Safety matches must be rubbed on the matchbox to burn, even if the match head is hit with a hammer, it will not catch fire. The earliest matches were "burn when you rub". Friction with any rough surface can make a fire. Even if a mouse bites the head of the match, it will burn; if it is hit with a hammer, it may explode.
The ignition principle of safety matches is that a chemical substance on the match reacts with a chemical substance on the matchbox. The heat generated by rubbing matches triggers this chemical reaction. If the match head is not in contact with the friction surface, the match will not burn.
We all know that the working principle of matches is to create fire by friction, which may let us think of the past drilling wood to make fire. In fact, with the development of society, the current matches are basically safety matches, common gift matches or images matches are safety matches, and they will only catch fire when they are rubbed in a specific place.
Now, matches are made with automated machines. The production capacity reaches 2 million pieces per hour, and matches are packed into boxes for later use. The production of standard matches is to first cut the logs into small sticks, each about 2.5 mm thick, then cut the small sticks into match sticks, and soak them in ammonium carbonate, which is to ensure that the sticks do not smoulder.
The match stick is inserted by a machine into a long steel strip with holes that moves constantly, and the end is immersed in hot paraffin; then the paraffin penetrates into the fibers of the wood, which can help the flame to burn from the outer layer of the match head to the top of the match stick. Then, the match is immersed in the mixture for making the match head. The match head of a safety match contains sulfur and potassium chlorate. Sulfur is used to produce flames, and potassium chlorate is used to supply oxygen.