Bottle slump mishap

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    Terri C

         I slumped three blue beer bottles in a small botter slumper made for three bottles. The schedule was:

    Seg 1       Rate 325 f Hr     Target 1000     Hold 10 min

    Seg 2               600f Hr                 1480            15

    Seg 3               9999                     960              90 min

    Seg 4                   75                     400              10

    I wish I could post a pic but Ill try to explain what it looks like.  The bottom part of the bottles fused together the neck parts did not.  The outside body of the bottles pooled into the bottom of the mold.

    Im thinking the temp was too high or the hold times too long or both.  I was following a schedule I found in a book.  Can someone tell me what I did wrong and a better schedule to go by.  They are really pretty blue bottles, you know the ones from Budwieser Platnium.

    Thank you



    Since we don’t know what the mold looks like, or the results, it is hard to say. However, maybe you would have better luck prefiring the bottles flat.

    Dana W.

    Jester’s Baubles Fused Glass Designs


    I agree with Terri in that you may acheve a better result if you “flatten” the bottle with heat before a slump firing.  The temperature you listed in your firing schedule is sufficient to flatten it, but lengthen the time of the hold (by 5-10 mins depending on your kiln). Each kiln is different, so test fire & take notes.  Use the schedule that produces the best results for your aesthetic.

    Your slumping temp doesn’t nearly have to be that high.  Depending on your glass properties & size, your slumping temperature should be  around 1200-1300 degrees and held for about 20 mins.  Don’t foget to kiln wash your molds.

    Terri C

    Thanks for your comments.  Ill have to set up a picture site so I can share the photo.  Ill try the flattening the bottle first then slumping.  The mold I used was the common one for three small bottles used to make a three dip server.  I dont understand why molds and castings dont come with fire schedules and fill amounts.  Well Im off to empty those blue beer bottles, lol just kidding I dont even drink so Ill have to hit up my friends who do.


    I have a small kiln and have not slumped whole bottles but I have made many vases from parts of wine bottles which you can see of my FB page.  On the one hand, devit is likely so firing too slow is a problem but on the other, bottle glass is very stiff and cannot be fired too quickly. has a lot of information about working with bottles and I also learned a lot from Boyce Lundstum’s book “The Best Bottle Book Ever”.  I coat my bottles with Solution A to prevent Devit and fire slower than your schedule, using 8 segments to ‘stair step’ up to fusing temp. I would divide segments 1 and 2 each into two segments and slow down the kiln once the glass is outside the devit zone. I believe your segment 3 temp should be around 1030 degrees for annealing.  Unfortunately bottles are very unpredictable so if you want to experiment, try to gather a bunch of the same bottles.

    I would avoid fusing and slumping separately as the glass gets stiffer with each firing, also devit is more likely.  Sometimes two firings are necessary for certain projects but you should be able to slump a bottle into a mold in one firing.

    Flee at webetilin’ Studios

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