Rev. 9/1/96 1/18/97 2000-08-04, 2002-07-13; 2003-01-07, -06-19, 2004-12-18,
2005-04-12, -06-26, -11-05, -12-02, 2006-01-22, 2007-03-20, -05-23, -07-02, 2008-02-26,
2009-03-19, -04-10, -09-17, -12-19, 2010-03-15, -09-01, 2011-02-14, -11-20, 2012-07-11. 2013-12-25
|On making bottles historically, here is a site with lots & lots of
detailed info and images.
Glassmaking and Glassmakers Page
|And since someone asked me
Bottle Neck Guitar Slider
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|Bottle Cutting Overview
Cutting flat glass is fairly easy. Glass is usually cut by scribing a distinct scratch with a diamond or carbide tipped tool and then bending the glass along the scribed line, with fingers or pliers or over a dowel or edge and the glass will crack along the line. Curved lines and circles are normally run (making the crack run along the line) by tapping on the opposite side of the scratch just ahead of the crack proceeding through the glass which can be seen as a silvery surface inside the glass. More
The great problems with cutting bottles are that it is hard to scribe an even, continuous line on the bottle - juggling the cutter and bottle and turning the bottle, the glass of the bottle often varies in thickness, and, if tapping is done, it has to be done inside the bottle to be opposite the scribed line. Possibilities 2005-04-12
To be specific, Sawing will go any way through the bottle (diagonal, vertical or across) and is expensive; Hot Wire will separate around the bottle very cleanly and is relatively low cost, while Freehand is cheapest but requires practice.
|Having decided to do a considerable rewrite of this
section, I have changed the order to best
results to worse in my limited experiments and tests. Of course, a
good result may cost too much for a particular user.
An e-mail question about not being able to find commercial versions of the wire cutter is correct - other than the commercial wet diamond band saw, there are no commercial/professional versions of any of these. Bottle cutting is a cheap hobby with limited market. Glass artists use large lapidary blade saws to cut solid glass or band saws either of which can go for more than $1000.
|Laser/Water Jet - I queried firms that make the equipment and I was correct in what I learned from their sites: that laser cutting will not work on bottles due to the size and lack of maneuverability of the head and abrasive water jet cutting will probably not work due to the violence and spreading of the jet inside the bottle although working under water may allow it.|
|Suddenly I have made considerable progress in testing devices for doing things under this topic. The goal here is to either run a scribed line by applying stress or not even having to scribe, but breaking the bottle evenly enough that the edge will not further crack and grinding is minimal.|
|[I am thinking of actually testing some of the more extreme methods mentioned herein, such as wrapping the line with a nichrome wire and heating the wire (a transformer is required); wrapping the line with kerosene or lighter fluid soaked string and lighting the string; filling the bottle up to the line with water and touching the line with a hot bar or poker; filling it with oil and plunging in a hot poker.]|
One solution often ignored because of low cost or the size of bottles is to buy or rent a tile cutting saw and carefully saw through the bottle. This may require considerable patience depending on the thickness of the glass. A tile saw may not work on thinner glass bottles if it is too coarse and sets up shattering vibrations.
Also available, but not for rent, are band or wire saws that are designed for wet cutting. This means the metals are protected from corrosion and the motor is up high enough to avoid the water (most wood and metal saws have the motor down low.) The lower cost ($150-200) versions of these are sold for stained glass work and may not have a large enough throat to take a bottle. Band and wire saws cut slowly and may break the bottle or the band if pushed faster than the cutting easily occurs.
In a recent project, I explored cutting wine bottles with various sawing tools in a worst case scenario of a diagonal cut across the shoulder and neck. Attempting to hold the bottle in a standard rock saw clamp resulted in the bottle quietly breaking as soon as the strength of the shoulder was cut. On the other hand, a very large glass cutting band saw with a 1/2" wide diamond blade went through the glass easily in several minutes. This kind of saw costs $500-2,000 or more. [2012-07-11 Delphi band saws - even larger size may lack clearance for some bottles.] 2007-03-20. [Added note: This casually wine bottle was sawn without detailed care and not finished, so the end of the cut (lower left) has broken free and the top edge is very sharp. The white material inside is powdered glass from the cutting silted in the cutting water. The original provided to me as a model had been finished in that all sharp edges were rounded and the flat edge somewhat polished. The whole clear bottle was sand blasted which disguised the partial finish on the cut. 2009-09-17] An elaborate use of bottles, and perhaps the source of my example, is the transGlass line from Artecnica which are made in Guatemala in a local enrichment program. 2010-12-01
Hand Sawing -
Here is an alternate suggestion that may work for some - note the "(though
Almost every mention of bottle cutting includes a reference to using a hot wire to crack the glass, usually with very few details. Usually mentioned are a low voltage power supply and nichrome wire, sometimes with a reference to foam cutters. The simple facts are that the wire has got to be used like the string (above) to stress the glass and either run the crack along the score or crack the glass locally without a score. The wire must wrap the bottle to stress it all at once because glass cracks are notorious for wandering off to the side, ruining the even edge. This is quite unlike a foam cutter which uses a wire under tension to make progressive cuts like a hack, band, or coping saw blade.
