Stained Glass Cement
Rhonda Dzanski
Leslye2
Someone looked in the archives and posted the contents to the group. I have
copied it below. I have included an article that explains what each
ingredients function is. Very interesting but makes it long. Hope it helps.
Leslye
<<Here ya go. This is a compilation of various threads relating to the
cement recipes.
--------------------------------------------------------------
From: "Michael J. Greer" <GreerS...@compuserve.com>
To: All <GL...@BUNGI.COM>
Charles ask that we post our cement recipe so here it is:
=
1 part Portland cement*
2 parts Plaster of Paris
4 parts whiting
1 part linseed oil
1 1/2- 2 parts mineral spirits or turpentine
lamp black or other "cement" colors (alkali proof) =3D
=
=
A "part" can be any measure - we use 1/2 cup portions. At this proportio=
n,
use about two
Tbsp. of color. We usually use black, but some might rather use yellow
ochre for brass
channel. *We've read articles that inclusion of Portland cement is of
questionable worth,
but Mike learned to make cement this way 20+ years ago and has been makin=
g
it that way
ever since. Any opinions?
After making cement, apply to your panel working the goo into the channel=
s.
Then dust
with whiting and clean off the goo with a palmetto brush (this is the bes=
t
part, because
this is where the lead takes on a really beautiful burnish). Save your
leftover, dirty whiting
from this stage to make your next batch of cement. Be sure to sift it
first. Leave the
panels sit overnight for the cement to set-up. Then detail in the mornin=
g
where the
cement has settled and oozed a bit in the corners. This technique is dirt=
y
and hard work,
but fast and worth every ounce of energy when you see the end result. Th=
e
only time it's
not a good idea is when your triple-glazing (sandwiching) which we avoid
whenever
possible.
Any better ideas or additions to this are welcome. =
Best regards, Dani Greer
--------------------------------------------------------------
From: "Michael J. Greer" <GreerS...@compuserve.com>
To: All <GL...@BUNGI.COM>
I'm going to post what I think is the corrected cement recipe per Julie's=
amendments:
=
7 parts whiting
1 part boiled linseed oil
1 1/2-2 parts mineral spirits
1-2 Tbsp. lamp black or other colorant
=
Someone (Len?) also mentioned japan drier - quantity would probably be
minimal. We haven't tried this out yet - any comments from the experts? =
Can Elisabeth give this recipe to her students? Any other
changes/improvements? Thanks for the feedback. Best regards, Dani Gree=
r
--------------------------------------------------------------
From: "Albert Lewis" <ale...@computer.net>
To: gl...@BUNGI.COM
=
> Exactly what =
> IS whiting?? My understanding is that it is powdered chalk; yet =
> other people tell me it's plaster, others again tell me it's a =
> mixture of chalk AND plaster; others again tell me it is dead, =
> inactive plaster. It's white so it's called whiting. There must be =
> more to it than that...
> So what is it exactly???
=
This from Julie Sloan's "Conservation of Stained Glass in America," =
<http://www.aiap.com/ with permission:
=
Traditionally, waterproofing compound was composed basically of boiled
linseed oil and whiting, with plaster of Paris to extend the mixture,
turpentine to thin it, red, white or yellow lead as a drier of the
oil, and lamp black to color the compound grey. These six ingredients
are found in most recipes for waterproofing putty from the nineteenth
century until the mid-1970s, when the use of lead was outlawed in the
US.
=
Linseed oil is a drying oil, used as the medium in artists' oil paint.
In waterproofing compound, boiled linseed oil is used because it dries
more quickly than unboiled oil. The process of drying is not a
volatilization; that is, nothing evaporates from linseed oil to leave
a solid behind, which is what happens when lacquers or watercolors,
for instance, dry. Instead, linseed oil oxidizes and polymerizes,
meaning that it absorbs oxygen from the atmosphere, which causes a
chemical change in the oil and results in its thickening and
hardening. A chemical change cannot be re-versed; set waterproofing
compound can never be dissolved to its constituent components of
linseed oil and whiting, unlike lacquer, for instance, which can be
dissolved in the medium in which it was applied originally.
=
This absorption of oxygen and subsequent chemical change begins to
take place when linseed oil is heated or exposed to driers or other
chemicals, or to sunlight. This is the beginning of the polymerization
process. Boiled linseed oil is not actually boiled; it is heated until
oxidation begins, but the boiling point is not reached. Today,
"boiled" oil is dried with chemicals. This drying process results in a
thicker substance which takes less time to fully polymerize.
