Fireworks manufacturers in Bulacan.
Here they are making small triangulo or triangle firecrackers. Internationaly they are also known a Polumna firecrackers, Mexican style firecrakers of Black Bermudas. Many things can be used to create a triangulo's casing. From news paper to craft paper or many kinds of tape. Usually in a 1.5"x12" strip. They are filled with Black Powder . Black Powder is a chemical compound invented in the 9th century and was practically the only known propellant and explosive until the middle of the 19th century. As such it has been superseded by more efficient explosives such as smokeless powders and TNT.The current standard for black powder manufactured by pyrotechnicians today is 75% potassium nitrate, 15% charcoal and 10% sulfur. Triangulos are easy to make, inexpensive, and because they are made of paper materials, they pose minimal shrapnel danger.