Making glass is a very ancient process, the archaeological evidence of which dates back to before 2500 BC. Once considered a rare and prized art, glassmaking has become a common industry. Products made of glass are used in shops and homes in the form of containers, insulation, reinforcing fibers, lenses, and decorative art. While the materials used may vary, the general process for making glass is the same and is described below.
Steps
Method 1 of 2: Use an oven
Step 1. Get silica sand
Also known as quartz sand, silica sand is the main ingredient in glass making. Glass that does not contain iron impurities is necessary for the manufacture of transparent glass pieces. This is because the iron present makes the glass turn green.
- If you're handling extremely fine-grained silica sand, it's best to wear a mask, as inhaling it can irritate your throat and lungs.
- You can find silica sand in online stores. It is not very expensive and in small quantities it should not cost more than $ 20. If you want to operate on an industrial scale, specialty stores can offer competitive rates on large orders, sometimes under $ 100 per ton.
- If you cannot find sand sufficiently free of iron impurities, it is possible to counteract its tinting effect by adding small amounts of manganese dioxide. On the other hand, if you prefer greenish glass, leave the iron!
Step 2. Add soda ash and calcium oxide to the sand
Sodium carbonate (commonly known as soda) lowers the temperature required to make glass commercially. However, it allows water to pass through the glass, so it is necessary to add calcium oxide (or lime) to cancel this property. Magnesium and / or aluminum oxides can be added to make the glass more durable. These additives generally make up as much as 26-30% of the glass mix.
Step 3. Add other chemicals, depending on how you want to use the glass
The most common additive for a decorative glass is lead oxide, which provides the shine to the glassware, as well as the smoothness to facilitate its cut and to lower its melting point. Glasses can contain lanthanum oxide due to its refractory properties, while iron helps glass absorb heat.
Lead crystal can contain up to 33% lead oxide. However, the more lead oxide there is, the more skill it will take to shape the molten glass, so many lead crystal manufacturers opt for a lower lead content
Step 4. Add chemicals to produce the desired color on the glass
As stated above, iron impurities in quartz sand give glass a greenish hue, so iron oxide is added to obtain this hue, as well as copper oxide. Sulfur compounds produce a yellowish, amber, brownish, or even blackish hue, depending on the amount of carbon or iron added to the mixture.
Step 5. Place the mixture in a crucible or in a container that is resistant to heat
The container must be able to withstand the extremely high temperatures of the oven. Depending on your additives, your glass mixture can melt in a temperature range from 1500 to 2500 ° C. Also, your container should be easy to attach with metal hooks or hangers.
Step 6. Melt the mixture into a liquid
For commercial silica glass, you can make it in a gas oven, while specialized glass can be created using an electric melter or in a furnace.
Quartz sand without additives turns into glass at a temperature of 2300 ° C (4200 ° F). Adding sodium carbonate (soda) lowers the temperature needed to make the glass to 1500 ° C (2700 ° F)
Step 7. Homogenize and remove bubbles from the molten glass
This means stirring the mixture to a consistent viscosity and adding chemicals such as sodium sulfate, sodium chloride, or antimony oxide.
Step 8. Shape the molten glass
It is possible to do it in different ways:
- Molten glass can be poured into a mold and allowed to cool. It was the Egyptians who used this method and this is how many lenses are made today.
- A large amount of molten glass can collect at the end of a hollow tube, which is blown while turning. The glass gets its shape thanks to the air that enters through the tube, the gravity that pulls it and the tools that the glassblower uses to work the molten glass.
- Molten glass can be poured into a molten tin bath for support and then pressurized nitrogen sprayed to shape and polish. Glass made by this method is called float glass and this is how glass panels have been made since the 1950s.
Step 9. Slowly cool the glass in an oven
This process is called annealing and it removes any stress points that may have formed in the glass during the cooling process. Glass that has not undergone this annealing process is considerably weaker. Once this process is complete, the glass can be coated, laminated or treated to improve its strength and durability.
- The exact temperature to anneal glass can vary depending on its composition from as low as 400 ° C (750 ° F) to as high as around 550 ° C (1000 ° F). The rate at which the glass needs to cool can also change (generally larger pieces of glass should cool more slowly than smaller ones). It is advisable to research the proper annealing methods before beginning.
- A related process is tempering, in which formed and polished glass is placed in a furnace heated to at least 600 ° C (1,100 ° F) and then rapidly cooled ("tempered") with high-pressure air jets. Pressure. Annealed glass breaks into pieces when a pressure of 6000 psi (pound per square inch) is applied, while tempered glass breaks into small pieces at no less than 10,000 psi and usually around 24,000 psi.