The low voltage power supply is possible, a fairly heavy battery like a car battery probably being required, as a couple of flashlight batteries, as used in miniature scenery cutters, will not last long with a longer wire. The low voltage supply ideally should be adjustable but it does not have to be DC so a household doorbell transformer, if of enough wattage would work. An ideal tool is a Variac, a variable transformer with a dial. Many variable voltage power supplies sold for electronics work may not have enough amperage.
The problem as I see it is that the wire must wrap around the bottle, bottles come in different sizes so the wrap must also, nichrome wire becomes stiff and brittle when heated, and if an even break is to occur, the wrap must pass close to itself, possibly creating a short circuit across a fairly high amperage supply.
My answer is to take a longish piece of wire, several times the length needed to go around the bottle, so if a short occurs the extra length will cushion the short. One end of the wire should be fastened on a the end of a rod or board, making the loop immediately, then the rest of the wire goes along the rod to an adjustable point making a d or p shape. The electrical connections are at the ends of the wire. For testing a variable power supply and a heavy switch to apply the current suddenly will be used. Based on my nichrome experience, it may be necessary to have two loops, one for wine and soda bottles and another for gallon jugs because of the stiffness of the wire once heated. 2005-04-12
So, I have finally, 2005-11-09, built and run the
design shown in the pictures below, which mostly follows the model described above. [Push
F11 in Internet Explorer for a larger window.] A wooden board has porcelain fence insulators
screwed to each end (A). Ceramic fiber board covers the top of the board
(blanket could be used) glued with water glass. A wire is twisted around one
insulator and ends formed into a hook. On this hook is placed a 3" medium weight
spring that will stretch to about twice its length (E). Kanthal A-1 wire is
looped at the end and hooked on the other end of the spring (E). At the other
end of the board, the wire is pulled past the insulator and between two washers
mounted on a bolt with a wing nut for tightening two washers (A). Using a
bottle for size, the wire is looped around at the cutting point and pulled
firmly to stretch the spring and clamped with the wing nut and washers (A).
Alligator clips are used to make the connection to the wire in a flexible way
The measured resistance for the wire I am using is 5 ohms. From previous
tests, I found it took about 5 amps to get the wire to a low red heat, so I
would need 25 volts. My Variac is rated to 7.5 amps and fused at that.
[2010-11-03 I am trying to assemble a "kit" for people to use - a test run today
showed the wire being 28" long measured 4.2 Ohms and 26 VAC for red heat which
computes to just over 6 amps and 157 watts and 24 gauge wire. I will try 24 VDC,
The pictures of the Coke bottle inadvertently show why the break nearer the neck is not even. As the wire heats it gets longer. The spring should take up slack and keep the wire on the bottle, but did not in this case. I was taking pictures of the loosened wire (C, E above) and the bottle (A below), and did not notice that the bottle was no longer square (A) or did not think it mattered because the wire seemed evenly looped on the bottle. The neck snapped off, but with a long sharp point (C, D). A few minutes later, I set up on the ribs below the label. This time the bottle stayed square, the wire tight (I braced the bottle) and the break was clean (B, D below). The wire softens in use and on cooling retains the shape of the ribs (D above)
The Sprite bottle sequence shows steps in a clean run. In B, the bottle is position to be twisted into the loop and the wire adjusted closely, square, and in the right position on the bottle (C). This bottle was the second I snapped for pictures and in A it can be seen tilted, but resting for the snap. A weight was positioned after the picture was taken because the bottle kept shifting under tension of the wire. For the third bottle (the clear one above) I decided the block should both prop it up level and block it from rolling. I used a handy lead ingot. E below shows the bottle just after snapping with the wire still in place and D shows the edges. Careful examination of the break will show that it not perfectly flat and I will say that the edges are generally very sharp - it should be ground on a piece of emery paper on flat glass or another grinding surface. But this is the best result of the various methods worked here. 2005-11-19
Conclusions Having a heavy duty variable power supply, at least 5 amps, is certainly handy. Variacs of this capacity are often available used for much less than the current $65 retail price. If a car battery of 12 volts is used, then the wire has to be selected to get to red heat on 12 volts, which means thicker wire of lower resistance. Two car batteries in series, totaling 24 volts or a 24 volt truck battery might be a choice. One source of thin wire is the coil of replacement wire for the foam cutter mentioned above, sold in hobby and some hardware stores. Using a household dimmer for wattage control will require more care in handling, because it is actually producing spikes of voltage much higher than the average needed for the amperage.
