Annealing Bullseye and Oceanside Together

Credit: Bullseye FAQ_kilnforming_annealing

The question sometimes arises as to whether Bullseye and Oceanside can be annealed in the same firing, since the two glasses cannot be combined in the same piece.  They also have different published annealing soak temperatures (also known as the annealing point).  The explanation requires some knowledge of annealing.

Annealing can be done at other than the annealing point. This is because annealing can be done over a range rather than being a single magic figure. Bullseye did not change their glass when they altered the recommended anneal temperature.  This means that the annealing point is still at 516°C. Their research has shown that good annealing results are obtained by doing the temperature equalisation soak at the lower end of the range.  Temperature equalisation throughout the piece is what happens during the annealing soak. Therefore, it is a descriptive term for what happens at the annealing temperature.

Bullseye's previous annealing temperature was 516°C and Spectrum's was/is 510°C. These are very close, and in the past, many chose to anneal at either - or in most cases, both - of these temperatures. Bullseye's research has shown doing the temperature equalisation at the lower end of the annealing range provides good results and ones that are more reliable than the higher temperature.  This research is applicable to all soda lime glasses, not just Bullseye. Therefore, the same principles can be applied to Oceanside fusing compatible glass, or any other fusing compatible glass. This further indicates that you can anneal both Bullseye and Oceanside fusing compatible glasses at the same temperature. 

Further support to this view of the possibility of annealing the two glasses at the same time and temperature is given by Wissmach.  Wissmach W90 and W96 now are both given the annealing temperature soak as 482°C.  Previously they both had been at 510°C.

If you feel the need to compensate for the annealing point differences, you can increase the 482°C for Bullseye by 6°C to 488°C for both. Although I don't think it is necessary, 488°C will be fine for Bullseye and safe for Oceanside.