Donna Nicholas on mon 20 aug 12
I have a large (4'x3'x7') unglazed reclining figure in my yard. It
broke in the firing, and the artist repaired it with thinset and
epoxy. It's been there for more than twenty years, and has held up
pretty well. However, the PC-7, PC-11 joints become brittle and
fail, and the thinset doesn't seem to hold very long either. I'm
about to repair it once again, and wonder if anyone out there has had
experiece with any adhesives that might hold better.
Snail Scott on wed 22 aug 12
On Aug 20, 2012, at 9:46 PM, Donna Nicholas wrote:
> I have a large (4'x3'x7') unglazed reclining figure in my yard. It
> broke in the firing...the PC-7, PC-11 joints become brittle and
> fail, and the thinset doesn't seem to hold very long either...
I have had work (fired in sections or repaired) outdoors for
twenty years, attached with PC-& and PC-11, with no visible
degradation of the joints. So, I can't say what went wrong with
yours. A few possibilities, though: PC-& and its kindred have a
shelf life, and the older the stuff gets in the can, the more fragile
and brittle the joint will be. (No data, just personal observation.)
Epoxy from an old package can appear to set properly, but
the joint will be brittle and prone to early failure. I know of no
better material for such joints than epoxy, however. No adhesive
I know of will match the durability of the clay itself (not many
things do!), so it's not a valid standard. The joint will always fail
before the clay, but a good long run of a few decades seems
reasonable. When you re-do the joint, make sure the epoxy is
a new batch, not some that's been sitting in your studio for a
few years. (My rule of thumb is two years, then chuck it out,
but of course that's not a magic number; the degradation is
gradual. (I write the date of purchase on the container.) If the
joint has failed (broken apart), use a grinder to remove as much
epoxy residue as possible before re-doing the repair.
When I do a unglazed outdoor piece, I make a flange where the
clay parts will join, in order to increase the surface area of the
joint (and stabilize the clay against distortion in firing), but of
course that's not a option with a repair. If the clay wall is thick
enough, though, I apply epoxy out to within 1/8" (3mm) of the
surface, or a bigger gap if the depth allows. You need enough
epoxy to be strong, but you've got to leave space for the filler.
I clear the joint back with a stick so the channel is straight-sided,
not 'U'-shaped. When the epoxy is set, I roughen it with very
coarse sandpaper. (Wrap it around a stick to get into the tight
joints.) All this is to allow the mortar to have enough depth and
'tooth' to lock in and have some strength. Too shallow a groove
makes for weak mortar, I find. I tint regular white mortar with
oxides to match the clay color, add grog or sand to mimic the
texture of the clay and then work it in, strike it flush with the
surface, then let it set. (It's a good idea to test the color first, to
see how it looks when dry. Dark colors often set and dry much
paler.) The mortar will be a good match for the bare clay, but
it's not a good adhesive, so you need the epoxy, but the mortar
will protect the epoxy from UV, extending its life.
I have no idea whether this is how your piece was made, but it's
the best method I have found after a number of years of trying.
The oldest pieces I have joined or repaired by this method are
about 20 years old now, and the joints still look good. I don't
expect them to outlast the clay, but clay can last centuries or
more. Whether they will still look good in 30, 40, 50 years...I
will have to wait and see.
Best of luck!
-Snail
James Freeman on wed 22 aug 12
On Mon, Aug 20, 2012 at 10:46 PM, Donna Nicholas
wrote:
I have a large (4'x3'x7') unglazed reclining figure in my yard. It
broke in the firing, and the artist repaired it with thinset and
epoxy. It's been there for more than twenty years, and has held up
pretty well. However, the PC-7, PC-11 joints become brittle and
fail, and the thinset doesn't seem to hold very long either.
Donna...
Epoxy (which is what PC-7 is) is, indeed a marvelous adhesive. It's one
major drawback is that it breaks down rather quickly when exposed to UV
radiation. Inside your house, your epoxy repair would last almost
forever. Outdoors in the sunshine, however, it will always fail. Outdoor
epoxy needs to be at least shaded (such as within the socket joint of a
multi-part sculpture), or better yet, painted.