Followup: In the spring of 2007, I became involved in a project to cut across the neck and shoulder of wine bottles at a sharp angle. [Conclusion: use a glass cutting band saw as wire and lapidary saw did not work.] I rebuilt the wire cutter for possible production use.
|The left end of the wooden bar fixed above was cut, shaped
and drilled for a wooden pin to hinge the last 8 inches as shown. The
wood pin hinge was expected to be tighter and keep the bar aligned better
than a steel hardware hinge of small size. It worked well. Power was
supplied via alligator clips as shown, but they were moved in so that the
ends of the wire did not get heated, which made fastening the cutting part
of the wire easier. A foot switch was made from a heavy duty push switch
mounted in an outlet box. Ceramic fiber board scraps were used to make
a level surface to lay the bottle on. When tapered beer bottles were
worked other scrap pieces supported the bottle at level.
[All images may be seen larger by clicking on them.]
|An overall view of a bottle in position shows the added ceramic fiber board so the bottle lays level resting on added structure below the wire bar used alone above. Note that in this picture the wire does NOT properly wrap around the bottle. As mentioned above, the wire is longer than needed to wrap the bottle so that if it touches at the crossover point, it will not dead short the supply.|
|The hot wire being applied to the bottle. The path of
the wire is somewhat distorted by the varying thickness of the bottle.
Positioning the bottle and wire is critical to a clean cut. The wire
has to run across the bottle and since it will stretch, tension must be
maintained and it will move on the bottle. When doing these, I had my
left hand on the pivoted part of the arm for tension, my right hand* on the
neck of the bottle and one foot on the switch. The bottle was yawed to bring
the wires almost in touch but not quite. When heat was applied, if the wire
moved on the bottle, I released the switch and adjusted.
The bottle normally breaks on the cool down, so judgment must be used as to how long to apply power. I counted seconds and did a bit of trial and error - 30-35 seconds for this rig. If desired, a drop of water guarantees a break if ready. If no break, let the bottle cool briefly.
*and the middle hand for the camera? 2007-05-23
Cutting glass with a fine tipped torch is old news having been used in the automated glassware industry for decades and by certain art glass goblet makers. The problem for most of us is the very small hot flame and turning the bottle. One choice is discussed below. I was told of a goblet maker who sheared his by setting them on an old record turntable. I recently received a phone call from a guy (who promised photos) who said he used the miniature oxy-butane torch that uses tiny tanks that look like the CO2 cartridges used in seltzer dispensers and he spin his bottles by tying a yoke on the neck so it hangs straight and twisting the hanging long cord so it spins for a while. As with hot wire, the glass may crack on cooling rather than heating. 2009-09-17
I took various parts I had around and combined them into a rotating bottle
holder and "cut" a couple of bottles with a fine tip welding torch - worked good
with and without scoring. Following comments on CraftWeb about using a
record turntable, a carbide scratcher and a very small torch, I headed for the
Even the best cuts require smoothing and polishing as described at the end of Freehand.
Here are previous notes.
The tools needed are a simple glass cutter used for flat glass, a trough to hold the bottle, and a rod to tap the score around the bottle. These are described in the process description below.
The proper way to cut bottles is to use a glass cutter (like for window glass, cheap at the hardware store), placing the bottle in a V-shaped trough (Two pieces of wood nailed at edge with another to act as stop for the foot.) Add a brace or hold the edge at the correct point so the cutter is held fixed (it helps if the wood is wide enough so the hand can rest on the wood, say 1x4" wood for ordinary bottles) and the bottle rotated underneath it. Do not go over the score repeatedly, do it once and don't waste time after scoring the bottle, it becomes harder if you wait - it "heals".
scoring the bottle, a metal rod bent at the end is inserted in
the upright bottle and the glass is tapped, starting a crack,
which can be seen as a silvery surface in the glass, and worked
around the line on the bottle. The rod is most effective if it is
heavy enough (3/16" or 1/4") to have its own momentum
and if a rubber or wooden ball is drilled and mounted on the rod,
then adjusted to rest on the neck so the bent end hits the same
point down in the bottle every time. The bent end should be very
short (especially for cutting wine bottles with small necks) and
the tip should be sharpened to a blunt point for precision. With
a stiff rod, it may be necessary to bend the tip long (1")
to be able to bend it then saw it off short (3/8") and point
it with a file. The middle of the rod may have to be bent to
reach the wall of the bottle in bottles with long narrow necks
and steep shoulders. Check this before scoring the bottle (shown
straight in drawing, would have to bent to get near shoulder.
