Fused Glass Pot Melt Technique – Lessons Learned

pot melt on shelfIf you fuse glass, at some point you read about the pot melt or aperture pour technique. It is often talked about as a great way to use leftover pieces of glass or as a way to recycle a failed project. This technique has been on my “to-try” list for a long time.

The basic process involves suspending a clay pot with a hole, or multiple holes, in the bottom of it over a kiln shelf. The kiln is heated up to 1700 degrees F at which point the glass begins to flow out of the holes onto the kiln shelf creating, hopefully, a wonderful piece of swirled glass. At least that is the theory.

I read everything I could find in my books and on the internet about this technique and finally gave it a try. I was really quite nervous about it. For one thing, the last time I did a similar technique, a screen melt, it ruined my kiln shelf. My other concern was taking the kiln up to its maximum temperature of 1700 degrees F. I had visions of the clay pot exploding and ruining my kiln. The good news is that the pot did not explode, but the kiln shelf did take a bit of a beating. Here is a summary of what I did and what I would change the next time.

Potpot melt-2

I used a clay pot from Germany. Numerous articles I read said to use pots from Germany, Italy, or the U.S. because the ones from Mexico tend to crack. I made the hole in the bottom larger by chiseling away at it with a screwdriver and hammer. Not elegant, but it worked. The pot did survive with no cracks.

Glass

I used approximately 46 ounces of glass which resulted in an 11.5” disk. Almost half of that was clear glass. The rest was made up of mostly equal parts of blue and white and a few pieces of yellow/green thrown in. I placed them standing up in the pot grouping the colors together and added a lot of clear on top. I should have taken a picture of the setup. I ended up with a brown center. Not sure what happened, but next time, I’d use less glass and not pile up the clear on top.

Kiln Shelf

pot melt empty

I used an old kiln shelf with at least 20 coats of primer. Even with 20 coats, it roughed up parts of the shelf. I had to do a little sanding to get it smooth again. Next time I may try using a fiber paper on the shelf.

Firing Schedule

I went up to 1650 and held at that temperature for 90 minutes. That seemed like it was more than enough to empty the pot.  Next time I will only go up to 1600 and try a 60 minute hold. Then I dropped the temperature to 1480 and held for 10 minutes to let everything even out. It was pretty flat, but next time I would hold for 15 minutes.

All in all, it turned out okay. With this technique, it is hard to predict what the outcome will be. Some glass colors can change at high temperatures and some will react with others. I am not really fond of the piece as a whole, but small sections of it incorporated into a larger piece will make a great piece.

pot melt disk

6 thoughts on “Fused Glass Pot Melt Technique – Lessons Learned

  1. Teresa Antosyn says:

    Hi Margot, I have done some pot melts and find that using the terracotta trays that fit under the pots work great to use for the glass to melt into. That way I don’t have to worry about my glass shelves. I do plenty of layers of kiln wash, but about 6 or 7 layers and I can re-use these trays several time as long as I scrape and re-apply kiln wash so the cost is relatively low as opposed to having to replace my kiln shelves. Teresa

    • Margot says:

      I actually purchased a large terracotta tray for exactly that purpose. I have it kiln washed and ready to go, but just haven’t had the time to do another pot melt yet! Glad to hear that it works!

  2. Josephine McVean says:

    Hello, I protected my terracotta tray with 6 layers of kiln wash but it didn’t really stick on the sides every time I put a new layer on the sides a bit of the kiln wash came back off.
    So its out of the kiln this morning but the sides from the terracotta tray are stuck to some places of the glass.
    And its a pitty because the combination of the colours of the glass where beautiful.
    Does anyone please have a solution for this, I love the pot melt idea but don’t know exactly how to solve this problem.

    Josephine

    • Margot says:

      Josephine – My guess is the terracotta, unintentionally, had some sort of sealer on it that prevented the kiln wash from adhering to it in that spot. Two thoughts for the next time. If the kiln wash doesn’t stick, I would try heating up the tray to 1500 degrees F at 300 degrees/hour to see if it burns off what ever is on the pot. If it still doesn’t take the kiln wash, maybe a light sandblasting. Or, just try another tray.

      You can salvage your piece by using a tile saw to cut off the areas where the pot is stuck. In my experience, pot melts usually need to be refired. Sometimes I cut them to use the pieces as design elements, or I add to it to get the size/shape I want. Here are some pictures. On the bowl I added glass around the melt and then slumped it into a wavy mold. In the other picture you can see where I incorporated a small piece of the pot melt as a focal point.

      Pot Melt Pot Melt Element

  3. Norma says:

    Does anyone have tips for coldworking the back side of a pot melt. I use hand pads and grit for slurries. I still cannot get a “clean” backside form either kiln wash or Bullseye paper or papyrus

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