Ultimately, when applied and left to set in the air, the fully
polymerized (or dried) oil becomes hard, very durable and waterproof.
Although full drying requires literally tens of years (especially in
thick applications, such as in a bevel), initial oxidation and drying
is achieved in two or three days, after which time a skin or harder
surface has formed which may be painted. Sunlight aids in the drying
process, although too much sun causes cracking.
=
Whiting is powdered calcium carbonate, or chalk. It is inert, meaning
that it reacts chemically with nothing. It has long been used as an
inexpensive and inferior white pigment in non-oil paints or an
extender for oil paints. Combined with linseed oil, it has a long
history as a putty used in repairing paintings, not to mention in the
glazing of windows.
=
Plaster of Paris is calcium sulfate. It is produced by roasting gypsum
(which is also calcium sulfate) to drive off most of the water bonded
to its molecules. This allows plaster of Paris to become active,
capable of readily and quickly re-combining with water to form a hard,
brittle material. This ability to combine with water is probably not
why it was used in putties, where such a hard-setting, brittle,
water-soluble material is not desired. While whiting is used as an
extender for oil paints, plaster was considered inferior for this use
because of its hygroscopic nature (meaning it absorbs water from the
air). However, in linseed-oil putty, plaster is used as an inexpensive
extender. In putty recipes, whiting is listed as the principle solid
ingredient. Putty can be made without plaster, but not without
whiting. While plaster is listed in many (but not all) recipes, it is
always in quantities smaller than those required of whiting --
typically, three or four parts whiting to two or three parts plaster.
=
Turpentine is the distillate of resin from coniferous trees. It is a
commonly-used solvent for oil painting, having a slower evaporation
rate, lower level of flammability, and lower toxicity than solvents
such as kerosene, which will also thin linseed oil. As turpentine
dries, it becomes thick and viscous, which adds to the putty-like
quality of waterproofing compound.
=
Red lead (Pb3O4) is made by heating white lead (basic lead carbonate,
2PbCO3.Pb(OH)2, the corrosion product of lead exposed to acetic or
other organic acids, used for pigments in white paints) or litharge
(PbO, also called yellow lead or massicot). None of these lead
products is commercially available in the United States today, either
uncombined or as part of another substance. Red lead is not primarily
used as a pigment in paints because it turns black or brown on
exposure to air, but its characteristic as an anti-corrosive made it
useful as the primary ingredient of rust-inhibiting paints. (The
familiar red paint used to prime iron and steel buildings and bridges,
most notably the Golden Gate Bridge, was red lead paint.) Although
white lead was, for many generations, the principle white paint
pigment, lead oxides are more important in paints and putties because
they are driers, added to linseed oil to hasten polymerization. When
lampblack is used to color the putty, which slows the drying process,
the siccative (or drying) nature of red lead becomes even more
important. The red lead in waterproofing compound may have served a
dual purpose: to help the waterproofing compound set, and to prime the
metal.
=
Since red lead is no longer used in waterproofing compounds, many
experienced glaziers and restorers feel that the waterproofing
compounds commercially available today are of inferior quality to
those available prior to the banning of red and white lead in the
United States. They do not set as well or last as long as red lead
waterproofing compound.
=
Lamp black (also called carbon black) is a fine, almost pure carbon
powder used as a pigment. It is the soot created from burning
petroleum oils, tars or resins. It has been used since time
immemorial as an oil pigment. Used as the coloring agent of
waterproofing putty, it will retard the drying of the linseed oil
unless driers, like red lead, are added. Today, when we cannot use red
lead in putty, it is important that the amount of lampblack used is
kept to a minimum.
=
The recipes for waterproofing compound found in stained glass manuals
vary. Amounts of materials differ or are not stated and other
materials are added depending on the author. These other materials
include Japan driers, "patent driers" (metallic salts, usually lead,
cobalt, or manganese) and gold size (a fast-drying varnish), added to
accelerate the drying of the linseed oil. Some recipes call for
"vegetable black" instead of lamp black. (This is a carbon black
pigment derived by burning vegetable matter rather than petroleum
products.)
=
The most controversial and potentially dangerous ingredient for window
putties is Portland cement. It is only in the last thirty to forty
years that Portland cement has found its way into glazing putties.
Portland cement is a calcined mixture of roughly three parts of
calcium carbonate (chalk or limestone) to one part aluminum silicates
(clay). Its name derives from the similarity in appearance and
hardness to Portland (England) lime-stone. Portland cement sets up in
much the same way plaster of Paris does, by reacting with water to
create heat. However, whereas plaster sets very quickly and is
ultimately rather brittle but soluble in water, Portland cement
continues to harden for a long period of time and results in a very
hard, insoluble material.
