what temp to soften glass so gravity makes it flow

Michele Blank wrote:

again, the problem lies in the fact that the bottom is really, really, thick
but the rest of the bottle is thin like wine bottles. i do these to support
my habit. www.bottlemeltdown.com if anyone is interested. m

I'd try it to support my habit but I doubt anybody would by Kamchatka
bottles.

--
Jack


http://photos.yahoo.com/bc/xmissionbobo/

you would be surprised!!!!!

"nJb" wrote in message
...
Michele Blank wrote:

again, the problem lies in the fact that the bottom is really, really,
thick
but the rest of the bottle is thin like wine bottles. i do these to
support
my habit. www.bottlemeltdown.com if anyone is interested. m

I'd try it to support my habit but I doubt anybody would by Kamchatka
bottles.

--
Jack

I do bottles all the time. If I go to 1,500 in my kiln I get a puddle that
gives little hint of once having been a bottle. I do have a controller and
would start by holding it at 1,350 for 30 min. If not slumped enough I'd try
1,400. I agree that a soak at 1,200 does nothing. When I have glass that's
1/2" think I slow down the annealing, from about 950 to 700, so that a whole
firing takes about 24 hours.

John Bassett

I see them at craft fairs with the original label glued back on the now
flattened bottle, and used as ashtrays, or wind chimes. They have so many
different ones that I always thought they were fired to 1200-1400 and then
flattened mechanically all at the same time?

--
JK Sinrod
Sinrod Stained Glass Studios
www.sinrodstudios.com
Coney Island Memories
www.sinrodstudios.com/coneymemories

It is probably the case that someone built a 4x4 foot, not very deep
slumping kiln and does a couple of dozen bottles at a time, redoing those
that don't slump enough. They may also have a mold for part of the shape.
No matter the choice of glass the basic pattern is:
Find the sag point (where a long thin piece of glass slowly sags of its
own weight when supported at ends.)
Calc the annealing point at 50C/90F below the sag point for practical
purposes
Heat the glass up slowly enough that it does not crack going up until
past the sag point.
Heat as fast as possible to the desired slump, observing when possible
and safe.
Crash cool from the slump temp to the annealing temp to stop the
movement of the glass and prevent devitrification (white patterns on the
glass from decomposition.) This is normally done by opening the lid several
times.
Soak at the annealing point to bring it all to the same temp and little
strain.
Slowly cool the glass from the annealing point to the strain point over
several hours depending on thickness of the thickest piece. For most soft
glass, the strain point can be taken as 300F below the annealing point.
Continue cooling as fast as the kiln will drop to near room temp.
http://users.ticnet.com/mikefirth/techspec.htm

I have thought it would be neat to have a couple of annealer/ovens handy
so one could be holding the glass for annealing or fusing and the other
could be running from annealing to slumping and back down again. Then the
worker could stack the 900F slumped glass in the annealer, move new
bottles/forms at 900F to the slumping oven, etc. Of course, the real
problem is that most artistic fusing can't be handled this way as it is a
balancing act of fragile proportions.

--
Mike Firth
Hot Glass Bits Furnace Working Website
http://users.ticnet.com/mikefirth/hotbit46.htm Latest notes

"jk" wrote in message
. ..
I see them at craft fairs with the original label glued back on the now
flattened bottle, and used as ashtrays, or wind chimes. They have so many
different ones that I always thought they were fired to 1200-1400 and then
flattened mechanically all at the same time?

--
JK Sinrod
Sinrod Stained Glass Studios
www.sinrodstudios.com
Coney Island Memories
www.sinrodstudios.com/coneymemories

The information on establishing the high end annealing temperature of an
unknown glass is not quite accurate. I would recommend the following.

You will need a rod approx.18" long and about the thickness of a pencil
fabricated from the glass you will be slumping. This rod is suspended at one
end between two IFB's. Raise the temperature as fast as you want to as a rod
of that dimension will be able to take a quick temperature rise. Since we're
talking soda lime glass we can assume it will anneal in the mid to high
900's but we don't know. Raise the temperature to about 1000 deg. F. and
hold it there for 1 hr. Check the rod if it is still straight raise the
temperature another 50 deg. and hold for an hour. If it is not deflected at
all raise it another 50 deg. and hold an hr. When you see a slight
deflection of the rod you have found the softening point of that glass.
Check the temperature reading on your pyrometer. The high end annealing
point is 50 deg. F or 28 deg. C below the temperature reading on your
pyrometer not 90 deg F. The temperature where the glass has deflected is
called the softening point. You can get into trouble if you anneal 90 deg.
below the softening point. One cannot assume the strain point to be 300 deg.
below the annealing point as one has to mechanically measure that point and
that can only be done at a testing lab that has that type of equipment. In
reality strain points are really only necessary when doing thick castings
and not necessary for what most do on this board.


