Slumping Bottles

Slumping bottles in your kiln is pretty simple and straight forward.

Bottles come in a variety of shapes, sizes and colors.

Make sure the one you have selected will fit inside your kiln before beginning.

These pieces make great spoon rests, cheese servers, wind chimes, and many other creative projects.

These wine bottle cheese plates are usually a hot item at craft shows.

Another fantastic idea for a hot seller is to obtain small vials or perfume bottles, and slump them flat inside the kiln.

Attach them to a necklace that can be worn around your neck.

Some individuals try melting colored glass inside the clear bottles.

This usually doesn’t work because of the difference in the COE of the glass in the bottle and the colored glass.

Even if the process appears to be successful after firing, there is no way to fuse different COE glass without achieving stress in the glass.

Although the process of slumping bottles is not difficult, it does require time and patience.

Be prepared to spend some time on this project.

To proceed with this process, you need a basic knowledge of your individual kiln and an understanding of:

  • Annealing procedure
  • Avoiding devitrification
  • Preventing thermal shock

  • The process of slumping bottles is quite simple and requires only a few items.

    slumping bottles


  • Empty bottle
  • Soap and water
  • Prepared kiln shelf or shelf paper
  • Kiln
  • You will first need to clean your bottle.

    Remove any labels and wash thoroughly.

    Allow the bottle to dry completely. This may take time, because of the shape of the bottle.

    You can apply a devit spray to the bottle to prevent devitrification during the process. This is especially recommended for bottles that have any color.

    slumping bottles

    You will need to place your bottle on a prepared kiln shelf.

    You can prepare your shelf with either kiln wash or kiln paper. This will keep the bottle from sticking to the shelf.

    Place your bottle on the kiln shelf. There are molds that can be used to slump bottles, but they are not necessary, because bottles can just be slumped on the kiln shelf.

    If you are planning on hanging your slumped bottle, bend and place a 20 gauge copper wire inside the neck of the bottle. This will allow the glass to slump around the wire securing it in place.

    slumping bottles, slumping glass bottles

    Now turn on your kiln and allow it to slowly warm up.

    You should be increasing your temperature at around 500 degrees Fahrenheit per hour.

    You are in danger of thermal shock if your increase your temperature much higher than this rate.

    When you reach 1100 degrees Fahrenheit, soak your bottle for about 10 minutes.

    Soaking the bottle will allow all of the glass to reach the same temperature.

    Keep warming up your glass at about 250 degrees per hour until you reach 1300 degrees Fahrenheit.

    Once you reach this temperature, you can heat

    slumping bottles

    up the piece as fast as you want until you reach about 1425 degrees Fahrenheit, or until your bottle has slumped to your desired shape.

    You now want to crash cool the kiln to about 1100 degrees Fahrenheit.

    This can be accomplished by cracking open the lid of your kiln slightly.

    This will help prevent devitrification.

    To anneal your bottle, you can simply turn off the kiln and allow it to cool naturally.

    You want the piece to cool down at about a rate of 150 degrees per hour.

    slumping bottles

    The side of the glass that is exposed to the air and heat will have a graceful slump and will be glossier than the other side.

    Your piece is complete and ready to become whatever you desire.

    Remember that glass can obtain devit very easily, which can result in the glass taking on a matte finish.

    So carefully watch your firing procedure and take notes.

    You can apply a devit spray before firing to help prevent devitrification, but this is usually only recommended for colored glass bottles.

    slumping bottles

    The firing schedule should be modified and tested for your kiln. Each kiln is unique and reacts differently.

    Keep good accurate notes of your slumping bottles. These notes will really come in handy for future firings.

    Try different types of bottles for slumping bottles; such as wine bottles, beer bottles, perfume bottles, etc.

    Make sure that the bottle will fit inside your kiln with enough room around it for air circulation.

    Once you have flattened your bottle, you can slump these glass bottles into spoon molds.

    These make wonderful gifts and sale items at craft fairs.

    This is a small video of slumping glass bottles inside a kiln.

    It is currently at 1325 degrees Fahrenheit.

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