=
The reason this material is dangerous to use on windows is its
hardness. A leaded glass window must move with the expansion and
contraction of the lead came during thermal changes and with wind
pressure. As Portland cement hardens and becomes more rigid, it allows
the window to move less and less. Because the cement will not flex or
crack if the window is forced to move, the glass is likely to break.
In addition, because Portland cement is insoluble, it will be
virtually impossible to dismantle the panel without breaking glass. It
also exhibits excellent adhesion to glass, meaning that even if the
panel comes apart, the putty is very difficult to remove from the
glass.
=
Modern commercially available putties usually contain elastomers.
These are synthetic compounds designed to keep the putty elastic for
many years, preventing it from hardening up to a rock-like
consistency. None of these has been around long enough for us to know
exactly how long they will perform their task. In Europe, butyl mastic
is a favored putty with good aging characteristics, but its
workability is only fair and it is not presently available in the
United States.
=
Most of the recipes require that the waterproofing compound be mixed
with enough turpentine and linseed oil to render it somewhat soupy or
"thick as treacle" (molasses). It is scooped onto the panel and forced
under the flanges of the came using a natural bristle brush. Often it
oozes out the opposite side of the panel, which is desirable,
according to some of the handbooks, because then you know that the
putty has gotten into the groove of the came. However, be cautioned
that the putty should not be too runny or there will be nothing left
under the flanges when the oozing has stopped.
=
This soupy mixture is not recommended, however, if there is plating on
the window. Putty that is runny enough to ooze through the came will
continue to ooze between the plates. When plating is present, a stiff,
thick putty is a better choice, made by lessening the amount of
turpentine used to thin the mixture, or by adding more whiting. It is
applied with the thumb, because it is too thick to brush.
=
In much restoration, a thick putty is often recommended because it is
easier to control. Thumbing the putty keeps the spread of oil on the
glass in check, making cleaning easier. Also, because a stiff putty
does not ooze, cleaning will have to performed less often. In plated
windows, each layer of plating must be puttied before the next layer
can be soldered in place. This creates its own problems, though, if
the putty boils as the leads are heated for soldering. Care must be
used in this process. If fragile paint or glass exists, even if it has
been consolidated, it may not be desirable to subject it to the rigors
of being scrubbed with bristle brushes and oily putty. Paint or glass
that is textured could trap the putty and be very difficult to clean.
=
Regardless of whether thick or thin putty is used, cleaning the panel
after puttying is crucial. Studies in Europe have shown that the oils
in putty, if not properly cleaned off the glass, will eventually
corrode glass paint. Liberal dusting and rubbing with whiting is the
most effective, although some glaziers also swear by sawdust. Use of
any of these should be accompanied by wearing a dust mask to prevent
aspiration of the dust. As the putty sets, further cutting back and
cleaning may be necessary to remove oils that travel to the surface.
--------------------------------------------------------------
From: wo...@telalink.net
To: gl...@bungi.com
=
Here is the cement recipe I was given when I learned to do leaded
windows: 1 part boiled linseed oil, 1/2 part turpentine, color, and
enough whiting to make the consistency that you wish. For color we use
black paint tint from the paint store. A little goes a long way. I mix
my cement to a thick consistency and thumb push it under the lead came.
I clean up with whiting, let it sit for 24 hrs., then turn and repeat
for the other side. I clean the glass with Hi-Sheen, then rub polishing
compound over the came, dry to a haze, rub off, add black patina, let
dry thoroughly, then brush. I use a horse hair brush (brush made of hair
from horses) to polish the lead to a shiny black. =
Question: Is there such a thing as black whiting or how would one tint
it black? Not very often, but sometimes I get just a few spots that tend
to show some of the white color of the whiting that I used to clean it.
The horse hair brush usually takes care of it, but it would be nice not
to have it to begin with.
=
Sandy
Creations In Glass
---
Charles Spitzer
cha...@az.stratus.com
Customer Assistance Center
Stratus Computer, Inc.
Phoenix, AZ
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> What is the best homemade recipe for cement to use in lead panels?
Ginger
thanks for the recipe, I keep forgetting how to mix it.
Chemo the Clown
> On Friday, September 11, 1998 at 3:00:00 AM UTC-4, Rhonda Dzanski wrote:
nicole hansen
Maybe no one will ever see this, but I just wanted to thank Albert Lewis for the detailed cement comment. I did some pretty deep research to find this page and it does not disappoint (unlike the other online cement resources).