Exothermic reaction

In chemistry, an exothermic reaction is one that releases heat. It is the opposite of an endothermic reaction. Expressed in a chemical equation:

Reactants → Product + Energy

In an exothermic reaction the total energy absorbed in bond breaking is less than the total energy released in bond making.

Endothermic reaction

An endothermic reaction is one in which the products have more energy than the reactants, and thus a net input of energy, usually in the form of heat, is required. Endothermic reactions are often described as reactions that "feel cold", and contrast with exothermic reactions, in which heat is released.

Electrical Firing Box

An e-match or electrical igniter is an electrical device used to trigger pyro compounds, and is widely used in professional pyrotechnical displays.

They must be hooked up to an Electrical Firing Box (EFB).

Simple, an EFB is a type of remote switch that cause the flow of current trough the e-match resistor end the consequently heating up of the pyro compound.

Electrical Ignitor

An e-match or electrical igniter is an electrical device used to trigger pyro compounds, and is widely used in professional pyrotechnical displays. It is a much safer alternative to visco fuse, black match, and other types of fuse.

Dud shell

Dud shell - shell rises but fails to burst at the proper height and falls to the ground as burning or live pieces. Dud shells have been responsible for many accidents involving children finding them after a fireworks show, thus it is important at first daylight to carefully check the whole area where shells are likely to have fallen the night before.


Dry-rolled is an attribute used to describe the way in which paste or glue has been applied on a sheet of paper before rolling a tube from it. A tube is dry-rolled if the major part of the sheet is rolled onto the former as is, unpasted, and paste or glue is applied at the final turn (at the edge) only.


Dross is a solid by-product of a combustion reaction. For example the residue left behind after a composition has burnt. Dross can be a useful by-product in relation to prime as the red hot dross particles have better ignition properties than hot gases.

Driven in

When the outer layer of a star, comet or any other mass of dampened composition dries in a way which traps moisture within the still wet core, the star, comet or other mass is said to be 'driven in'. While the mass will eventually dry, it is likely to take several months.


A die is a tool, not unlike a comet pump, used to mould compositions. It consists of a sleeve in which a cylinder slides, under which the composition is pressed. 

An example is to make Corned black powder.

Diaper method

Diaper method - is a method of mixing chemicals that are friction sensitive. Compositions that are friction or shock sensitive should never be rammed nor be passed through a screen.  Mixing via diaper method is usually done by laying a piece of newspaper on the ground and pouring all the chemicals into the centre of the sheet. Taking one corner at a time you lift the paper and roll the composition into itself.


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