral Brass & Copper, I suppose. I still have some of that. The purchase was made in the late 1960's. Mostly, I tinned pieces as I foiled, no adhesive at all.

Early in the '70's, some clever soul began using 1/4" foil swiped from the custom slotcar hobby field. This foil had horrible adhesive which oozed out when heated, had to be trimmed with a blade and often pulled completely free of the foil! Retailers asserted that the purpose of the adhesive was mostly to keep the foil on the glass until you could solder it. Salesmen will tell you anything, eh?

- Tod

Last edited on Fri Nov 21st, 2008 02:17 am by Rebecca

Roy
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Dear Elizabeth,

 

You mention "Myth"  and in one of your statements " the longevity of copper foil work"   Is there evidence that copper foil outlasts leaded windows?

 

A couple of things that worry me about copper foil windows are, how long does it take for the adhesive to deteriorate and how do you make the windows waterproof without having external glazing, especially in the case of stone mullioned  church windows? 

 

If there is no external glazing the stained glass held by inflexible copper foil will crack and leak due to the  weather,  another problem is,  in UK architects would not normally recommend sheets of glass on the outside of their Gothic church windows because of the reflection from the sun, the alternative, such as polycarbonate is even worst as it deteriorates after a comparatively short period.

 

Best wishes,

 

Roy

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Thanks for the link Vic, very interesting. I thought I would weigh in on a
few things. Roberto, I tin my outside leads to resist corrosion caused by
the environment of wood frames. Organic acids from the wood, possible
growth
of nasty little critters that might also cause oxidation. As you mentioned,
and I think most of us have noted the perfect condition of the soldered
joints of perimeter leads and the rest of the lead severly deteriorated.
Most of the Tiffany and LaFarge windows I have restored had tinned leads
and
I noted the perimeter leads being in better condition. It seemed like a
good
idea to tin the perimeter leads so I do it on all restoration projects. In
my new work I tin all the leads. Again, Tiffany and LaFarge seemed to think
it was a good idea so I do it. I think it strengthens the lead and I get a
nice even patina. It takes a few extra minutes but I think it is worth it.
I
have also noted on cabinet doors oxidation on the leads on the inside
surface. I think this is probably caused by the wood. So again I do cabinet
doors in copper foil, or tin all the leads.
Catherine and Roberto and copper foil, I have also noted the good
condition of copper foil windows. Seemingly they are weakest when there is
a
big window with big pieces involved. Maybe the expansion and contraction
stresses a few key joints. But in windows of high complexity they are
usually in good shape. In leaded windows of high complexity there is
usually
buckling. I always say buckling occurs because it can. Leads that create
general patterns or lines across windows make "hinges" where the lead can
distort. Of course horizontals are the weakest followed by diagonals and
circles and sometimes a series of diagonal corner frame patterns act like
circles and distort. How support bars work in concert with the leads is
another discussion.
I agree with previous mentions about foil windows being lighter and the
soldered foil lines are much stiffer than lead. When leaded windows are new
and the waterproofing is strong the glass in the leads has a harder time
pushing out of plane. Design lines that wave back and forth also make
buckling more difficult than with straight lines. But as the waterproofing
loosens and the forces of expansion and contraction occur the buckling
happens in leaded windows. In copper foil windows any wave or wiggle in the
design line reduces the opportunity to hinge and reduces the buckling. The
foil and sloder conform right to the edge of the glass so even tiny shapes
that corrugate the line make it much stronger. I use both copper foil and
lead in my new work and sometimes mix the two together to get different
line
effects. Like a good drawing I think the variety of lead and copper foil
lines make for a tasty image. Dan Daniel Maher Stained Glass
http://www.dmstainedglass.com


Posted for Daniel Maher by Rebecca

dcs-ny
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a belated thank you for your fin supplier recommendation .. and to Vic for his...

style="BACKGROUND-COLOR: #ccccff"the subsequent dialogue about using fins in windows has been most interesting and informative too by others.

style="BACKGROUND-COLOR: #ccccff"The window in our studio is 6'w x 10'h,..had multiple horizontal support bars (interior) throughout, as well as fins in numerous locations  (exterior) .  Also there were many small round support bars around medallions... at  the top of the arched panel.... and the entire window failed... almost 80%of the wire ties separated, and the window started to accordion collapse on itself.  The only temporary saving grace was plexiglass that was installed on the outside and inside sometime in the 1990's  ( per the owner).

style="BACKGROUND-COLOR: #ccccff"everyone's commentary is much appreciated.


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