This shows an alternative way of attacking a bottle. The bottle was cut by laying it in the open gap between two 2x6 boards in an outdoor bench. The hand was rested on the board in front, holding the cutter and the bottle was rotated with the other hand. This gives good support for the hand, but the larger V is needed with a bottle bigger than this, in my opinion, or a board needs to be set under the hand to raise it up. When cutting the bottle lengthwise, it is held with one hand and the cutter used pushing straight down. This picture can serve as warning because I cut myself rather deeply on the finger. I had left the neck laying in the groove and was cutting the long line when the cutter slipped off the glass and I banged my finger on the very sharp edge of the neck, putting a cut about 1.5" long perhaps to the bone, but in line with the tendons and muscles, so a strong bandage replaced several times a day and it is healing. The damage you see to the bottle was from trying a medium head torch on the scribe lines to break the glass - not very successful as breaks occurred in long curves in addition to following the neck. 2002-02-07
This is a (failed though interesting) attempt to take apart a bottle and make a bowl in one step. Originally the bowl was to be donated to the Empty Bowls so the label material - which I can't test for lead - was put on the outside. Obviously the bottle was a Corona beer (inset) and I chose it because it was 1) Laying on my front yard where it shouldn't be and 2) it had light thin clear glass. The bottle was first cut around the neck and tapped on the outside to run the crack, leaving a piece like the neck in the picture above. Then the base was cut off around the side and tapped from the inside (more efficient, less force required.) Then the cylinder of the body was scored up the sides and tapped inside to break it into front and back. The back was scored inside (also easier) and divided in half. The bottle neck was then cut apart into pieces. and the whole arranged in a bowl mold for fusing The problem was that while the side pieces sagged and fused nicely into place, the small pieces from the neck, instead of filling the gap, fell or folded down into the bowl, leaving an open gap in the bowl shape. The inset shows the bottom of the bowl (click to enlarge image) If the bottle was screen printed hot, the label will normally survive fusing. This one was also run through the dishwasher to test it. 2002-02-07
|Burning String - I used several soda bottles that I had collected for
fusing and tried several variations. I did not find the results
satisfactory, but they may be in some cases, so read on.2004-12-18
I came across two videos showing the use of acetone (nail polish remover) that produced better results than shown here. In each case they tie cotton string on the bottle, remove the string and soak it in a small container of acetone, replace the string, light it and turn the horizontal bottle on its long axis while the flame burns with no smoke, then plunge the bottle into water to snap it. In both videos only a very brief view of the edge is shown but it appears that both have rough spots. Beer bottle http://www.youtube.com/watch?v=_A4J7RcdsfM&NR=1&feature=fvwp Wine http://www.youtube.com/watch?v=AHxpW60x_KI&NR=1 good captions 2010-03-28
In a further variation which I have encountered several times just recently but not tried, again the string is tied tightly around the bottle and removed, but this time soaked in lighter fluid in a small bowl before being returned to the bottle and lighted from the bottom with the bottle horizontal so the flame climbs up and around. When a crack is heard cold water is dribbled on. Appears to be a cleaner break and no soot. I have no lighter fluid to test. 2013-12-25
My first tests were on even walled (Sunkist orange soda) bottles, where I scribed a line, wetted a string in denatured alcohol, tied it in place and lit it. The alcohol evaporated and burned so quickly as to provide no heat to the glass. I was also frustrated that the string I knew to be cotton was too thin and new string I had bought turned out to be nylon or polyester in spite of not being marked.
I bought a heavier cotton string at the grocery store. I switched to kerosene because of its slow evaporation rate. On scribed bottles, with two wraps of string placed just below and touching the scribed line and the bottle standing upright, the flame produced a distinctly audible crack at about the end of burning time. It also produced a black sooty surface. Unfortunately, the crack followed the scribe halfway around the bottle and then continued 1/4" higher for the other half. Worse, there was a errant heat crack that curved about 1/2" below the scribe. So the bottle was cut, but a lot of grinding would be required to produce an even rim. Several additional tests were run with essentially the same result. [In the image, the scribe line is just barely visible against the soot about 1/4" below the back rim. Note the dip in the rim cut at the front above the lower bulge of the S. The white visible inside the bottle is the background for the blue lettering on the other side of the bottle.
Then it occurred to me that the flame would stay along the string if I laid the bottle on its side, propped on a fire brick so the burn line was out in the air. This produced less soot and a more controlled flame and with the scribed line, cracked free, but the crack varied above and below the scribe by 1/8th inch or more and branch heat cracks showed up.
I decided to try some tests with just the burning string, no scribe. This seemed to give results that were as good (or bad) as previously on the even walled bottles. I pulled out a couple of old classic Coke bottles. Here scribing the line is a real problem. Above the label the bottle is curved, making scribing on the sloping shoulder difficult for me. Below the label, the bottle is ribbed making for an uneven surface backed by uneven thickness. Almost any crack around the bottle would improve on what I have gotten in the past.
