Not all glass is created equal, which means that it is not all compatible either. While this wouldn't be a big deal if I only ever made beads using one color per bead, but that would be very boring for me and for you!
One of the first things new glass artists learn is that the COE, Coefficent Of Expansion, of the glass colors being used must all be the same. What's that, you say?
I know that sounded like a bunch of boring science-speak, so let me boil it down for you. When glass gets hot is expands. As it cools, it contracts. In order for a glass bead or any other object to survive the annealing and cooling process, the amount that each glass expands and contracts must be the same as all of the other glass in the piece.
If one color expands twice as much as the others, it will expand and contract too much, and the beautiful piece of art will crack and sometimes break apart due to the stress this incompatibility causes.
One minor exception is frit if used sparingly. Many of the frits on the market do not match the COE of the soft glass, but they have a secret that will enable them to be compatible when used on the surface of a bead as decoration. What's their secret? The lead content in the glass enables it to be compatible with glass that has a COE that is close to the frit. It is not so compatible that it can be covered with clear glass, a process known as encasing.
However, a thin layer on the surface of the bead can be used quite successfully as long the frit does not comprise more than five percent of the bead's glass. This is called the 5% Rule in glass circles.
If you have any questions or would like to suggest topics, I can be reached through this blog or through my web site or shop at
http://LampOfLuxury.com/
http://burningscentsations.etsy.com/
Have great afternoon!
Showing posts with label quality. Show all posts
Showing posts with label quality. Show all posts
Wednesday, December 5, 2007
Saturday, December 1, 2007
Batch Annealing And You (Because I Won't Do It)
Now that you know a bit about kilns and the annealing process, you should probably know that there are two schools of thought on how to anneal--Immediate and Batch Annealing.
Immediate Annealing
When using immediate annealing, after the bead is created in the torch and has cooled sufficiently to no longer be molten or soft, but is still very hot, it is put directly into pre-heated kiln and starts to anneal, you guessed it, immediately.
In my kiln I have a Kiln Couch (this where I got mine:HeritageGlass.com (scroll down a bit)), which is a rack that allows beads to be placed into the kiln so they do not touch the floor or the other beads. After I've made several more beads or when the racks fill up, I move beads to the floor of the kiln where they can now safely touch each other without any worries.
This is the safest method of annealing since the risk to breaking or cracking of the bead is very low once it has been placed into the kiln. Since I make some very large beads in addition to smaller ones, this method is really my only option in order to ensure that all the beads come out of the kiln as they went in--in one piece.
Batch Annealing
During this type of annealing, the kiln is even turned on while the lampworker is making their beads. When a bead has been completed, it is placed either into a hot crock pot of vermiculite or (worse yet) a fiber blanket.
Both the vermiculite and the fiber blanket slow the cooling of the glass in an effort to prevent the stress from breaking the bead as it cools. While the crock pot does add heat to the vermiculite, it cannot approach the temperature needed to actually anneal the beads.
Once a group of beads is ready for annealing at some point in the future, they are all placed into a kiln which is then slowly heated to the correct temperature for the annealing process. Once the kiln is back at room temperature, the beads have been annealed and are ready for use in jewelry or other applications.
It is not uncommon for this process to result in a few broken beads when the process has completed simply because the stress in the beads could not endure being reheated in the kiln.
This type of batch annealing is most often employed by new lampworkers or lampworkers who do not yet own a kiln of their own., but there are many lampworkers (that also own kilns) who swear by this process. For me, I've never been comfortable with gambling the life of my beads on a crock pot.
If you have a different point of view, have any questions or would like to suggest topics, I can be reached through this blog or through my web site or shop at:
http://www.lampofluxury.com
http://BurningScentsations.etsy.com
Thanks for stopping by!
Immediate Annealing
When using immediate annealing, after the bead is created in the torch and has cooled sufficiently to no longer be molten or soft, but is still very hot, it is put directly into pre-heated kiln and starts to anneal, you guessed it, immediately.
In my kiln I have a Kiln Couch (this where I got mine:HeritageGlass.com (scroll down a bit)), which is a rack that allows beads to be placed into the kiln so they do not touch the floor or the other beads. After I've made several more beads or when the racks fill up, I move beads to the floor of the kiln where they can now safely touch each other without any worries.
This is the safest method of annealing since the risk to breaking or cracking of the bead is very low once it has been placed into the kiln. Since I make some very large beads in addition to smaller ones, this method is really my only option in order to ensure that all the beads come out of the kiln as they went in--in one piece.