Mike Firth

It is probably the case that someone built a 4x4 foot, not very deep
slumping kiln and does a couple of dozen bottles at a time, redoing those
that don't slump enough. They may also have a mold for part of the shape.
No matter the choice of glass the basic pattern is:
Find the sag point (where a long thin piece of glass slowly sags of its
own weight when supported at ends.)
Calc the annealing point at 50C/90F below the sag point for practical
purposes
Heat the glass up slowly enough that it does not crack going up until
past the sag point.
Heat as fast as possible to the desired slump, observing when possible
and safe.
Crash cool from the slump temp to the annealing temp to stop the
movement of the glass and prevent devitrification (white patterns on the
glass from decomposition.) This is normally done by opening the lid several
times.
Soak at the annealing point to bring it all to the same temp and little
strain.
Slowly cool the glass from the annealing point to the strain point over
several hours depending on thickness of the thickest piece. For most soft
glass, the strain point can be taken as 300F below the annealing point.
Continue cooling as fast as the kiln will drop to near room temp.
http://users.ticnet.com/mikefirth/techspec.htm

I have thought it would be neat to have a couple of annealer/ovens handy
so one could be holding the glass for annealing or fusing and the other
could be running from annealing to slumping and back down again. Then the
worker could stack the 900F slumped glass in the annealer, move new
bottles/forms at 900F to the slumping oven, etc. Of course, the real
problem is that most artistic fusing can't be handled this way as it is a
balancing act of fragile proportions.

"Henry Halem" wrote in message
...

You will need a rod approx.18" long and about the thickness of a pencil
fabricated from the glass you will be slumping. This rod is suspended at
one
end between two IFB's.

I think that you mean suspended between two IFBs, one at each end of the
rod, Henry.

Or are you using the old softening point determination method, where you
follow the position of the end of the vertically-suspended rod or fibre with
a travelling microscope as the temperature rises?
--
Terry Harper
http://www.terry.harper.btinternet.co.uk/

Gee, Henry, thanks for the info, except I thought that the last time you
corrected me, you were the one that said 50C (90F) not 50F. In any case,
isn't a 50F step a little big, especially if you are going to back off 50F
for annealing, and hold for an hour a bit long?

--
Mike Firth
Hot Glass Bits Furnace Working Website
http://users.ticnet.com/mikefirth/hotbit46.htm Latest notes

"Henry Halem" wrote in message
...
The information on establishing the high end annealing temperature of an
unknown glass is not quite accurate. I would recommend the following.

You will need a rod approx.18" long and about the thickness of a pencil
fabricated from the glass you will be slumping. This rod is suspended at
one
end between two IFB's. Raise the temperature as fast as you want to as a
rod
of that dimension will be able to take a quick temperature rise. Since
we're
talking soda lime glass we can assume it will anneal in the mid to high
900's but we don't know. Raise the temperature to about 1000 deg. F. and
hold it there for 1 hr. Check the rod if it is still straight raise the
temperature another 50 deg. and hold for an hour. If it is not deflected
at
all raise it another 50 deg. and hold an hr. When you see a slight
deflection of the rod you have found the softening point of that glass.
Check the temperature reading on your pyrometer. The high end annealing
point is 50 deg. F or 28 deg. C below the temperature reading on your
pyrometer not 90 deg F. The temperature where the glass has deflected is
called the softening point. You can get into trouble if you anneal 90 deg.
below the softening point. One cannot assume the strain point to be 300
deg.
below the annealing point as one has to mechanically measure that point
and
that can only be done at a testing lab that has that type of equipment. In
reality strain points are really only necessary when doing thick castings
and not necessary for what most do on this board.


Mike Firth

It is probably the case that someone built a 4x4 foot, not very deep
slumping kiln and does a couple of dozen bottles at a time, redoing those
that don't slump enough. They may also have a mold for part of the
shape.
No matter the choice of glass the basic pattern is:
Find the sag point (where a long thin piece of glass slowly sags of
its
own weight when supported at ends.)
Calc the annealing point at 50C/90F below the sag point for
practical
purposes
Heat the glass up slowly enough that it does not crack going up
until
past the sag point.
Heat as fast as possible to the desired slump, observing when
possible
and safe.
Crash cool from the slump temp to the annealing temp to stop the
movement of the glass and prevent devitrification (white patterns on the
glass from decomposition.) This is normally done by opening the lid
several
times.
Soak at the annealing point to bring it all to the same temp and
little
strain.
Slowly cool the glass from the annealing point to the strain point
over
several hours depending on thickness of the thickest piece. For most
soft
glass, the strain point can be taken as 300F below the annealing point.
Continue cooling as fast as the kiln will drop to near room temp.
http://users.ticnet.com/mikefirth/techspec.htm

I have thought it would be neat to have a couple of annealer/ovens
handy
so one could be holding the glass for annealing or fusing and the other
could be running from annealing to slumping and back down again. Then
the
worker could stack the 900F slumped glass in the annealer, move new
bottles/forms at 900F to the slumping oven, etc. Of course, the real
problem is that most artistic fusing can't be handled this way as it is a
balancing act of fragile proportions.

Mike Firth wrote:

Gee, Henry, thanks for the info, except I thought that the last time you
corrected me, you were the one that said 50C (90F) not 50F. In any case,
isn't a 50F step a little big, especially if you are going to back off 50F
for annealing, and hold for an hour a bit long?


If I'm trying to establish this sort of thing I'm moving in 10's.

--
Jack


http://photos.yahoo.com/bc/xmissionbobo/

Go up about 500/hr to around 1500F


all good tips -- but many mention of Grey Goose bottles

--- what about the enamel on them??????
if it is low temp enamel -- it's going to go bye bye at those temps.....


Cheryl
DRAGON BEADS
Flameworked beads and glass
http://www.dragonbeads.com/