Batch annealing schedule - moretti glass beads in an SC2.

[Lee - Kilncare]

Is that the kiln you have had bought or one you think is better than yours?

[lyzzydee]

Is that the kiln you have had bought or one you think is better than yours?

Hello missed your reply!! My friends have bought me that kiln, I have done a few bits in it manly PMC I am not sure it gets hot enough to anneal glass.

[lyzzydee]

Well I took the plunge and bought myself a paragon sc with bead door kiln. I am so confused, I have read the manual and I simply don't get what it means, I am going to read this thread and attempt the first trial run. Its really scary as the most prominant part of the instructions is all about how dangerous it is!!!

[awrylemming]

I have the same kiln - it took me six months and the purchase of a metal table before I felt brave enough to use it.  And I feel proper daft about it now    If it really worries you, I bought my table at Ikea, it was only about £30 and has some handy shelving too.

[lyzzydee]

I have thrown caution to the wind and I have hoovered it out and put it on a test firing, I have followed the instructions given on here earlier in the thread. Ceramic tiles are my friends, I have a load left over from my kitchen floor revamp, so I have stood the kiln on double thickness ceramic tiles!! now trying to become acustomed to the clicking it makes heating up!!

[Trudi]

Good luck, you'll soon ignore the clicks

[lyzzydee]

Well that has gone off with no problems. I picked spd3 as suggested earlier in the thread and the temp on there says single speed 3/ 1000f/555c rate per hour in the booklett. So I was expecting it to go to 555c and then stop heating. It eventually reached the completed beeping at 600c.

So is that something I should be aware of??

[Blue Box Studio]

My SC2 overshoots if I use 'full' in the programme so I just come down a few degrees instead and it works fine.  Someone else mentioned this on the forum as a workaround and it seems to work.  Mine sits on a slate tile and aheat resistant sheet I had when  I did a lot of soldering, that seems to keep the heat off the worktop underneath.  I fire overnight so the clicking doesn't bother me, but might scare off a few hedgehogs at the end of the garden I suppose.

[Madam Steph]

Thanks to everyone that contributed to this thread. It's been very useful for me this weekend.
SC2 arrived on Thursday and I empty fired it Friday and did my batch annealing of beads already made last week and both pairs (my first ever) at Flame Off, 9 April.
Happy to say that all went well with no casualties.
I did my first 'hot bead' firing tonight through the bead door, and the first bead in must have been quite heavy. I did wait utill it had lost its glow, but when I took all the beads out, this one must still have been too hot. At first I thought it has cracked and broken, but on closer inspection, it was flat, so more cooling time for big beads before they go in. I made quite a few spacers to go with 2 sets I have already made, and apart from the flattened one, 2 other larger beads for the other set. These were both ok, but, c'est la vie!
Will have to wait now till my batch of orange effetre arrives to complete one of the sets, and must also get on to Warm glass, as the small square of fibre board they sent with my kiln was broken when I removed it from the cardboard 'sandwich'.
I patched the board together today for my firing, but as a bead shelf came with it, can I use that while I'm waiting to contact Warm Glass, or in fact can i use it anyway?
I will put up some pics of my first beads fully annealed tomorrow, but meanwhile, here is my completed Loungio

[Trudi]

I have half a rod rest inside my kiln that I use to rest the mandrels on for new beads. And after they've been in there a while and have firmed up, I move them along and stack them!

[lyzzydee]

Thanks for all the help, I have got up early this morning and set off my kiln on a batch annealing run, It took me a few times to get it set up because once I lost where I was and while I was trying to figure that out it bounced me back to the beginnng!! But its clicking away now.

Thank goodness I bought a kiln that everyone seems to have!!!

[Madam Steph]

I have half a rod rest inside my kiln that I use to rest the mandrels on for new beads. And after they've been in there a while and have firmed up, I move them along and stack them!

Thanks, Trudi. It makes sense to keep them off a surface at first, I guess

[Martman]

Helen

Can you tell me where you got the information from or how you came up with the schedule, its nothing like the manual?

Do you or any one else reading know where I can find the facts, what is the science behind the annealing process?