Batch Annealing
During this type of annealing, the kiln is even turned on while the lampworker is making their beads. When a bead has been completed, it is placed either into a hot crock pot of vermiculite or (worse yet) a fiber blanket.
Both the vermiculite and the fiber blanket slow the cooling of the glass in an effort to prevent the stress from breaking the bead as it cools. While the crock pot does add heat to the vermiculite, it cannot approach the temperature needed to actually anneal the beads.
Once a group of beads is ready for annealing at some point in the future, they are all placed into a kiln which is then slowly heated to the correct temperature for the annealing process. Once the kiln is back at room temperature, the beads have been annealed and are ready for use in jewelry or other applications.
It is not uncommon for this process to result in a few broken beads when the process has completed simply because the stress in the beads could not endure being reheated in the kiln.
This type of batch annealing is most often employed by new lampworkers or lampworkers who do not yet own a kiln of their own., but there are many lampworkers (that also own kilns) who swear by this process. For me, I've never been comfortable with gambling the life of my beads on a crock pot.
If you have a different point of view, have any questions or would like to suggest topics, I can be reached through this blog or through my web site or shop at:
http://www.lampofluxury.com
http://BurningScentsations.etsy.com
Thanks for stopping by!
Tuesday, November 27, 2007
Pucker Up - A Hallmark of Quality
I'm Blogging on my lunch break today, so I'll need to keep this one short.
Today, I'd like to talk about puckered ends...no not your end or mine for that matter, but the ends on beads around the hole.
A sure sign of well made bead is that the area around the hole on both ends of the bead are puckered, that is, they dip toward the hole in a smooth curve and there are not points or jagged edges which could possible fray or cut the medium they will eventually be strung onto.
When wrapping glass onto a mandrel, a steel rod that will eventually be removed to create the hole in the bead, the footprint of the bead should be evenly wrapped so that the glass creates this round pucker naturally.
Due to the physics of glass (which I won't bore you with, I promise), it naturally wants to be round and gather toward the center of the mass on the mandrel. When a beads footprint is wider than the amount of glass wrapped, the bead will form a football shape with very sharp ends around the hole.
If the bead is going to be shaped, either in a press or by marvering (rolling the bead on a surface to shape the glass), then this shape is sometimes necessary when wrapping. However, in the final bead when all shaping has been completed, there should not be any sharp or jagged points.
During the summer, I attended an art fair in a lampworker was selling necklaces made of beads that obviously where too wide and had jagged points on their ends. She'd hidden these flaws by using some rather large bead caps in her jewelry.
This is just something to keep an eye out for when buying beads on-line or in finished jewelry that I think everyone should know before putting down your hard earned money. If you get a bad bead from another artist, that may well put you off lampwork from other artists, and that would be a shame.
As always, if you have any questions or would like to suggest topics, I can be reached through this blog or through my web site or shop at:
http://www.lampofluxury.com
http://BurningScentsations.etsy.com
Have a great day!
Today, I'd like to talk about puckered ends...no not your end or mine for that matter, but the ends on beads around the hole.
A sure sign of well made bead is that the area around the hole on both ends of the bead are puckered, that is, they dip toward the hole in a smooth curve and there are not points or jagged edges which could possible fray or cut the medium they will eventually be strung onto.
When wrapping glass onto a mandrel, a steel rod that will eventually be removed to create the hole in the bead, the footprint of the bead should be evenly wrapped so that the glass creates this round pucker naturally.
Due to the physics of glass (which I won't bore you with, I promise), it naturally wants to be round and gather toward the center of the mass on the mandrel. When a beads footprint is wider than the amount of glass wrapped, the bead will form a football shape with very sharp ends around the hole.
If the bead is going to be shaped, either in a press or by marvering (rolling the bead on a surface to shape the glass), then this shape is sometimes necessary when wrapping. However, in the final bead when all shaping has been completed, there should not be any sharp or jagged points.
During the summer, I attended an art fair in a lampworker was selling necklaces made of beads that obviously where too wide and had jagged points on their ends. She'd hidden these flaws by using some rather large bead caps in her jewelry.
This is just something to keep an eye out for when buying beads on-line or in finished jewelry that I think everyone should know before putting down your hard earned money. If you get a bad bead from another artist, that may well put you off lampwork from other artists, and that would be a shame.
As always, if you have any questions or would like to suggest topics, I can be reached through this blog or through my web site or shop at:
http://www.lampofluxury.com
http://BurningScentsations.etsy.com
Have a great day!
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