Annealing for a piece done over many days
 

Hi, there! I'm still learning my basics at the torch and I'm trying to make a sculptural piece and it's taking me a few days to finish. In my last few attempts, by the third day, the piece keeps cracking while I'm trying to work it (even though I first warm the area at the tip of the flame) and I have to give up. :(
Do I need to anneal it at the end of each day or is it ok to anneal it when the piece is finally over?
I don't have my own kiln and need to go to a nearby workshop for annealing. Can I flame anneal my work at the end of each day and then do a final kiln annealing at the end?
Is it ok to put a cool piece into the kiln directly at the temperature of 1050 f?
Finally, I'm really scared that after making my piece and I put it into the kiln to anneal it may crack in the kiln.. how often does that happen? I make sure there are no visable cracks while putting it in.
Thanks in advance!

I too am still learning and I'm sure someone will correct and add to this post. I use a fiber blanket to slowly cool bead until I can anneal (in batches) sometimes 3 or 4 days. I know you can't put a cold bead in a hot kiln. Bead must be brought up to temp with the kiln. I have a small bead heater that brings the temp of beads and rods up to 800 degrees F. I've had a number of beads crack in the kiln with stress cracks that were not there or visible when I put in the kiln. Others will pipe in but I wanted to see how accurate my answers are. If I spent that much time working on a piece I too would be "scared to death" something would happen to ruin it. :waving:

Oops, I went into the wrong room. I work with soft glass. Don't know anything about Boro. I will be interested in the answers you get. Sorry about that. I shouldn't answer so late at night when I'm tired.

Pieces that take that long really require that you have your own kiln. You need to place the piece in the kiln at the end of each session to anneal, then you need to bring it back up to temp, slowly in the kiln before you continue to work on it, with frequent returns to the kiln to even out the heat.

hmmmmmmmmmmmmmmmm.... you have asked many questions grasshopper.... first... I would not put a cold sculpture into an already hot oven... thermal shock, sort of like pouring hot water on an ice cube.

the rest of the questions can have very fuzzy answers,, because it all depends...

the thickness of the work is a big factor. if its thick it needs to be annealed and or garaged before working on it again. but on the other hand....things that are thin I dont bother to anneal or garage before beginning work again. But.. I have also been doing glass many years and know my seals are good and everything is well warmed in the flame.

glass is a wicked mistress.... so yes you can put something in the kiln and it will still crack. It could be from questionable seals, incompatability of color, thermal shock, lots of stored stress in the glass that decides to let go at that moment because it can.

if you are flame annealing till you can get to a kiln... turn your gas way up and soot up the glass until its black all over, then turn up the oxy and gradually heat the glass till all of the soot is gone. then place it in a rack to air cool touching NOTHING. keep it out of a draft as well.


my best advice is, dont make larger thicker work without a kiln handy

Thanks guys for the all the advice! For now I'm spending a lot of time healing cracks as I go along. I've learnt the hard way that a neglected crack can destroy my piece.... but it really takes a lot of time!