But how did the balloon come to be? As simple as its construction may appear, the manufacture of the latex balloon actually requires a high degree of precision. After all, the walls of a balloon, when fully inflated, is extremely thin. Let’s take a look at just how a balloon comes to be.
Obtaining the latex
Balloons, for the most part, come in one of two forms: latex and foil. Of these, the former is by far the more widespread. Though it can also be synthesised, latex is mostly harvested from beneath the barks of certain sorts of flowing plants. In its natural state, it is a sort of milky gloop, whose purpose is to protect the plant from small insects which might like to eat it. Latex actually consists of a variety of different substances – sugar and protein being among them – and possesses unique properties which make it suited to the manufacture of balloons. It requires the addition of only a modest number of additives have been applied before it can achieve the shape and consistency required to form a balloon.
Did you know: When a balloon bursts the hole in the balloon actually breaks the sound barrier, creating a sonic boom!
Making the balloon
The process through which balloons are manufactured is almost entirely automated. It is this automation that allows such an enormous volume of balloons to be produced and the cost per unit to be kept relatively trivial. It is difficult, however, to estimate precisely how much that costs – different shapes and sizes of balloons will demand different quantities of latex and differently complex methods of automated assembly.
Did you know: Balloons were invented in 1824, the same year as the electromagnet.
The first stage is that the balloon form, which is a mould in the shape of an uninflated balloon, is cleaned. This is done using an acid bath, followed by a bath of clean water leading to a brushing finally. This process ensures that no particles are present underneath the skin of the latex, which would severely weaken the balloon when it is formed.
Next, the form is coated in a coagulant which is designed to attract particles of latex. This coagulant is heated to around seventy degrees and the balloon form is typically dipped into two separate baths before passing through an oven so that the coat can dry.
Once this coagulant has dried, the form is dipped into a vat of latex. The forms usually enter and exit the vat at a shallow angle; this is to prevent the formation of a bead at the bottom. The balloon then passes into a set of revolving brushes which roll the neck of the balloon into a bead, which is the end you blow into. This stage is vital, as without the beaded edge of the end of a balloon, it would prove impossible to inflate and tie up.
The form, covered in latex, is then dipped in hot water. This process, called leeching, will ensure that any excess nitrate is removed – though the latex will still stick to the form, coated as it is in coagulant.
After this, the balloon passes through an oven, where it cures for around twenty minutes. The temperature of this oven is usually around 90°C, though it can be higher or lower depending on the manufacturer’s preference. The balloon will then cool, with the assistance of fans.
At this point, the balloon can be removed from the form, as it will have solidified. This is typically done using a combination of air and rollers – though it can also be done by hand, if necessary.
It is essential that the latex dries as quickly as possible in order to prevent damage to the balloon. Have you ever noticed that the top of a balloon seems slightly darker than the sides? This, generally speaking, is because the wall of the balloon is thicker. When the balloon is being hung to dry, the still-liquid latex may flow downward, resulting in walls of uneven thickness. The bottom of a balloon, for example, may be thicker than its sides. Combatting this effect requires technology – sometimes a balloon may be spun as it is drying, thereby preventing gravity from pulling the latex in a given direction. This adds to the cost of the balloon, but it ensures that the balloon is more consistent and therefore reduces the chance of the balloon bursting before it has even been blown up and hence improves the overall quality of the balloon.