Method 2 of 2: Using a Charcoal Grill
Step 1. Prepare a makeshift oven from a charcoal grill
This method uses the heat generated by a large coal fire to melt the silica sand into glass. The materials used are relatively cheap and easy to find; In theory, all you need is a quick trip to the hardware store and you are ready to make your own glass. Use a large charcoal grill; the standard size "dome" type works well too. Use the thickest and strongest grill you can. Most charcoal grills will have a vent at the bottom, open it.
- Even at extremely high temperatures in this method, it can be difficult to melt silica sand on a grill. Add a small amount (about 1/3 to 1/4 the volume of the sand) of soda, lime, or borax to your sand before you begin. These additives reduce the melting temperature of the sand.
- If you are blowing on the glass, have a long, hollow metal tube handy. If you're pouring it into a mold, make it ahead of time. If you want a mold that won't burn or melt in the heat of molten glass, one made of graphite is ideal.
Step 2. Consider the dangers of this method
This method will cause a conventional grill to exceed its normal temperature limits, so it may end up melting. This method can cause serious injury or death if it is carried out carelessly. Proceed with caution. Have at your disposal a large amount of earth or sand, or even an appropriate high-temperature extinguisher in order to smother the fire if necessary.
Step 3. Take all possible precautions to protect yourself and your property against high temperatures
Perform this method on a dirt or sandy surface outdoors with plenty of space available. Performing it on a smooth concrete surface that is not covered with sand or dirt could cause the concrete to explode if the molten glass falls. Do not use any equipment that is irreplaceable. stay away grill while heating the glass. You should also wear as much protective clothing as possible, including:
- oven mitts or potholders made of sturdy material
- a welder's mask
- a sturdy apron
- heat resistant clothing
Step 4. Get a shop vacuum with a long hose
Using duct tape or some other method, bend the hose so that it blows directly into the bottom vent without touching the main grill frame. You may want to attach the hose to one of the grill's legs or wheels. Keep the main part of the vacuum as far away as possible.
- Make sure the hose is secure and secure. If it becomes loose during the glass making process, no You should get closer to the grill as it will be extremely hot.
- Turn on the vacuum to check the position of the hose. If it is positioned properly, it will blow directly into the ventilation duct.
Step 5. Place charcoal inside your grill
Use more charcoal than you would need to grill meat. For a good result, it is necessary to fill the grill almost to the brim. Place the sand in a cast iron pot and, in turn, place it in the center of the grill, surrounded by the charcoal.
Hardwood charcoal burns more intensely and faster than briquettes, making it a better option if available
Step 6. Light the charcoal
Check the charcoal packaging to see if it is possible to light it directly or requires a lighter fluid. Let the flames spread evenly.
Step 7. Wait for the charcoal to heat up
If the charcoal turns grayish and gives off an orange glow, it's done.
Step 8. Turn on the vacuum to draw air into the charcoal
If air is fed from the base of the grill, the charcoal can burn at an extremely high temperature (up to 1000 ° C or 2000 ° F). Be careful, as large flames can develop.
If you still can't get hot enough temperatures, replace the cap while blowing air through the vent
Step 9. Once the glass has melted, very carefully use metal tools to remove and shape it
Due to the low temperatures of the grill method, molten glass can be stiffer and more difficult to work with than molten glass in a furnace. Use a tube, mold, or other tools to shape it as you normally would.
Advice
- If the sand or additives you use are coarse grains, pulverize them with a mortar or a mechanical grinder. Finer grain particles melt faster.
- You can use some types of beach sand instead of pure silica sand, although the resulting glass may be opaque, discolored, or of lower quality. Use the whitest, finest, and most uniform sand you can find.
- You can add pieces of powdered old glass to the sand before melting it for recycling into new glass. Old glass or “calcine” should be checked for impurities that can weaken new glass, such as bubbles.
When grinding the glass, wear a mask to avoid accidental inhalation
- Use a high-heat torch to join or cut small pieces, rods, or strips.
Warnings
- Always be careful around intense heat sources. Never try to make glass near children or pets.
- Extinguishing extremely hot fires with water can make the situation worse. For example, a fire burning at 2000 ° C is hot enough to split water (H2O) into its hydrogen and oxygen components, releasing a large amount of thermal energy. For very hot fires, it is best to have a large bucket filled with dirt or sand on hand.
Class D fire extinguishers contain sodium chloride (table salt) and are used to put out metal fires