After I wrapped the string soak in kerosene, tied it with an overhand knot, arranged the ends nicely along the other strands, lit the fuel and stood and watched. And watched. And watched. The flame went out and the bottle didn't break. I got a small scoop of water and touched the drip to the string - ta ta!! Nice crack. It wandered as much as the scribed bottles without the scribe hassle. I took off the bottom of the same bottle (around the ribs) and worked a couple of other bottles, getting the same results.
So, a burning string works to cut a bottle if 1) a medium heavy smooth cotton string is used; 2) with kerosene, not alcohol; 3) with the bottle on its side; 4) with the ends carefully tucked in; 5) and a large drop of water is applied to the string as soon as the fire is out;
IF an edge is OK that varies up and down by a good fraction of an inch and will have to be ground down a bunch to make a drinking glass or goblet AND the loss of 1 in 3 or 1 in 4 due to branch crack (which keeps running when grinding is done.) [2005-11-19 After doing the wire snapping below and seeing how even a small deviation from square can lead to a big point, I think a better choice on the string would be to use finer string and go around twice with the knot running under both strings so its width is a smaller proportion of the burning line.]
|Bottle Neck Guitar
Slider I was contacted by someone in the UK to make a
guitar slider from a wine bottle neck and after looking on the Internet
decided the effort in international mailing since a
the UK makes them in different styles. But I wandered to a
from 6-8 years back and thought some of it was worth borrowing.
Guitar sliders require tuning the guitar to an open chord (so it sounds a chord when strummed) and then a hard object (because using the finger across all the strings gets painful) is slid along to make other chords. The Hawaiian steel guitar is played flat with a steel slider, but the slider can be a piece of steel or brass held edgewise between two fingers or a tube slipped over a finger. The tube can also be glass, which is why there is a section here, and the traditional is a piece of wine bottle neck for the thicker glass.
Note that getting the neck off the bottle, however scored, is easier than cutting the bottle, since leverage will snap the neck.
an McWee From: Worcestershire, England
edroperFrom: Seneca Falls, NY
Even further comments:
Subject: Re: Bottle Cutter? From: email@example.com (Douglas
3/14/98 In article <350AF691.757D@digitalexp.com>, Suz writes:
Subj: cutting beer bottles
|How can I get a smooth rim( similar to those on purchased glasses) on the
wine bottle I've cut ?
That rim is called 'fire polished'. Store bought glasses have it done right at the end of the blowing operation when the glass is separated from pipe by using a tiny hot flame and rotating the glass - the tiny blob at one point on the rim is where the last bit lets go. Hand made blown glasses have a fire polished edge because they are shaped hot. The only* (usually impractical) way to do it with bottle glass is to preheat the cut piece to about 1000F and while hot, hit the edge with a torch and then anneal. [but see below*] The torch should be compressed air or oxygen with propane as drawing hot kiln air into an air/propane torch works poorly. Acetylene does not work well on glass, depositing carbon in the glass and overheating quickly - it is too hot.
The rim is the flaw in making cheap glasses from cutting bottles. Basically you have to smooth it in several steps to a point it is acceptable to your mouth. If done without a belt sander it can be done with a selection of small grinding wheels or by hand. Hand is most easily done by taking some flat glass and using rubber cement to glue down emery paper in a few different grits. Inverting the glass on the surface of the coarsest and adding a little water will quickly level the rim. Then turning the glass at an angle will permit taking the sharp outer edge off. If the process is repeated with finer grits it will get a finer and finer haze on the ground part and less gritty feel. The inside edge can best be done (without small grinding and buffing wheels) by cutting emery cloth into 1" strips and making a shape like a small hacksaw from 3/4-1" wood so the emery cloth can be applied flexibly across the edge. Again coarser grits will take the sharp edge off and a succession of finer grits will smooth it. 2007-07-02, 2009-04-10
The image shows a hacksaw blade mounted to a board (which is cut to fit diagonally in a tray holding full sheets of sandpaper) that allows tearing off narrow strips. Small washers under the blade leave a gap for the paper. The two handles below the blade are used to tension the narrow strips inside the curve so that the abrasive can work the inside edge and round it. Several grades of emery (black) paper are needed to first shape the edge then smooth it to take off roughness. For ultimate smoothness and polish, a polishing drum in a Dremel type tool may be needed. 2007-08-15
When I used a fine point torch to cut bottles
on a turntable, I was startled to see the lack of cracking at least in
fairly thin soda and beer bottles I used for testing. When asked in an
e-mail about heating edges for smoothing I first suggested building an open
top mini-kiln with a turntable so the cup could be preheated and set in,
turned automatically without the overwhelming heat and volume of the
kiln/annealer, with the rim above the edge of the mini-kiln while the
element keeps the glass warm. After hitting with a hot torch, the cup
is quickly returned to annealer. Then I had a second thought and
felt that a test of the turntable and torch without the mini-kiln might be
worth it to see if quick lifting out and return with padded tongs, trusting
the thin glass to have low enough tension to survive. I would put a
frax board or pad on the table to keep it from chilling the thicker base,
especially without the preheating that would occur in the mini-kiln.
