A brief lesson on condom production
Condoms are mainly made from natural rubber, the sap of the rubber tree (latex milk). Originally, the rubber, which had coagulated and solidified in the air, was crushed and liquefied again in a petrol mixture. However, this process was labour-intensive and also highly flammable – explosions were not uncommon in the production facilities.
Consequently, a method was sought to concentrate the latex, i.e. to reduce its water content and thus make it lighter for transport, whilst still keeping it in a liquid state. The solution ultimately lay in thermal evaporation with the addition of ammonia, which prevents the latex from coagulating. If the natural latex concentrate is heated during further processing, the ammonia volatilises as a colourless gas with a pungent odour.
Today, around 700 condoms can be produced from one litre of latex. To do this, glass moulds are dipped directly into the liquid latex milk. This consists of 60 per cent rubber tree sap, 38.5 per cent water and 1.5 per cent sulphur and zinc oxide. After a brief dip in the latex milk, which is heated to between 20 and 30 degrees, the moulds are dried and are then coated with a thin film of rubber. Further dipping and drying stages follow until the condom, in its raw state, has reached a thickness of between 0.03 and 0.08 millimetres. The rim at the open end is formed by brushing. The condom is then vulcanised in hot-air chambers at 110 to 130 degrees and subsequently stripped from the glass mould. This is followed by a washing cycle. The water contains silicone and talcum powder, which are used to coat the condoms so that they no longer stick together. They are then dried at around 85 degrees.
To check whether they are leak-proof, they are immersed in an electrolyte solution. Any hole in the condom reduces the electrical resistance. If the light at the testing station comes on, electricity is flowing through the condom, meaning it is leaking and is discarded. Brand manufacturers carry out further random checks on the material (leak-tightness test, inflation test, elongation test, test for microbiological purity). In the tear resistance test, for example, a condom must withstand being stretched to seven times its normal size without sustaining any damage. GD