How to make glass?9 steps to make glass by charcoal barbecue
Prepare a makeshift furnace from a charcoal barbecue grill. This method uses the heat generated by a large charcoal fire to melt silica sand into glass. The materials used are relatively cheap and common - theoretically, all you'll need is a short trip to the hardware store to be ready to make your own glass. Use a large charcoal barbecue grill - standard-size "dome" models work well. Use the thickest, sturdiest grill available. Most charcoal grills will have a vent on the bottom - open this vent.
Even at the extremely hot temperatures reached in this method, it can be difficult to melt silica sand in a grill. Add a small quantity (about 1/3 to 1/4 of your sand's volume) of laundry soda, lime, and/or borax to your sand before you begin. These additives lower the sand's melting temperature.
If you're going to blow your glass, have a long, hollow, metal tube handy. If you're going to pour it into a mold, prepare your mold beforehand. You want a mold that won't burn or melt from the heat of molten glass - graphite works well.
Know the dangers of this method. This method will push a conventional barbecue past its normal temperature limits - so hot that it's even possible to melt the grill itself. This method can cause severe injury or death if it's attempted recklessly. Proceed with caution. Have a large quantity of dirt or sand or a fire extinguisher rated for high temperatures on hand to smother the fire if needed.
Take every possible precaution to protect yourself and your property from the high heat. Attempt this method on a concrete surface outdoors with plenty of space. Don't use any irreplaceable equipment. Stand clear of the grill while you're heating the glass. You should also wear as much of protective clothing as possible, including:
Heavy duty oven gloves or mitts
A welder's mask
A heavy duty apron
Get a shop vacuum with a long hose attachment. Using duct tape or another method, angle its hose so that it is blowing directly into the bottom vent without touching the grill's main body. You may want to fasten the hose to one of the grill's legs or wheels. Keep the main vacuum unit as far away from the grill as possible.
Make sure the hose is secure and will not move - if it comes loose while you're making your glass, you should not approach the grill if it's extremely hot.
Turn the vacuum on to test your hose positioning. An accurate hose will blow directly into the vent.
Line the inside of your grill with charcoal. Use more charcoal than you would for grilling meat. Successful results have been achieved by filling the grill nearly to the brim. Place a cast-iron pot or crucible containing your sand in the center of the grill, surrounded by charcoal.
Hardwood (or "lump") charcoal burns hotter and quicker than briquette charcoal, making it a better choice if it's available.
Light the charcoal. Consult the charcoal's packaging to know whether your charcoal can be lit directly or whether it requires lighter fluid. Allow the flames to spread evenly.
Wait for the charcoal to get hot. When the charcoals are grayish and emanating an orange glow, they're ready. You should be able to feel the heat from simply standing near the grill.
Turn the shop vac on to introduce air to the charcoal. Charcoal fed with air from the bottom can burn extremely hot (up to 2,000 degrees Fahrenheit. Beware - large flame-ups may occur.
If you're still not able to reach high enough temperatures, experiment with replacing the lid while introducing air through the vent.
When your glass is molten, very carefully use metal implements to remove and shape it. Because of the low temperature of the grill method, the molten glass may be stiffer and harder to work than glass from a kiln. Shape it with a tube, mold, or other tools as you normally would.