Annealing requirements

[Travis Frink]

I have been helping a girl at the public studio here with some larger (by local strandards) solid pieces and it made me realize how little I know about annealing of larger work.

The pieces we are working on are between 3 and 5 inches in diameter and 18 to 15 inches tall- cylinderesque in shape. I dont know how much they weigh. The studio staff seem to think that the studio standard "overnight" annealing "in the back of the annealer" (it's a 4-foot-deep cave) is good enough. As i said, i know little on the subject but it seems short based on what i have seen at other studios (but they were using SP). Does anybody have any ideas on this?

Are there any general guidlines on how much annealing time is needed based on how thick or heavy the piece is?

Do different soda glasses (SP, Gaffer, spectrum....) have different annealing times?

Do inclusions of layers of metal foils and colors effect annealing requirements?

Thanks for your thought on this.
Travis

[Ben Solwitz]

I don't have much experience annealing thick pieces but overnight sounds way too fast for me. The general rule of thumb is an hour per 1/4" from the annealing point to the strain point. Have you tried annealing any pieces like this, how did they come out? Looking at a couple of annealing charts in glass notes, one for blown ware cooling from two sides and one for castings, they recommend soaking at the annealing temp for 16 hours and cooling from the annealing temp to the strain point for 50-100 hours. Seeing as these pieces are neither blown nor cast, neither of these are probably the best schedule. I would tend to think you could go faster than the low end of 50 hours since you don't have an even wall thickness of 4" all the way around, but I'm not going to speculate how fast. It might require some experimentation but I'm sure there are some people around that have annealed similar work who can offer more advice than I can.

[Michael Mortara]

we make work that size and our cycle is 170 hrs (5") we saw cut them later.
hope she is not selling her work.

[Pete VanderLaan]

While I might not go as long as Mike suggests, It is at the very least a 72 hour to 90 hour cycle. The only real proof is looking at the finished work in a polarizing screen. You can buy plastic polarizing screens from Edmunds Scientific very reasonably. The only worthwhile annealing schedules for this sort of thing were developed by Aussie Graham Stone in his book "The Schedules" which sadly is hopelessly unavailable.

I would suggest making the piece entirely from clear so you can see how effective the annealing cycle is. You want to see only black. Colors are very bad.

Big solids can be very scary. Last year Josh Simpson had a big planet blow on him simply trying to remove it from a kiln that had suffered a power failure. The six inch laceration on his leg took many many stitches and he didn't work for some time.

[Eben Horton]

The more you anneal it on the pipe makes a big difference too.. give it 4 or 5 deep flashes after your done makiing the thing.. a piece that goes in to the annealer that is at one even temp can be annealed a lot quicker than one that has different heats inside it.

[Monika Libor]

The only worthwhile annealing schedules for this sort of thing were developed by Aussie Graham Stone in his book "The Schedules" which sadly is hopelessly unavailable.



There is one on e-bay for sale:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120276979005

Monika

[Tom Fuhrman]

How do the Italians get by with annealing some of their larger sculptures in far less time than we normally feel is good? They've been doing this sort of thing for many years and seem to not have too many problems, or am I missing something. I've also seen the Czechs do the same on certain occasions.

[Jordan Kube]

I like to speculate that the convection in their gas annealers has something to do with it.

[Marty Kremer]

Cynthia (selling Stone on ebay) might cut you a deal if you email her and plead poverty and promise to send her a nice piece of glass too. Tell her that I'm the perp.
Or you could just ask for a schedule on Warmglass.com- any of us with Stone's book would be happy to share.

Josh had been used to getting away with annealing murder due to the spherical nature of most of his stuff. 100lbs just got away from him. Or else listening to the mechanical relays click on and off for 6 weeks did.

I'm working on some 3" thick Bullseye bowls. Bullseye recommends a 4 degree F drop per hour from 960 to 800 (it speeds up to 6 or 7 dph from 800 to 700!). I'm not going to argue.

[Pete VanderLaan]

There is one on e-bay for sale:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120276979005

Monika

************

I already have the book or I would be out bidding for this with price not being important. In my mind it is certainly more valuable than the Volf series.

