Bullseye glass question

[noora]

Here is a useful chart  ................   http://www.bullseyeglass.com/methods-ideas/glass-reactivity-chart.html

Thanks! That's great, I should print it and put it on the wall 

[Krysia@No98]

I have used it to make some murrini to put in a fused piece, but I haven't used it other than that,

Me too.  I tend not to use it that much as I can't mix it with the other glass.  I bought the stuff I have for a particular fusing project and it is much more expensive then 104.

But it is good when you are fusing and you want to make your own stringer and bits and pieces in your fused work.  And there are far more reasonably priced bullseye colours then those compatible for float.  I will be branching into float this year.  You can use small amounts of bullseye frit with your 104.

[Dietmar]

I did some research on the lead topc with Bullseye Glass. There are few colors with lead, most of them are the gold rubies (pink, cranberry, purple) plus the old black and dense white. They reworked the black and removed the lead from the recipy.

A qualitative test for lead in the glass:
Grind about 20-50mg og the glass in a ceramic mortar and mix the powder with 300-600mg of a 50/50 soda potash mix*. Take a 20cm length of a 1mm stainess steel wire and bend one end into a 5mm ring. Herat this ring to visible glow in the end of an oxidizing flame and dip it into the powder mix. Melt the powder and dip the ring again into the powder, continue untill all powder is molten. The melting process is done once you see the molten powder nicely flow on the ring. Let the molten sample drip into the mortar and grind it into a powder. Leach the powder with three portions of water and discard the extracts. Leach the remaining solids with 5ml of 5% acetic acid and put the extract into a test tube. Add one drop of a 2% solution of poiassium chromate. If there is lead in the glass there will be a precipitation of yellow lead chromate.
* = If you have just one of both chemicals use it for the whole amount. The analysis will not be affected by this fact. The mixture is just for a lower melting point.

Quantitative detection of lead:
For this analysis I leached cut, cleaned and measured pices of the lead bearing glasses with 5% acetic acid for 24h at room temperature. The original detection was per atom absorption spectroscopy. For an estimation I added potassium chromate solution to the sample. Samples with safe (low enough to be tolerable) concentrations of lead did not show precipitation of lead chromate.


Qualitative setection of cadmium:
The sample preparation (grinding an melting with soda potash mix) is performed as done for the lead test. Put about 50mg of the powderd sample into a small test tube (7*70mm borosilicate glass) and add the same amount of sodium oxalate. Heat the bottom of the test tube to a nice glow in a well ventilated place. If you see a dark metallic mirror on the colder parts of the tube add a small amount (5-10mg) of sulfur and heat the tube again. The mirror should turn orange or yellow if cadmium is present.

Discard all leftovers with lead, chromate or cadmium as chemical waste with heavy metals in accordance with the local regulations.


I recommend to cap the blanks for plates or dishes with a thin layer of clear glass, if the lead and/or cadmium bearing colors are used in the design.