(The image shows glasses clearly cut with a torch because the etched frost on the bottle has been melted clear around the edge.)
For pictures of drill bits and techniques, go to
----- Original Message -----
The most basic rule of drilling glass is that it must be drilled
wet. For a bottle, the easiest solution is to fill the bottle with water and
cork it. Then, in any case, surround the site with plastic clay (the stuff kids
used to use at school - Plasticine, an oily clay, not Sculpy) that will make a
dam for water above the glass. If you are going to do a lot, you can set up a
rig to submerge the whole bottle and support it under water.
----- Original Message -----
Date: Thursday, June 19, 2003 7:55 AM
From: Soper, Mike [mailto:Mike.Soper@sclot.com]
Link to Bottle Labels
To change the form of a bottle all you need is an oven that can reach about 1400°F, which all pottery kilns and most glass annealers can do easily. For the result to survive cooling, either the kiln must lose heat especially slowly or there must be a controller that will take the temperature down slowly. If the bottle is cooled too rapidly, it will shatter from the stresses inside.
If the kiln is tall enough, it is easy to stretch a bottle. More. If the heating elements are in the walls, it not being a good idea to get glass on them (besides the glass will probably shatter from local heating if too close to the element), a wire must be stretched across the top of the kiln from which to hang a loop of wire in the center. The neck of the bottle is fixed in the loop. When the temperature is raised, the bottle slowly stretches as the temperature passes well beyond 1100°F. If it watched through a peep hole, when the desired stretch is achieved, the lid is opened, letting the temperature drop to about 1000F and freezing the glass in shape.
If a bottle is laid on its side on a kiln shelf, it can be heated until it slowly sags and the heating can be continued until it is flat or nearly so. Normally the first form the bottle takes is a cylindrical cup - the top sags down pulling in the sides. A cup shape can be used for ash trays (for the few people who still smoke) or a spoon holder. For a more predictable shape, white potter's clay can be formed, dried, pre-fired, painted with kiln wash for separation, and the bottle placed on, thus sagging the bottle into a form. Clay molds on my warm glass page.
LABEL USE - A cute trick is to soak a paper label carefully off a bottle, sag it to a new shape, then wet the label again [or keep it wet and soft] and form and glue it to the new shape as though the paper label survived the sagging. Use a water soluble glue like Elmer's white glue or mucilage. Treat it like a decal. More and more beverages are using clear plastic printed labels which can be peeled off, but putting them back smoothly can be a problem.
The bottles at the right show the three styles of labels. The brown bottle has paper labels. The green one has a closely trimmed plastic label, slightly peeled at the upper curve. The clear bottle has a silkscreened (or decaled glaze) label (next.) Because the mold seam would mess up the applied label, there is an indent below the back label to orient the bottle during application. The seams are on the side between the labels. Location of the seams on paper or plastic labels is random. They are applied to cold bottles. 2010-09-01
The silk screened 'paint' used on bottle labels (like a glass Coke bottle, Corona beer and this Mexican water brand) is high temp enamel applied while the glass is hot and it will survive being fused. Thus it is possible to take apart a bottle (with a glass cutter), rearrange the words or parts of glass, fuse them together and make a statement (a short one) or decoration with the rearrangement. Here is an experiment with a Corona beer bottle re-arranged. To avoid/reduce the visual damage to the label (as here), it should be flattened or molded with the label not touching the support which may require watching the sagging to use a rod to spread the glass to stop it from folding under.
The creative efforts I have seen with slumping bottles have usually involved using a couple of bottles or cutting the bottle apart, so that a puddle of glass with the form of a bottle when it is done. This cannot be done in one step - the bottle does not melt like ice from the bottom, so the fused lower part must be created then the upper worked to it.
Q: lisa47 wrote:
A: Almost any kiln (as in borrowed) will do this, but you have to
have a peep hole to watch it. It can be done on a kiln shelf
covered with kiln wash. Ten at a time is way too many for
anything but a custom sagging/fusing kiln and you just can't do this
on multiple shelves.
2002-05-15 I use a shelf
wash from Paragon Kilns in Mesquite Texas for my glass sagging
and fusing. You will need something if you don't want it to
stick to the shelf and not have residue on the glass.
Bottle Neck Melting & Stretching
|Suddenly there appeared from the internet a rec.crafts.glass thread (far below) referring to an eBay sale (just below, right) and an e-mail showed up with a couple of clues including size and the fact the cooker worked (just below, left.) So follow my rather sudden progress. 2005-11-05|
|I am truly stuck. 30 years ago when I
worked the carnival route, the big item were stretched coke and beer
bottles. The device was invented by Steve Jackson at Viewmont High School
It utilized a #10 can on a stand with heating coils inside. The bottle was attached above with a hook. As it heated, it dropped to the stand below, the bottle stretched to a total of give or take 20 - 24 inches. They were given away as prizes.