When the "Sparty" statue at Michigan State University, the world's largest
free-standing ceramic sculpture, was repaired, the gentleman doing the work
used one of the West System epoxies, mixed with terra cotta clay as a
filler. I have called the technical people at Gougeon Brothers (the
manufacturer of West System epoxies) on a number of occasions to seek
technical advice and product recommendations for various projects, and they
have been incredibly friendly and helpful. You are speaking to the actual
chemists, and they know their stuff. If you give them a call, I am sure
they will be able to tell you precisely what was used to repair Sparty and
give you ideas on avoiding or mitigating the UV issues.
http://www.westsystem.com/ss/
For a cementitious repair, try using polymer fortified tile grout,
available in a rainbow of colors. I repaired a crack in the driveway of my
first house with some leftover grout. When I visited the house over ten
Michigan winters later, the patch was still sound. Fired clay is not
concrete, but I am guessing it will still work.
Good luck!
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Nefsigh@AOL.COM on wed 22 aug 12
Dear James and all
I have had an earthenware work outside since 1987--glued segments together
with PC 7 the work is 7 feet by 3 by 2--and it has been unprotected.
Surface had a very light glaze was on-wash off to highlight texture and
then nothing else done.
PC & joints are still holding with no issues. Exposure has been direct to
sun, rain, wind, snow, ice storms, freezing rain and tornados,
While I know epoxies usually break down very quickly in UV Hence the clears
turning a nicotine brown and becoming brittle), this work has simply not
broken down-and I do go check as the main reason I put it out there was to
test the adhesive.25 years isn't bad.
Anyway-=3Dthere also used to be a #M Hotline-- a 1-800 number that I used =
to
call to find different glues for odd circumstances. The person doing the
repairs might check to see if it still exists and give them a call-Whenever=
I
called, they were very helpful and seemed to enjoy the challenges I
presented.
Good Luck
Lenny Dowhie
In a message dated 8/22/2012 1:15:34 P.M. Central Daylight Time,
jamesfreemanstudio@GMAIL.COM writes:
On Mon, Aug 20, 2012 at 10:46 PM, Donna Nicholas
wrote:
I have a large (4'x3'x7') unglazed reclining figure in my yard. It
broke in the firing, and the artist repaired it with thinset and
epoxy. It's been there for more than twenty years, and has held up
pretty well. However, the PC-7, PC-11 joints become brittle and
fail, and the thinset doesn't seem to hold very long either.
Donna...
Epoxy (which is what PC-7 is) is, indeed a marvelous adhesive. It's one
major drawback is that it breaks down rather quickly when exposed to UV
radiation. Inside your house, your epoxy repair would last almost
forever. Outdoors in the sunshine, however, it will always fail. Outdoor
epoxy needs to be at least shaded (such as within the socket joint of a
multi-part sculpture), or better yet, painted.
When the "Sparty" statue at Michigan State University, the world's largest
free-standing ceramic sculpture, was repaired, the gentleman doing the wor=
k
used one of the West System epoxies, mixed with terra cotta clay as a
filler. I have called the technical people at Gougeon Brothers (the
manufacturer of West System epoxies) on a number of occasions to seek
technical advice and product recommendations for various projects, and the=
y
have been incredibly friendly and helpful. You are speaking to the actual
chemists, and they know their stuff. If you give them a call, I am sure
they will be able to tell you precisely what was used to repair Sparty and
give you ideas on avoiding or mitigating the UV issues.
http://www.westsystem.com/ss/
For a cementitious repair, try using polymer fortified tile grout,
available in a rainbow of colors. I repaired a crack in the driveway of m=
y
first house with some leftover grout. When I visited the house over ten
Michigan winters later, the patch was still sound. Fired clay is not
concrete, but I am guessing it will still work.
Good luck!
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
James Freeman on wed 22 aug 12
On Wed, Aug 22, 2012 at 2:54 PM, wrote:
I have had an earthenware work outside since 1987--glued segments together
with PC 7 the work is 7 feet by 3 by 2--and it has been unprotected.