Mart

Hi guys,

This is the the schedule I use for batch annealing my beads in my SC2 kiln.? I cool my beads in vermiculite straight from the flame, then take them off the mandrels when cold (leaving the bead release on), and make bead kebabs on old mandrels cut down to fit in my kiln.? Make sure the beads aren't touching, just in case the glass gets tacky and sticks together whilst annealing.? I place a piece of fibre board on the floor of my kiln to protect it from any mishaps, then I either support the kebabs on kiln shelf posts or use a steel wire mesh cradle to hold the mandrels.? I got the steel mesh from B+Q, and cut and bent it to fit inside my kiln.? There are many other ways of doing this, these are just the ways I've tried.

Anyway, here's the schedule:

PRO1 (or another free slot)
Ramp1 149C
Temp1 520C
Hold1 60mins
Ramp2 50C
Temp2 371C
Hold2 0000mins
Ramp3 0000

It's basically the schedule Lorna (Pixiewillow - thanks again Lorna ) posted on GH a while ago, with a longer hold at 520C that will anneal beads up to about an inch in size.? If you are wanting to batch anneal larger beads, you will want to add more time to this hold segment to allow the glass stresses to be fully evened out before cooling.

Here are the kebab images - 1. kiln shelf post set up:



2. Wire mesh cradle set up:


If anyone has any other suggestions or schedules, please feel free to add them.

Cheers! ? HP x

[Redhotsal]

Try the Wiki first.....http://www.frit-happens.co.uk/wiki/Annealing

Then you might want to do a search on the general forum using "annealing" as a possible search word.

Not trying to give you short shrift but a search will reveal LOTS of information which has already been written about annealing so there's little point in writing it all again.

The Paragon kiln is a general kiln - it wasn't made with annealing beads in mind, particularly, so why should the manual (which I've never seen) be any more accurate than a forum dedicated to bead making?

In a nutshell annealing is the process which eradicates mechanical stress within your glass which is caused by the glass cooling too quickly. Glass is a good thermal insulator so a hot bead tends to cool too quickly on the outside while the inside is still too hot. The outside contracts around the hotter expanded inside and mechanical stress is introduced. You can see this stress in transparent glass with polarising filters. It's basically where the molecules of glass have bunched up more resulting in a slightly higher refractive index to the material. This shows up as dark lines on a polariser. This is usually where the glass fractures. It is a weak point in the glass.

Annealing takes the glass up to a temperature where molecular movement starts and if you bathe glass at this temperature for sufficient time it gives the molecules enough opportunity to basically go to an equilibrium - i.e. there is no stress. It is then CRITICAL that you cool the glass in such a way that the outside and the inside cool at the same rate.  For normal beads this usually means a drop in temperature at a rate of 60C/hour or thereabouts. For big lumps of glass this rate is slower because you have to give the glass time for the heat to perculate through. Therefore - some big glass pieces like paperweights or cast pieces need to be annealed for DAYS not hours, like beads.

For Effetre a reasonable anneal temperature is 520C though this is different for different types of glass. Lauscha, for example needs a higher temperature. There is a point where molecular movement is slow enough not to make a difference to the stress. This is called the strain point and for Effetre this is around 549C. Under this temperature, you've basically "locked" any stress in. So you need to go above the strain point to successfully anneal.. The anneal temperature is much lower than the temperature needed to actually melt the glass so annealing should never slump the glass, merely change its molecular structure, so to speak.

That's a little simplistic - but for our purposes it's probably good enough. So, there is no specific annealing schedule - it's really dependent on the glass you use, the size and shape of the object you want to anneal and whether you batch anneal a cold piece of glass or hot anneal an already hot piece.

Bit like how long is a piece of string.

And "annealing bubbles" do NOT anneal glass - they merely slow down the rate of cooling. They're handy for objects which are to be annealed later but the temperature drop in annealing bubbles is usually too quick and stress is almost certainly introduced into all but very small and very thin pieces, thus necessitating annealing (batch annealing) at a later date. It is preferable to put your hot bead into a hot kiln and hold it there until you begin the cooling process. You cannot over anneal a bead but you can certainly under anneal a bead.

Hope this helps. Going to bed.   

[Magpie]

For big lumps of glass this rate is slower because you have to give the glass time for the heat to perculate through. Therefore - some big glass pieces like paperweights or cast pieces need to be annealed for DAYS not hours, like beads.

If you go to the observatory at Herstmonceaux, East (?) Sussex they have on display a lens from a massive telescope, a bit cracked and battered now, but they cooled it over a period of 9 MONTHS!