Decorative glass elements, such as vases, trays, centerpieces and more, add an interesting touch to the home. You can make them yourself by melting the old bottles you have accumulated. This is a perfect way to recycle old, but very beautiful glass and turn it into a new and elegant object. It takes some time and effort to perfect the casting technique, but by the end you will have found a way to use glass bottles for ever new projects.
Steps
Part 1 of 3: Prepare the Furnace and Bottles to Melt Them Safely
Step 1. Gather and wash all old glass bottles
Any type is great for your art project. This means you can use bottles of sodas, wine, condiments, perfumes and more. Before your chosen container is ready to melt, you need to make sure it's clean and dry. Remove all labels and even fingerprints!
- Stubborn labels can be left to soak in very hot soapy water. After a few hours or even a night, you shouldn't have any problem pulling them off.
- You will also need to remove any glue residue left from the label. After soaking in warm, soapy water, you should be able to scrape off the adhesive without too much difficulty. You can use a tool such as a putty knife, wallpaper scraper, or an old credit card.
- If the writing is painted directly on the glass, as is the case with Corona beer, for example, you can melt the bottles without worrying about it. However, the paint will remain indelibly fused to the material.
Step 2. Clean the furnace
Over time it can become dirty, accumulating dust and charred residues from other projects. All this dirt has a negative impact on the furnace's heating elements, greatly reducing their life. To avoid unnecessary and expensive repairs, clean it thoroughly before using it, respecting the instructions in the manual.
The time of cleaning is an opportunity to quickly inspect the machinery in a safe manner. Tighten any screws that appear to be loose, remove any flammable material nearby, and check that all equipment is in perfect condition
Step 3. Test the furnace
To make sure it works the way you want it, you should perform a test power up. It is advisable to always use the materials and respect the test procedures described in the furnace manual; however, you can test it with a freestanding pyrometric cone. Place one on each tray about 5cm from the inside of the oven. Afterwards you should:
- Set the correct furnace program for the test. Wait for the cycle to finish according to the instructions in the manual.
- When the program has finished and the oven has cooled down sufficiently, look at the pyrometer cone or material you used for the test. If you have used cones, you should notice that they have bent at an angle of 20 ° or more, but none of them should dangle underneath the trays. If you used different material, check the manual to learn how to interpret the results.
- If at the end of the test no cone has deformed, it means that the heating element of the oven or the relay is not working properly. In this case, you need to call a professional technician to take care of the repairs.
Step 4. Prepare the mold and tray if needed
If you do not protect the surfaces with which the molten glass will come into contact, it will remain "stuck" there forever. You will need to sprinkle a special product or non-stick powder on the mold and tray.
Alternatively, you can use a special furnace paper, such as fire retardant. This way, you prevent the molten glass from sticking to the oven or molds
Part 2 of 3: Melting the Bottles
Step 1. Choose whether to use molds or heat glass
These are the two main techniques of artistic glass processing. With the molds the material is generally melted in the furnace and poured in the liquid state inside a mold, to give it a new shape. When hot modeling, on the other hand, we proceed in such a way as to make the glass "collapse" on itself to create a new, "freehand" shape, which can be transformed into a centerpiece, a paperweight and much more.
You can also opt for a hybrid technique that encompasses both procedures. Glass molds are available at fine art stores, pottery supplies, and online. Thanks to these tools, you can shape the glass to give it a shape similar to that of the mold itself. In this way, you can create shallow bowls, vases and spoon holders
Step 2. Determine the boiler's heating cycle
The heating and cooling process of the boiler can be divided into several segments. Each of these phases must reach certain temperatures at a certain speed, respecting an established standard. The heating cycle you use affects the finished product and varies based on the type of glass you have decided to melt.
- The various types of glass are obtained through different chemical processes. Some react to a certain heat cycle better than others, so you'll need to experiment before you find the best settings for the blend you want to perform.