I have tried on the web to find one of these simple kilns for six months on the web and through carnies to no avail. Can you help me? "
From: "Vincent Verdekal"
Subject: Bottle stretching
Date: Thu, 3 Nov 2005 17:01:59 -0600
Bottles sold on eBay Oct. 2005 (image with permission)
If 1" of frax, then 4 1/8" ID. Make of hardware cloth instead of steel to eliminate lots of hole drilling. 12.96" circumference - 3 loops= 39", 4 loops=51", 6" straight at each end, bent double to 3" for connections, small IFB chunk for pass through. 2005-11-04
|These bottles, which have liquid inside, were emptied and reshaped, then the liquid was returned and the cap replaced.|
|To make the bottle neck
melter, using clues so far, I
looked up #10 cans on the internet and found they were basically 6"D x 7"H.
After considering a sheet metal shell and having to drill numerous pairs of
holes to support the element, I decided on hardware cloth. It will
give you some idea of the junk in my shop when I mention that I built this
from stuff that is around.
The shell or cage is two pieces of the welded wire material called 1/2" hardware cloth. I could have used one long piece, two was less wasteful. It could have been one layer, but I felt it was too weak. Six inches OD times Pi gives 18.85" for circumference and length, so I cut 19.5" to get overlap. With two pieces, I misaligned the seams (one left, one upper right in picture) fitted the ends of wires into the holes and added 22 gauge wire, twisted to hold together.
|To provide an exit for the element ends, a 1" thick piece of insulating fire brick was cut from a scrap with a used hacksaw blade and trimmed to 2x3". The sides were then cut in 1/2" all around and two holes were drilled at an angle with a carbide bit. Note that the tools, if not carbide, are not usable for cutting other stuff afterward because IFB is abrasive and dulls edges.||Wires were cut to make a 1x2" hole and the brick piece inserted through. A simple wire U held it although it is probably not needed as the blanket will hold it in the hole.|
|One inch thick ceramic fiber blanket was cut 7" tall and long enough to fit. This blanket is sold in rolls. If you want only enough for this kind of project, check with a commercial heating and air conditioning place where it is used as high temp insulation, otherwise buy the roll from a refractory supplier. Cutting it long enough to fit is a bit tricky. For the 6" ID of the cage, it should be 19" long. For the 4" nominal ID of the unit it should be about 13" long. The answer is that it is cut to the longer length and stuffed into the cage. (below right.)|
|The 1000 watt electrical element is one made by Eagle Electric for replacement in old style heaters. They no longer make it, but Elliott's Hardware, Dallas TX, holds the remaining stock (which I bought when I worked there) and will ship. Alternately, a 1000-1200 watt element can be bought made up by Giberson and many other sources or wound from wire.||In this case, I pulled off 4" at each end,
straightening it, and folded it back at the 2" mark and twisting. This
gave a thicker connection point and twice wire so it runs cooler. The
coiled portion was then stretched to make 3 turns around the inside 4"
diameter - 39". If I were making another, I would stretch to about
42-44 for the reasons given below.
As shown in the upper left, a screwdriver was used to make holes through the blanket in line with the drilled holes and the triple loops of the coiled element were fitted inside (below) with the leads through the holes.
|The small inserts (right) show the cage stuffed
with the blanket, the element positioned inside with no support clips yet,
and some of the clay saddles. The main picture shows an inside view
with the clay saddles wired over the coil and through the blanket. The
clay saddles were arbitrarily made of white pottery clay, dried, prefired to
1350F in the annealer and then full fired in the glory hole to about 2100F.
A better saddle might have just the right opening to hold the coil.
The flared corners keep the retaining wire in place.
I was worried about the coil being too long, since it is not easy to recompress. As it was, it was too short, the saddles compressing the blanket and making the ID larger (the 1" blanket being compressed to 1/2-3/4" thickness.) So the coils are shown taking shortcuts between the saddles. I put both hands inside, like a muff and stretched to wires after installation.
|A short length of 12 gauge extension cord was given a grounded plug at one end and crimped on loop terminals on the hot wires at the other. A short length of solid wire was butt crimp connected to the ground. The ends of the elements were looped and bolted to the terminals. A wire stand-off was twisted in place and then around the cord (right edge.) The end of the ground wire was bolted to the cage. 3M fiberglass electrical tape was put around the connections to reduce the risk of contact. A small wire cage was built to keep fingers off the 120 volt terminals.|
|The montage at right shows the first bottle
done in the melter. The cage was propped up on the edges of 2
firebricks and the bottle wired in place as shown. The bottle neck was
held between two wire U's tightened to the edge of the cage. A
thermocouple was inserted at the top. The thing was plugged in and
waiting started. Originally the bottom of the bottle was even with the
bottom of the cage so the overall view shows it emerging as the neck
stretches. When the bottle sat on the platform, the plug was pulled.
