Glass is a mixture of several compounds and elements. It contains silicon dioxide, calcium, potassium, boron dioxide, and other trace elements such as chromium and barium.
Most glassware tends to start melting between 1400 to 1600 F (760 C to 871 C). However, some specialized glasses can start melting at approximately 900 F (482 C). If you wish to obtain optimal glassblowing results, it would be best to use a kiln.
Glassblowing started in Mesopotamia about 40 centuries ago. Many historians believe this practice began as an accidental by-product process in copper smelting, and people adopted it because it produced shiny decorative products.
If you are a skilled glassblower, you can manipulate glass into numerous shapes and designs. Glassblowing is a scientific expression of art that requires an expert who understands the chemical and physical properties of elements and how to manipulate these properties to get a desirable product.
Although some glassblowers only use conventional blow torches, such instruments can only reach a temperature of 900 F, which may not be sufficient when melting raw materials. Sometimes you may need to go up to 1900 F (1037 C), particularly when blowing decorative glass.
How Temperatures Vary During The Glass Blowing Process
It crucial to note that glassblowers fluctuate temperatures when making glass. Here is a comprehensive look at the glass blowing process and how heating varies in this process.
- 1. The first step in any glassblowing procedure is identifying appropriate instruments and equipment. The equipment needed includes glass raw materials (sand limestone and soda ash), curable and glory hole furnaces, a blowpipe, crucible, a flat slab (marver), a kiln, protective gear, and steel tweezers.
- 2. Begin by wearing your protective gear, place the raw materials in a crucible, and heat it to approximately 2912 F (1600 C). This process converts the raw materials into a molten state forms glass once it cools down.
- 3. Allow the molten mixture to homogenize and carefully stir it to avoid bubbles. At this stage, you should lower the furnace’s temperature to about 2552 F (1400 C). Take the blowpipe and carefully gather molten glass from the crucible using one end.
- 4. Place the molten over the marver and roll it continuously using the blowpipe while ensuring the glassware gets a cylindrical and symmetrical design. During this phase, the glass should have a bright orange appearance.
- 5. If the glass begins to cool down, carefully reheat it within the glory hole furnace. The glory hole furnace should have an optimal working temperature of 2250 F (1232 C). When reheating this glass, it would be best to spin the blowpipe to ensure even heating.
- 6. Afterward, resume shaping your glassware on the marver and return to the glory hole furnace when the glass starts to cool and lose its bright orange color. This step is a repeated procedure as you will need to keep the glass’s temperature above 1000 F (537 C) during glassblowing and shaping. As you continuously heat and shape the glassware, you will need to hold the blowpipe with one hand while using steel tweezers on the other hand. This step requires perfect hand coordination to ensure you get a desirable glass shape.
- 7. The next step is adding designs to the glass. You can use various powders and metal bars to add color, design, and patterns to your glasswork. If you wish to add color, roll the heated glass your preferred color powder and reheat it in the glory hole furnace.
- 8. You can now start the actual glass blowing. It would be best to continuously blow into the blowpipe to develop a bubble and then take the glassware back to the glory hole furnace. Afterward, you need to return to the marver for more shaping and repeat these steps until you attain the desired size and shape.
- 9. Carefully transfer the glassware to a punty steel pipe by attaching it to the other end of the heated glass. The punty must be preheated first in a furnace so that it can adhere easily. The subsequent process involves breaking off the blowpipe and leaving the glassware attached to the punty. It can be a painstaking process as the product can fall off and shatter.
- 10. Take the glass back to the Gloryhole furnace and let it heat at 2250 F (1232 C). Afterward, return to the molding bench and use steel tweezers and other tools to make the mouth of the glass piece. You may need to redo this step severally until the mouth of the glass piece is symmetrical.
- 11. Once you create the glass’s mouth, you can now separate it from the punty. Hold the glassware over a box containing fire blankets and hit the steel pipe firmly so that the glass piece falls securely into the box.
- 12. The final procedure is placing your glassware in an annealing oven or kiln set at 950oF (510oC). Once you put the hot glass piece in the oven, slowly cool it down to room temperature for 15 hours. This lengthy cooling prevents the formation of cracks and breakages.
Three Top Tips For Glassblowing
Glassblowing is a delicate procedure that needs skill and attention to detail. If you wish to become an expert glassblower, kindly consider the following tips.
1. Invest in a high-temperature furnace thermometer. The furnace’s temperature plays a critical during glassblowing. Hence, it is always best to have a high-temperature furnace thermometer to ensure you are lowing glass with the right amount of heat.
2. Always use high-quality equipment. Your glassblowing equipment can significantly affect the final product. Quality equipment also helps to safeguard you from glassblowing accidents caused by faulty tools.
3. Remember that glassblowing requires patience. Expert glassblowers know the importance of patience. Blowing glass requires you to patiently combine raw materials, prepare a molten mixture, shape your glassware and allow it to cool.
If you are a novice glassblower, kindly understand you cans master this ancient craft overnight. Take time to learn this technique, and you will be a master artisan.
Glassblowing is an ancient technique that combines different physical and chemical properties to create beautifully crafted glass products. In closing, kindly remember that maintaining an optimal temperature of 1000 F (537 C)-2250 F (1232 C) is critical when blowing glass.
