How Dry Cleaning Works: It’s Not What You Think

How Dry Cleaning Works: It’s Not What You Think

For me, dry cleaning has always belonged in a category of miracles, along with colour-safe bleach, dry shampoo and acupuncture. They seem to work, but is it only because we’d like to believe they do? So we decided to take a look past the counter and 1980s-style decals to figure out, what is dry cleaning, anyway?

Spoiler alert! It’s not actually dry.

Let’s start from the beginning. In the 1800s, a French gentleman named Jolly Belin spilled some kerosene on either a gross tablecloth or some dirty laundry, depending on who you talk to. His clumsy mistake turned up an unexpected result: the oily mixture of hydrocarbons banished the stains already built up on the fabric. Thinking he might have landed upon a better cleaner than soap and water, he started testing kerosene’s dirt removal powers. Pleased with his results, he opened a kerosene-powered cleaning service in Paris-or what’s now known as the first ever dry-cleaning establishment.

Kerosene (believe it or not) lifted dirt without messing up the clothing’s fibres. “There are certain fabrics and dyes and garments constructed with adhesives that are water sensitive, and dry cleaning doesn’t permeate the fibres or make them wet with water,” explains Alan Spielvogel, the director of technical services at the National Cleaners Association. Because kerosene doesn’t contain water, it can negotiate sensitive fabrics like wool or silk.

The problem with kerosene, though, is that it is flammable — not quite as flammable as gasoline — but enough that soaking our clothes in it can be a problem. And because dry cleaners kept so much of it on the premises, they were routinely denied insurance.

So solvents less likely to burst into flames came into fashion, and in 1948, cleaners settled on a non-flammable organic halogen compound called perchloroethylene, nicknamed perc. The liquid chemical lifts dirt from most common fabrics, doesn’t cause clothing to shrink or most dyes to fade, and it can be reused, which keeps costs down.

It works like this: When you drop a collared shirt or Pendelton throw off at the dry cleaners, both are tossed in a machine that looks and acts kind of like an over-sized front-load washer. The machine fills with solvent, and the drum rotates, swishing your clothes around in the (not-water!) liquid that loosens the stain. (While perc is still predominant, hydrocarbons, silicone-based solvents, glycol ethers, and liquid carbon dioxides also do the trick.)

The dirt either ends up in a filter, or is separated from the solvent through a distilling process. The perc (or similar) is sealed up in the machine and reused with each wash, transforming from liquid to vapor and back again. When the cycle is finished, these beastly washers take care of the drying, too.

But this souped-up wash cycle doesn’t always eliminate 100 per cent of the grime. The water-rejecting properties that make the perc and perc-like solvents so good for certain fabrics and stains also allow water-soluble marks to remain. Different chemicals are applied to treat the stains that require water to lift, typically before the machine wash. “Wet” treatments can target water-soluble food and drink stains, starches, fats and oils and plant-based marks. “Dry” spotting agents for more thoroughly soiled fabrics take aim at oily spots made by fats, waxes, cosmetics, paint and plastics.

A fancy pressing machine removes all the wrinkles, and then, presto, a perfectly clean and pristine shirt. Sure, it’s a bit of a miracle that my always-wine-stained-dress-for-every-wedding has survived for this long, but I’m relieved to know there’s more than magic and hope behind the dry cleaning process-and that for everyday fabrics like cotton, the good ol’ washer does just fine.

Image: Flickr/Parker Michael Knight