At present, matches are a very ordinary household item, which at first glance is not of particular interest. Nevertheless, these thin wooden sticks have a whole range of properties that ensure the effectiveness and safety of their use. The composition of matches is very complex and includes many components, each of which performs its function.
What matches are made of
Any match consists of two parts:
- wood sticks, otherwise called straws;
- incendiary head.
The latter functions only when in contact with a special layer called a spread or grater. It is applied to the side surfaces of the box and serves for the initial ignition of a match. The chemical composition of the grater mass is very complicated.
Straws are most often made from pine or aspen, but poplar, linden and other species suitable for their properties can also be used. In this case, a thin tape (veneer) removed from the tree bark is used as raw material.
The head is the most complex and multi-component part of a match. It is an incendiary mass, mounted on the end of the straw.
What properties a match should have
In addition to the well-known ability to ignite as a result of friction on the boxes, matches have the following properties:
- the corner of the burned part of the straw does not smolder, which is necessary for fire safety;
- the flame that arose on the head does not go out immediately, but passes to the straw;
- slag from a burnt head does not crumble;
- the spread is not completely ignited (only at the point of contact with the head).
All these conditions are met due to the special composition of matches. Moreover, even the simplest part - straws - is impregnated with special chemicals.
Match Head Composition
Currently, there are many recipes for incendiary masses. However, in any match, the composition of the head always includes the following groups of substances:
- oxidizing agents - give oxygen, fueling the combustion process (bichromite or potassium chlorate, berthole salt, pyrolusite, etc.);
- combustible components - a variety of substances (sulfur, organic adhesives of plant and animal origin, phosphorus compounds) can be used in their quality;
- dyes - give the head a certain color;
- fillers - prevent rapid burning (iron oxide, ground glass);
- acidity stabilizers - prevent the occurrence of adverse chemical reactions (calcium carbonate, zinc oxide, etc.);
- bonding agents - fasten all components and at the same time possess combustible properties.
Some components closely interact with each other, performing several functions at once. So, pyrolusite not only serves as a source of oxygen, but also catalyzes the decomposition of bertole salt, and iron oxide prevents explosive ignition and at the same time gives the head a characteristic color (rust).
Thus, to say that the key component of the composition of the match - sulfur or phosphorus is fundamentally wrong. The presence of a combustible substance that can ignite due to friction does not in itself provide the desired effect. Ignition of the head and the spread of fire to the base of the straw is a whole chain of physicochemical processes.
The composition of matches also depends on their variety. So, some are able to ignite on any surface that provides sufficient friction, while others only when interacting with the corresponding plaster applied to the boxes. In the latter case, we are talking about the so-called safe matches, the heads of which do not contain the primary flammable substance, which is phosphorus sulfide. This component is present only in the grater mass.
Straw
Straw wood must meet several requirements:
- high porosity - provides good ability to absorb chemicals;
- stiffness - prevents the matchstick from bending when it hits the surface for the purpose of ignition;
- ease of handling.
The latter property is necessary for ease of handling of raw materials in the manufacture of thin bars of the desired size.
Straws cut from wood veneer are impregnated with special antizing agents (phosphoric acid, diammonium phosphate), which, in the process of burning a match, form a film on its surface. The wood near the head contains paraffin, which contributes to the effective distribution of the flame. Without this component, the match would go out almost immediately after a fire.
Mass
The composition of the grater mass also depends on the type of matches and the recipe of a particular manufacturer. The most template variant corresponds to the following scheme:
- combustible substance - made of red phosphorus;
- pyrolusite - performs the same functions as in the head;
- calcium carbonate;
- poorly burning substances (iron minium, kaolin, calcium carbonate, gypsum) - prevent ignition of the entire spread;
- antimony chloride;
- fastening component (glue).
The main role in ignition is played by red phosphorus. And the necessary friction is created due to the glass powder, which is present in the plaster and the head, giving their surfaces a roughness. This component also limits the spread of the flash on the spread.
How does a fire occur?
Ignition of a match does not begin at all on the head, but on a special surface of the box. As noted above, red phosphorus is responsible for the occurrence of the spark. When the head is rubbed on the spread, it turns into white phosphorus - a substance that is easily ignited by contact with oxygen. The result is a spark that ignites the sulfur and bertole salt contained in the head. Then other combustible components ignite.
At the same time, the flame on the head of the match is supported by oxidizing agents, and on the putty it immediately goes out due to substances that block its distribution.