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    Porcelaine firing time VS zirconia frame size

    Discussion in 'Porcelain' started by Dali k, Oct 26, 2017.

    1. Dali k
      Fine

      Dali k Member Full Member

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      How do you guys calculate your firing programe lenth for porcelaine over zirconia when dealing with bigger zirconia sub-structures? We end up having very long firing programmes, I wonder if its not too much... What are your formulas or ways to calculate the hold and cooling time?



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      Last edited: Oct 26, 2017
    2. Contraluz

      Contraluz Active Member Full Member

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      In the 'battle' of pfm vs. zr, the long firing cycles is one of the drawback... I don't think there is a 'formula'. I increase about 10 degrees celsius for bigger frames and add holding time. But slow cooking and long time cooling is equally important!

      M
       
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    3. PDC

      PDC Active Member Full Member

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      My furnace has 2 selectable cooling positions and will hold the crowns at those positions until temps drop back to entry level. Heat rise rates around 40-45C/min. Hold time for 1 minute at top temp.
      Yes, it is a long cycle but a necessary one.
       
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    4. Sda36

      Sda36 Active Member Full Member

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      I would suggest even a bit longer, 25-30°/min rise, 2 min hold at high temp. Then a Really slow cool to room temp if we're talking the really big bridges.

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