 bullseyeglass.com • View topic - calculating glass

# calculating glass

For discussion of processes related to using Bullseye glass, including kilnforming and kilncasting, torchwork, blowing and stained glass.

## calculating glass

I know that you can calculate glass amounts when casting by multiplying the water weight by 2.6, but was wondering if there is a way of calculating by using the weight of the wax? Does it make a difference if you are using powder or billets? (I'm primarily doing open-faced pate de verre)
nanK

Posts: 2
Joined: Thu Aug 26, 2010 10:56 am

## Re: calculating glass

I don't know what units you are measuring in, but use of the metric system makes it all much simpler. If you measure the volume of water in metric you can apply the 2.5 or 2.6 specific gravity multiplier directly. [the specific gravity takes water as 1]
So you need to find the specific gravity of the wax and set up the equation to determine the volume of water that weight would equal and then multiply by the specific gravity of glass.
Glass is glass what ever form it is in. So soda lime glass [waht we use] has a specific gravity in the region of 2.5. Lead crystal and casting glasses have different S.G.s. Whether the glass is in a big chunk or powder determines their prefired volume [you will find the same weight of powder takes up more volume becasuse of the air spaces, than a single block of glass of the same weight.]
Stephen Richard

Posts: 224
Joined: Mon Jan 25, 2010 9:02 am

## Re: calculating glass

With wax I put the wax in a vessel of water and mark the displacement level then remove the wax and add glass until the water line reaches the same displacement line. Then add a bit more glass.
Jerry Jensen

## Re: calculating glass

Microcrystalline wax has same specific gravity(weight for a given volume) as water.
Weigh your wax item(grams will be easier) by 2.6 for soda lime glass( all the common fusing glasses of 90 & 96 COE)and that is your glass needed.
edwardcantarella

Posts: 11
Joined: Mon Nov 27, 2017 7:38 am 