[Brian Wong Shui]

I purchased a copy of Schedules last year from

Daniel Ablethorpe
ARTISAN BOOKS
159 Gertrude Street
Fitzroy Victoria 3065
AUSTRALIA
Phone: (03) 9416 4805
artisan@alphalink.com.au
www.artisan.com.au

For A$130 including shipping to the USA. You can E-mail Daniel to find out availability.

[Tim Bassett]

Graham Stone has told Daniel that he will be reprinting his book sometime in the future. As Graham self-publishes the book in small runs I believe that it will definitely be back on the market some time in the future.

[Travis Frink]

Thanks for the replies. I passed on the recommendation for longer time but the girl just said "That is not possible at THIS studio." She is gonna be coldworking these pieces before trying to sell them so she might find out soon enough if more annealing really was necessary. I am staying as far away from those things as possible cuz if one does go off it may rival one of her infamous rampages- and i want no part of either.

The mention about the Czechs and Talians annealing successfully(?) in shorter time was interesting. The annealer being used here is gas fired and has a belt or chain-driven ceiling fan inside so there is a lot of circulation. Is that gonna make a difference?

I am still curious if different compositions of soda glass need longer annealing time.

[Tim Bassett]

Graham Stone was one of my lecturers at university. He has an amazing amount of knowledge about annealing glass. Graham was always concerned about our annealing techniques in the hot shop but it is pertinent to point out that 100% of the work that my partner and I made at university is still in one piece...after six or seven years. We were told that sealed pieces made in the hotshop would never survive...most of us have experience with xmas decorations that are sealed and manage to survive quite nicely. I have recently been lampworking electrodes onto blown vessels where I get the base of the piece hot enough to lampwork and the rest of the piece is cold. it is not a fast process (takes five minutes or so) but it is the sort of thing that Graham has told me is impossible. I really think that kiln formers have a different knowledge than those of us that work with hot glass. I would use every bit of Grahams knowledge on annealing flat glass and for casting but the hot glass section would have all of us annealing paperwieghts for days....we know that that does not happen and most of us do not have customers complaining about things that break in sunlight etc.
I will try to attach a photo of a plasma piece that has a lampworked electrode onto a blown piece..(it was re-annealed)

[Rick Sherbert]

The book went for $200.

[Brian Blanthorn]

I have been helping a girl at the public studio here with some larger (by local strandards) solid pieces and it made me realize how little I know about annealing of larger work.

The pieces we are working on are between 3 and 5 inches in diameter and 18 to 15 inches tall- cylinderesque in shape. I dont know how much they weigh. The studio staff seem to think that the studio standard "overnight" annealing "in the back of the annealer" (it's a 4-foot-deep cave) is good enough. As i said, i know little on the subject but it seems short based on what i have seen at other studios (but they were using SP). Does anybody have any ideas on this?

Are there any general guidlines on how much annealing time is needed based on how thick or heavy the piece is?

Do different soda glasses (SP, Gaffer, spectrum....) have different annealing times?

Do inclusions of layers of metal foils and colors effect annealing requirements?

Thanks for your thought on this.
Travis


Much of this anealing lark is realy about treatment prior 2 aneal

Then correct aneal

Then probably more important is the cooling after aneal especially the later stages

Then U got inclusions n shape etc

Tell her that U have consulted experts who have been working some 20 / 40 years n they say injury / death is a definate probability with poor aneal on that scale and U want no part whatsever in this recless venture

From hot min 4 me if a "safe" peice be in kiln some min 3 days much of that is cooling after aneal, I always chop up my glass n poor hot wax on it n never had a problem

Grahams book is exelant on aneal n other stuff

Brian

[Pete VanderLaan]

Graham Stone was one of my lecturers at university. He has an amazing amount of knowledge about annealing glass. Graham was always concerned about our annealing techniques in the hot shop but it is pertinent to point out that 100% of the work that my partner and I made at university is still in one piece...after six or seven years. We were told that sealed pieces made in the hotshop would never survive...most of us have experience with xmas decorations that are sealed and manage to survive quite nicely. I have recently been lampworking electrodes onto blown vessels where I get the base of the piece hot enough to lampwork and the rest of the piece is cold. it is not a fast process (takes five minutes or so) but it is the sort of thing that Graham has told me is impossible. I really think that kiln formers have a different knowledge than those of us that work with hot glass. I would use every bit of Grahams knowledge on annealing flat glass and for casting but the hot glass section would have all of us annealing paperwieghts for days....we know that that does not happen and most of us do not have customers complaining about things that break in sunlight etc.
I will try to attach a photo of a plasma piece that has a lampworked electrode onto a blown piece..(it was re-annealed)
************

Glass has quite a memory. Whenever I read a post like this I am reminded of a very well known glass artist from the Smokey Mountains who had a particular series of work that all began to break up about seven years to the day after they were made.

