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About Vic Rothman
Expertise
I can answer questions concerning design,fabrication, repair, restoration,and instillation of stained glass windows. I know about the history and technique of stained glass. Former member of the restoration committee of The Stained Glass Association of America.

Experience
I have over 36 years experience in the stained glass field. I have done craft shows, managed a stained glass retail store, taught classes, was a studio foreman and have had my own studio for over 16 years.Former restoration committee member of the Stained Glass Association of America. Founding member of The American Glass Guild.

Organizations
Stained Glass Association of America
The British Society of Master Glass Painters
New York Landmarks Conservancy
Association for Preservation Technology International
American Institute foe Conservation of Historic & Artistic Works
American Glass Guild

You are here: Experts > Hobbies > Stained Glass > Stained Glass > rebar question

Stained Glass - rebar question

Expert: Vic Rothman - 10/26/2009

Question
Do I solder the rebar on my panel (which is very large 20x80), before or after I cement it? And... do you like miracle mud? Also, the rebar goes on horizontally right? Or, both since this is so large? Thanks so much!

Answer
1-You putty and clean the window than solder on the rebar.
2- No I do not like Miracle Mudd.
3- Rebar can go horizontal,vertical, diagonal or any combination. It depends on the design.
Below are Putty 101 and Rebar 101 that I wrote awhile ago. It should answer all your questions.

Rebar 101
by Vic Rothman
There is a lot of debate about rebaring. I will attempt to clarify what rebar is and how it is used.
The term rebar means different things to different people. The round (sometime square)bars you
see in church windows are actually called saddle bars. The bars are set into holes drilled into the
window sash (removable window frame)or window frames(non-removable). The windows have
ties soldered to them at the solder joints. In olden days they used lead as ties, today it's copper
wires. These ties are twisted around the saddle bars. The purpose of the saddle bars is to
prevent the windows from being blown into the building, not support. At one time stained glass
was a real window out in the weather. The ties should not be made very tight, but should be
about one twist loose, thus the window can move in the wind. These bars are normally across the
shortest distance.
Next is flat rebar solder directly to the stained glass. These bars are sometimes drilled into the
sash and frames, or just run full length of the stained glass and put under moldings. These rebars
act like the saddle bars, but because they are soldered in place they also prevent the window
from deflecting near the bars. They will not hold up the windows.
Now we have real rebar. This can be thin brass strips referred to as "fins", sizes range from 1/4"
to 1" wide and about 1/32" thick. They are bent to conform to the lead or solder lines of the
windows and are run in every direction. Last year I worked on a Tiffany window made about 1920
that was 4'x 9 1/2' (it took 5 people to move it) the back was a maze of fins and the window was
perfectly flat. In copper foil window these fins can also go between the glass during construction.
But as with any flat rebar the strength goes from the width not just the thickness of the metal.
Thus a 1" wide bar is stronger than a 1/4" bar.
Rebar traditionally goes on the inside, because you do not want rain, snow etc getting on and
corroding the bars if there were outside. If there is outside glazing you can put the rebar on the
rear.
The placement of rebar is not rocket science. It is very logical. You put them perpendicular to a
lead line that might fold. Parallel lines, glass borders, concentric circles etc. In large windows you
may need rebar running through the center to prevent the window from flexing. Rebar is VERY
design and window location dependent. The size of the window does not matter. You can have a
12"x12" window that needs rebar and a 3'x3' that does not. If you design the lead lines well you
need less rebar. As for seeing the rebar get over it. Rebar is part of stained glass construction. If
done right it should not detract from a good looking window.

Putty 101
by Vic Rothman
Putty is made up of two basic ingredients. Whiting and linseed oil. Then there are various things
people add to the basic mix. I have broken this stuff into four categories.
1- Powders: whiting, plaster of paris, dental plaster, field plaster, portland cement.
2- Liquids: raw linseed oil, boiled linseed oil.
3- Thinners: mineral spirits,paint thinner,kerosene,white spirits,gasoline,turpentine
4- Driers: white lead, red lead, Japan drier.
The powders add bulk (makes putty thick). Whiting should be used alone. Plaster absorbs
moisture (moisture is the number 1 killer of building materials). Portland cement is so strong it
attaches itself to the glass making restoration very hard. Plaster and Portland cement NOT good.
Liquids are for turning the whiting into the putty mix. Should use 75% raw and 25% boiled linseed
oil.
Thinners are for making the putty mix more liquid for brush putty work as opposed to pushing the
putty with your fingers. These thinners evaporate quickly so that the putty sets up fast. This can
be a problem as it shortens the life of the putty.
Driers are used to speed up the setting time of the putty. White and red lead are now illegal in the
US. These things also shorten the life of the putty.
The last thing to add is color, if wanted.
The purpose of the putty is to add strength and to waterproof windows. For putty to work well, it
needs to stay elastic for as long as possible. That's why thinners and driers are not so good.
So who cares? Well, as someone who living comes from stained glass restoration, I do (all
stained glass windows will need restoration at sometime). It's been should that the above
problems can cause damage to a window in time. What is in time? 25+ years. Nothing happens in
the first few years of a windows life.
While most hobby work will end up in a land fill (please don't take offense)some of you might start
making architectural and church windows. That is when this knowledge is important.
Inland cement, Miracle Mudd and other putties contain some of the
NOT recommended ingredients. In the short term they all work, but if you want your work to last,
they should be avoided. You decide what you need to do.

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