The temperature was up over 1450F for this fairly thin glass bottle.
Being a long time glass guy, I was really touchy about annealing, so I cooled the piece by lifting the lid and dropping to about 1100, then letting it cool at its own rate. At a couple of hundred, I took the lid off and released the wires. Lifting it out with padded tongs, it cooled to air temp without cracking (right.)
|The montage below shows details, mostly of the second run with a shorter Coke bottle and the firebricks standing on end. The cage was turned over so the extra blanket can be folded in to trap the heat better. The glow of the elements is visible through the blanket. The final temperature was just over 1500F. The five small pictures show the bottle emerging from the cage as the neck stretches with the result on the right. A clock showing the pace would have been useful, but it took just a couple of minutes once the bottom started moving. (click for somewhat larger view)|
|To the right is end of one bottle still wired
in place, somewhat distorted, showing the coils, while the next picture
shows the third bottle with a long curved neck and below that the mess left
behind. (click for larger view)
Since the first two bottles survived cautious treatment, I decided to try bending or shaping the neck. Donning heavy welders' gloves, I grabbed the bottom as it dropped, tipped off the blanket cover and began cutting the wires holding the neck. Minor disaster - the wires wouldn't cut because they were so hot and my selection of diagonal cutters just mashed the wire. While I am fighting with the wire, the glass touches the hot coil (still plugged in to a GFCI outlet) and sticks. So I stop moving the bottle, get a piece of metal to tap the coil free. The bottle survived the abuse (middle) but now the coil is messed up and will take some careful work - the coil material gets brittle once heated and cooled (bottom.)
So what else - a different grip that does not distort the top, a different release or different cutters for the wire.
|All 8 messages in topic - view as tree
Oct 31, 1:37 pm show options
From: "Phil" <fil...@gmail.com> - Find messages by this author
Date: 31 Oct 2005 11:37:40 -0800
Local: Mon, Oct 31 2005 1:37 pm
Subject: stretching bottle necks
I know that a similar question was asked not long ago, so forgive me for trying to squeeze a little extra info from you experts. How do you stretch the neck (alone) of a bottle - as I'm sure you've all seen, the neck can be stretched and twisted massively while the rest of the bottle retains its shape.
I'd be very grateful for any guidance on this.
Nov 3, 8:58 pm show options
"I love your site. I know nothing about glass. I have a question though... Would it be possible to reheat and then reblow a magnum or double magnum champagne bottle into almost a sphere? Or at least a pooched out champagne bottle? "
In principle, yes. Reworking a bottle of some smaller
size is something almost every modern glass blower does at some point. The
method is to preheat the bottle(s) in the annealer so they are about 1000F,
below but very near the point where they will sag of their own weight. From a
broken piece of a similar bottle, glass is melted on the end of a blow pipe.
This step is necessary because ordinary art glass melts at lower temperatures
than bottle glass and using art glass as the bond makes the connection
uncontrollably soft, even with beer bottles, much less the heavier wine bottles. The
glass is heated, flattened and shaped, the end of the pipe reheated and brought
in to match the opening in the bottle, making a good seal. The bottle is lifted
out and taken to the glory hole where it is brought up in temperature until it
is soft enough to begin to blow out and shape. If the bottle is too cool going
in, it shatters (or cracks) perhaps making a real mess in the glory hole.
a bottle is preheated in a kiln, it can rather easily be picked up from the
bottom on a punty (unlike the difficulty mentioned above
using a pipe on the top) in order to flare or turn out the top. Bill Riker
reworks milk bottles as shown and other types shown on his
site. Because of
the evenness of the rim we can be pretty sure these were reworked in a glory
hole rather than with a torch. As with a pipe, it is important to melt
similar glass on the punty end rather than using art glass because of the
different melting temps - a broken piece of bottle preheated in the kiln and
picked up by the thin skin left on an almost clean punty can be melted to make
|CLEANING BOTTLES - If you have to clean out narrow necked containers, plastic or glass, of material like mold, dirt, wine stain, crystallized sugar, etc., a valuable trick is to keep a couple of tablespoons of aquarium gravel. These small stones have rounded edges and when put in the container with water and soap or other solvent matched to the stain, can be swirled around the inside while holding the container horizontal with my hand over the neck, providing a scraping action that is hard to duplicate with a brush. When done, I pour off most of the liquid then give the bottle a swirl and turn it upside down in a small container so the gravel pieces fall down into the neck and then into the container without being driven by the bulk of the fluid even if the container overflows. Then I pour off the liquid in the small container and use it to store the gravel for next time. 2009-12-19|
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