PC & joints are still holding with no issues. Exposure has been direct to
sun, rain, wind, snow, ice storms, freezing rain and tornados,
Good to know, Lenny. PC-11 has UV inhibitors. I was unaware that PC-7
did also.
Here is an article from West Systems on weathering of epoxy:
http://www.epoxyworks.com/28/pdf/weather_forcast_destruction.pdf
They offer a hardener with UV inhibitors built in, but they still suggest
three coats of UV inhibiting varnish over it if it will not be painted.
I have a huge daddy long legs spider sculpture in my yard, high fired
stoneware body sitting atop welded steel legs, about 4' tall, 6' leg span.
I used Bondo to make a bed for the ceramic body by simply applying the
Bondo to the top steel member holding the legs together, then setting the
body in place. The Bondo by itself is fused forever to the steel, but let
go from the stoneware after about one year. I then epoxied the body to the
Bondo bed, and it's been holding firm for about 5 or 6 years now. That
epoxy is almost completely shaded from the sun by the ceramic body.
Take care.
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
Nefsigh@AOL.COM on thu 23 aug 12
Correction: That was a 3M Hotline number--
In a message dated 8/22/2012 3:22:11 P.M. Central Daylight Time,
Nefsigh@AOL.COM writes:
Dear James and all
I have had an earthenware work outside since 1987--glued segments together
with PC 7 the work is 7 feet by 3 by 2--and it has been unprotected.
Surface had a very light glaze was on-wash off to highlight texture and
then nothing else done.
PC & joints are still holding with no issues. Exposure has been direct to
sun, rain, wind, snow, ice storms, freezing rain and tornados,
While I know epoxies usually break down very quickly in UV Hence the clear=
s
turning a nicotine brown and becoming brittle), this work has simply not
broken down-and I do go check as the main reason I put it out there was t=
o
test the adhesive.25 years isn't bad.
Anyway-=3Dthere also used to be a #M Hotline-- a 1-800 number that I used =
to
call to find different glues for odd circumstances. The person doing the
repairs might check to see if it still exists and give them a
call-Whenever I
called, they were very helpful and seemed to enjoy the challenges I
presented.
Good Luck
Lenny Dowhie
In a message dated 8/22/2012 1:15:34 P.M. Central Daylight Time,
jamesfreemanstudio@GMAIL.COM writes:
On Mon, Aug 20, 2012 at 10:46 PM, Donna Nicholas
wrote:
I have a large (4'x3'x7') unglazed reclining figure in my yard. It
broke in the firing, and the artist repaired it with thinset and
epoxy. It's been there for more than twenty years, and has held up
pretty well. However, the PC-7, PC-11 joints become brittle and
fail, and the thinset doesn't seem to hold very long either.
Donna...
Epoxy (which is what PC-7 is) is, indeed a marvelous adhesive. It's one
major drawback is that it breaks down rather quickly when exposed to UV
radiation. Inside your house, your epoxy repair would last almost
forever. Outdoors in the sunshine, however, it will always fail. Outdoo=
r
epoxy needs to be at least shaded (such as within the socket joint of a
multi-part sculpture), or better yet, painted.
When the "Sparty" statue at Michigan State University, the world's larges=
t
free-standing ceramic sculpture, was repaired, the gentleman doing the
work
used one of the West System epoxies, mixed with terra cotta clay as a
filler. I have called the technical people at Gougeon Brothers (the
manufacturer of West System epoxies) on a number of occasions to seek
technical advice and product recommendations for various projects, and
they
have been incredibly friendly and helpful. You are speaking to the
actual
chemists, and they know their stuff. If you give them a call, I am sure
they will be able to tell you precisely what was used to repair Sparty an=
d
give you ideas on avoiding or mitigating the UV issues.
http://www.westsystem.com/ss/
For a cementitious repair, try using polymer fortified tile grout,
available in a rainbow of colors. I repaired a crack in the driveway of
my
first house with some leftover grout. When I visited the house over ten
Michigan winters later, the patch was still sound. Fired clay is not
concrete, but I am guessing it will still work.
Good luck!
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
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