Hi All, sorry if this is a daft question, but can I just check I've interpreted something correctly. I've read about the annealing schedules and if I don't want to do batch annealing I think I get the kiln to the required temperature first and then keep it an the garaging temperature for as long as I'm making beads in that session (is this called garaging?) then when the last bead is made I then start the clock and the annealing programme begins. If this is right, does it matter how long the first bead is in there for e.g. if I am making beads for 4 hours, the first bead will have sat in the kiln for the 4 hours, can it be in the kiln (garaging ?) for too long before the annealing programme starts? Thanks.
Hi, that's correct!
Generally it won't matter hi on The first bead is in there. There are a few colours that don't like it, But not many And nothing for you to worry about just yet. X
My kiln is set to garage for 8 hours. I don't always let it go that long if I've finished working but quite often it goes the full time. Never had a problem.
Not a silly question at all. You can't over anneal glass but you can under anneal. So, you can have a garaging session of 4 hours or even 12 hours if you want and it won't matter that the first bead has been in there for all that time. However, you ought to make sure that the LAST bead gets a certain amount of time just sitting at the annealing temperature (which is around 520C for Effetre).
The amount of annealing time is dependent pretty much on the size of the bead. Anything under an inch in diameter needs around 30 mins just soaking at the annealing temp. However, something large - like a big paperweight will need many hours - or even days, to anneal. Small beads will need less. SO....
It's a good idea to make your biggest beads first and finish up on smaller beads in a garaging session.
When the last bead in has had it's soak at the anneal temp then you can start to allow the kiln to drop in temp. This is usually at a rate of around 60C/hour, until you get down below the "strain point" of the glass (which is when molecular movement has pretty much ceased.) For Effetre, this is around 449C, so the critical bit is to cool at 60C/min from 520C to approx 400C. After that you can in fact increase the rate of cooling a little to get back down to room temperature. I actually cool very slowly to 250C (just to be on the safe side) and then I turn off the kiln, although I leave the doors closed so that the kiln will get back to room temperature by "natural" heat loss.
Sal is invariably correct on these matters. For what it's worth, I programme my Kiln to garage at 500c for 12 hours (not that I torch for 12 hours at a time ) when I've had enough I skip to the next segment which takes it up to annealing temp, and stays there for 30 minutes and so on. It works for me. Since using a working schedule I've not had any bead casualties.
Yes you certainly can't over anneal.
I only batch anneal and there are times when I have totally forgot to nudge the kiln to ramp down and woke up in the morning shouting ohh I need to ramp the kiln down.
The only damage is hubby whining at mean because I have used more electric than I should have done.
You'll find more info here on the Frit Wiki
http://www.frit-happens.co.uk/wiki/Annealing#Annealing
;D
Thanks for all your replies. I'm not sure what I would do without this site, so much information and so many helpful and friendly people :)