[David Patchen]

I also lampworked a neon electrode to a piece blown with Spruce Pine cane and it worked just fine. The piece was just an experiment so I didn't bother to re-anneal the entire thing. The piece is still together and lights up just fine two years later.

I've found that even cylinder and tubular shapes are pretty strong and withstand stress nicely. A good example is heating cane--some people spend minutes warming it gently with a torch and baby it into the glory hole, but I've found if the cane is pulled well (hot, even, not shocked by hitting the ground, etc.) you can put a room-temp setup right into a ripping hot glory without a problem. Proof of the strength of a glass cylinder/tube. I always crack up when I see someone flaming a plate of cane for minutes before heating it. I don't do the same with twisty cane as I believe the stress isn't so even and it will sometimes crack if not warmed up prior to the glory.

[Zachary Jorgenson]

I always crack up when I see someone flaming a plate of cane for minutes before heating it.

At least now we know how to get a laugh out of you.

[Peter Bowles]

There are other reasons to pre-heat the cane before taking them to the glory hole - its not just about thermal shock. I always preheat canes in a kiln before moving them to the gh.

Peter

[Rick Sherbert]

Other than thermal shock, what are the reasons to pre-heat in a kiln? I can't think of one. If I could just chuck it in the glory without it all cracking, I wouldn't waste the time in the kiln.

[Jay Holden]

Steuben makes large solid pieces of the size she is making and uses a 48hr lehr then checks them for strain and re anneals them in a kiln for another 48 hours. Steuben glass is much more touchy than soda lime.
Jay.

[Peter Bowles]

Its subtle, yet there is a different depth of heat in canes that are preheated in a kiln. I have found with reticello that preheated canes take less time on the plate in the glory hole and thereby can maintain their integrity better. They will tack sooner and roll up and twist so much easier without canes dipping.

As I say, its subtle but noticeable - and if you have a single side firing burner (which I dont) the canes will have a much more distributed heat if they are preheated. If you are working with murrine, the preheat will help stop them balling up through surface tension so edges and patterns stay more defined.

I guess its just a personal thing, but it makes a difference to me and takes no extra effort.

Pete

[Rick Sherbert]

Got it Peter, thanks for explaining it.

Cheers

[David Patchen]

Agree w/Peter. I always go to 1000 with a plate of murrine for 45 min before picking it up. I also preheat pickups where there's mixed cane and murrine because of the murrine in them. Murrine is very cranky stuff and won't usually be happy without a soak in a kiln first.

But for making tumblers or anything else with just plain cane picked up on a bubble, or for making twisty cane, there's usually no need. I just began making a new series where I do an overlay then pick up cane on a bubble and it's super quick to just go right into the glory with the cane. Having a warm plate helps though so it doesn't become a heat sink.

[Travis Frink]

Steuben makes large solid pieces of the size she is making and uses a 48hr lehr then checks them for strain and re anneals them in a kiln for another 48 hours. Steuben glass is much more touchy than soda lime.
Jay.

is this to say that the pieces can be reannealed successfully in order to relieve strain that may have not been removed on the original annealing?

Are there precautions that should be taken when bringing the pieces up to annealing temp. again?

How long should the pieces be held at annealing temp to remove the strain?

How slowly should the pieces be cooled after dropping below annealing temp?

I think Brian B. and somebody else mentioned that how the piece is treated before annealing ("a few deep reheats in the glory") also makes a difference in annealing time. The pieces we are working are cooled over a period of 5 to 10+ minutes with multiple flashes in the glory till they reach a state hard enough that they don't change shape in the annealer after breaking off. Sometimes she even turns the piece on the pipe inside the annealer for a few minutes til the last traces of red glow are gone before breaking it off inside the annealer. Is this excessive? Does it change the time required for a proper anneal?

