Tack fusing a tall stack

[rfreedfl]

I want to make candlesticks. I have fired multiple 2 layer pieces and want to stack them (staggered) and tack fuse them. Is this possible? If so, should they all be fired at once? Would I be better off gluing them or is there an alternate method to stack and attach them that someone could suggest?
Thanks,
Roberta

[Morganica]

It's certainly possible. Just make sure your annealing schedule is suited to tack-fusing--use a schedule intended for a piece 2-4 times as thick as the actual thickness of your stacked glass.

So, if you are stacking 3 pieces of 2-layer fused glass, instead of following the schedule for a 6-layer (18 mm or about 3/4 inch), you will anneal as if it's 1.5 to 3 inches thick. In general, your final schedule depends on how close you get to a full fuse--the more separate and sharp-edged the layers, the longer the anneal.

[Bert Weiss]

It is all possible. Cynthia gives good advice.

You need to understand that annealing is both terribly simple and impossibly complex. Glass anneals in 15 seconds, when the entire mass of glass is inside the annealing range and is within a temperature differential of 5ºC. This is the imperative that we spend hours accomplishing. First, the heat has to go through the thickness of the glass. Stacking the glass vertically is different from stacking glass horizontally, only in that horizontally there is more surface area in contact with a shelf. We have observed that glass that is fully fused is easier to anneal than when tack fused. This is because of the way that heat is transferred when there is less than intimate contact.

Typically glass blowers anneal much faster than fusers. This is because so little of their glass surface is in contact with the shelf. Most of the glass is open to the air, and can equalize temperature with the air much quicker.

If you are devising a schedule for a vertical cast piece, inside a mold, you calculate for the thickness of the glass and mold. Essentially you can do the same, compensating for the tack fuse effect.

What makes annealing so complicated is that we are controlling the air and guessing what is happening inside the glass. There are so many variables that nobody can tell you exactly how to do it, with surety.