- You can find several free tips online, although your furnace manual should list the settings needed for some heating cycles. In some cases, the oven manufacturer's recommended process does not lead to good results and you will need to make adjustments.
Step 3. Put the glass in the furnace
Now that the bottles and machinery are clean, you've run an inspection, a test, and all surfaces are protected to prevent molten glass from sticking to them, you're almost ready to go. However, first you need to place the bottle stably in the center of the oven.
If you have decided to use a mold, you should either surround the bottle or position it so that it fills the mold itself as it melts. The best position to use depends on the specific characteristics of the machine
Step 4. Heat the oven
The first part of the process is to heat the bottle to no more than 260 ° C. You can also decide to set a lower temperature if you prefer a slower procedure. You will need more time, but you will protect the mold (if you have decided to use it) from thermal shock breakage.
- As the oven reaches the various temperatures according to the heating cycle you have set, you should make sure that at each interval it keeps the heat constant for the time set by the program. This is a short time, typically 10-12 minutes.
- When performing these jobs, you should always wear appropriate protective equipment, as recommended by the furnace manual. This means using heat resistant gloves and safety glasses.
Step 5. Reduce the rate of temperature rise, but continue to heat the glass
When the furnace reaches 560 ° C, the glass should be soft. The thinnest portions of the bottle, such as the middle one, should begin to sag on themselves. To obtain good results, you must ensure that, in this phase, the temperature remains constant throughout the bottle. For this purpose, it is recommended to reduce the temperature to 120 ° C.
At this point, the time during which you have to keep the temperature constant is greater than in the previous phases. The longer you wait, the more time you allow the heat to distribute itself evenly
Step 6. Melt the bottle as you wish
At this stage of the process the furnace should reach a temperature that allows the bottle to sag. From 704 ° C you should increase the temperature by 166 ° C per hour until it reaches 776 ° C.
When the furnace is at its maximum in the peak phase of the heating cycle, you should wait 10 minutes. Slight variations in holding time and temperature affect the melting of the bottle
Step 7. Eliminate internal tensions in the glass
This process, called annealing, consists in bringing the glass below its solidification point (537 ° C for many types of glass) and maintaining the temperature for about an hour for every 65 mm of material thickness. In this way, the structural tensions of the glass are eliminated, making it less susceptible to breakage.
- When the inside of the furnace has reached room temperature, you can open the machine and remove the glass. Be careful at this stage, as the glass may be hot.
- By opening the oven before it has naturally reached room temperature, you could cause a thermal shock and break or shatter your creation.
Part 3 of 3: Improving the Blending Technique
Step 1. Balance unstable bottles with granules
Glass broken into small fragments is sometimes referred to as "granulate". If the furnace is not perfectly level and you are having trouble keeping the bottle in the position you want, you can put some granulate on its sides to prevent it from rolling.
When the bottle begins to sag, it loses its circular shape and should no longer roll. However, until then the granulate will hold it steady
Step 2. Avoid the formation of sharp and jagged edges
When the bottle gets too hot, it bends inward to the lowest points of the mold, creating dangerous sharp edges. Lower the maximum temperature by 5.5 ° C at a time until you get the desired result.
- You can also smooth out sharp edges by reducing exposure times. Decrease them by about 5 minutes (or less) at the next opportunity. If you keep getting sharp objects, keep reducing the time this way.
- In some cases, better results are obtained by lowering the temperature and reducing exposure times. You will need to experiment to find the most suitable technique for the type of glass and furnace you are using.
Step 3. Take notes as you work
Glass melting is a precise process. Even a slight variation in the temperature or time of exposure to heat can completely change the result of the art project. You should pay special attention to the temperature, timing and rate of heating, as well as the type of glass you are melting.
Step 4. Perfect your technique
There are many small factors that have a great influence on the casting process. The amount of time you keep the temperature constant, the speed at which you raise or lower it, the number of bottles you want to blend in a single session, all play an important role. However, with a little time and practice you will soon be able to create beautiful works of art from melted bottles.
