How Condoms Work

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The Anatomy of a Latex Condom

The latex condom is a pretty basic invention. It's a baglike tube that's closed on one end -- typically with a small reservoir to hold semen -- and open on the other. The open end has a thin rim that helps hold the condom in place and makes it easier to roll the condom during manufacturing. Some condoms are flared, gradually widening from the closed end to the open one. Others are contoured to fit the shape of the glans and shaft of the penis.

The condom's primary purpose is to keep bodily fluids from different people separate. This helps prevent pregnancy by keeping sperm away from eggs, and it helps prevent diseases that are transmitted mainly through contact with sexual fluids, like semen and vaginal lubricant. To do this, the condom must cover the penis from the tip to the base. It has to be tight enough to stay in place and prevent leakage, but it can't be so tight that it inhibits function. The latex must be thin enough to allow sensation but not thin enough to risk breakage. For this reason, many nations set standards that govern condoms' exact dimensions and materials. The dimensions of today's typical latex condom are:

  • Length: at least 160 millimeters
  • Width: 52 millimeters (when laid flat)
  • Thickness: 0.07 millimeters

[source: Gerofi]

Powders like cornstarch, silica or magnesium carbonate typically coat the final product to help keep the latex from sticking to itself and make it easier to unroll. Lubricated condoms have a slippery fluid, typically made from silicone, applied at the factory. Spermicidally lubricated condoms have an ingredient that kills sperm, like nonoxynol-9 (N9), in the lubricant. However, medical research suggests that the amount of N9 used in condoms has little effect during sexual activity [source: Jeffries and Aitken]. Since it can cause vagi­nal irritation, which can make disease transfer more likely, it can do more harm than good.

Next, we'll look at the latex condom's journey from tree sap to foil-wrapped package.