Sorry to keep throwing out questions but the more i learn, the more questions i come across. Thanks for all the great info.

[Jordan Kube]

When bringing a piece back up to temperature you can go as fast as the glass can handle. You're not annealing it on the way up you just don't want to break it.

Turning the pieces inside the annealer is the best way to do things. You can put it in hot and let it cool down to annealing temperature and there won't be any questions about treatment prior to going in the oven. Do you have a little opening in the side of the door or something? The Italians also do this with their thicker pieces. I suspect that helps with their annealing as well.

[Peter Bowles]

I sometimes switch the glory hole off and do several reheats as it cools down too, but cooling on the pipe inside the annealer sounds better.

We use electric annealers so it wont be so relevant here, but I'm also very careful about putting work too close to elements as the radiant heat can cause problems especially on heavier works.

For really thick work I will ramp and hold several times through the annealing range to allow things to even out before the next drop in temp. If the work is tall and thick I will certainly make the annealing curve longer to accommodate the difference in temp through the height of the kiln and the piece also. And for some strange, possibly mythological reason, I dont like to cold work anything thick for a few days either, there's no science that I know of to support this but it makes me happier.


Pete

[Brian Blanthorn]

I sometimes switch the glory hole off and do several reheats as it cools down too, but cooling on the pipe inside the annealer sounds better.

We use electric annealers so it wont be so relevant here, but I'm also very careful about putting work too close to elements as the radiant heat can cause problems especially on heavier works.

For really thick work I will ramp and hold several times through the annealing range to allow things to even out before the next drop in temp. If the work is tall and thick I will certainly make the annealing curve longer to accommodate the difference in temp through the height of the kiln and the piece also. And for some strange, possibly mythological reason, I dont like to cold work anything thick for a few days either, there's no science that I know of to support this but it makes me happier.


Pete

This is the way I c this anealing lark

Attainment of temp Evenivity n the maintainence of it through the cooling

Get the glass at an even temp above aneal then maintain this

With "normal" kiln working this is easier as U not got problems of vessils / stemware collapsing

4 the leir ( anealer) have it above aneal temp if poss then just put the work in when its "frozen" then at end of day have it then go through aneal
if its cold it will heat up if hot will cool it will achive evenivity quickly above aneal as its more soft at this temp it cannot B strained as its 2 soft ( liquid )
( ok its always a liquid anyway usualy unless U got some weird stuff in there )

My general personal aneal guide is

Generous above aneal skimp a bit on the aneal proper generous with the cooling specialy as room temp approaches

I am confident with my method as I saw, chisal n pour 60 / 80 deg c wax on all glass

This method gives me speed with caution my peices R roundish n in a mould if its thick / thin I go up an aneal thicness

I use Grahams schedules so usualy use the thinner one but add time eithere side of aneal

I make often 30 + kiloes one block peices + / -

Its actually difficult 2 heat large bits of glass from room temp as U got thermal shock + un even heat in kiln so this re aneal sounds a bit crazed why not aneal correctly in first place ??


Getting back to Travise s first Q

If this girls stuff does injur / kill somone some smart layer will go looking 4 somone 2 sue

So I would have a note prominately displayed signed by whoever is in charge saying that this leir cannot B used 4 work thicker than 2 inches or whatever


Brian

[Travis Frink]

This is the way I c this anealing lark



Getting back to Travise s first Q

If this girls stuff does injur / kill somone some smart layer will go looking 4 somone 2 sue

So I would have a note prominately displayed signed by whoever is in charge saying that this leir cannot B used 4 work thicker than 2 inches or whatever


Brian

Japanese lawyers and legal system are not as sue-happy as in other countries- thanks be for that. However, that may explain a LOT of the stupidty and feigned naievity that goes on around here. It still is funny to see how people jump when you say lawyer though- gets stuff done without a whole lot of B.S.ing

Maybe i will throw the L word in the next time i talk to her about getting the work annealed properly the first time.

Regarding the question about the "small door in the annealer": The annealer here is gas fired with a big 3'x3' door and a smaller 16"x16" that we usually just close down so there is only a small gap the width of the pipe as we turn the piece inside ther annealer. Break off when the glow is gone.