Soap Flakes For Laundry: Doses, Fabrics, And The Machines That Hate Them

Using soap flakes for laundry is not complicated, but it is different, and almost everything that goes wrong goes wrong for one of four reasons: the dose, the water, the temperature, or the machine. In that order of likelihood.

What follows is what we actually do, in a house in Arcadia with hard water and a machine that is old enough to not have opinions. We make the flakes and we wash our own clothes in them, which is a lower bar than it sounds like but is more than most people selling them can say.

Can I use soap flakes in my washing machine?

Yes, in most machines, with two caveats that matter.

The first is that soap makes more suds than detergent and modern machines are built to detect suds and respond by adding rinse cycles. A machine doing that is not broken; it is doing its job with a product it was not designed for. If yours starts adding rinses, halve the dose. It is nearly always the dose.

The second is that some high-efficiency machines from roughly the last decade will actively refuse to complete a cycle if the suds sensor trips repeatedly. If yours is one of those, this is not a fight worth having. Use the flakes for hand-washing, where they are better than detergent anyway, and use something else in the drum. We would rather tell you that than sell you a sack you end up resenting.

How much soap flakes to use per load

Start at two tablespoons for a normal load and adjust from there. Everyone wants a number, so that is the number, but the honest answer is that the right dose depends entirely on your water.

• Soft water: one to two tablespoons. You will use less than you expect and the water will feel slippery for longer than you expect.
• Medium: two to three tablespoons.
• Hard water: three to four, plus a handful of washing soda, or accept that this will be a struggle. See below.

Dissolve them first. Always. A jug, water hot enough that you would not keep your hand in it, stir until nothing granular remains, then pour it into the drum directly rather than into the drawer. Flake drawers clog. Not dangerously, just annoyingly, and then someone in the house announces that soap flakes do not work.

Why hard water ruins soap and not detergent

This is the single most useful thing to understand, and almost nobody selling soap flakes will tell you, because it is not flattering.

Hard water contains dissolved calcium and magnesium. Soap reacts with them. The reaction produces an insoluble curd — the grey ring in an old bathtub is precisely this — and every bit of soap that goes into making curd is soap that is not washing your clothes. On genuinely hard water you can lose a meaningful fraction of the dose before any cleaning happens at all.

Detergent does not do this. Detergents were engineered, deliberately and successfully, to be indifferent to water hardness. That is not marketing; that is the actual reason they took over the twentieth century, and pretending otherwise would be dishonest.

The fix, if you want one, is washing soda — sodium carbonate, sold in every supermarket, cheap. A tablespoon in the drum binds the calcium before the soap meets it. It is not our product and we do not sell it and it will make your flakes work roughly twice as well.

Can you make your own soap flakes?

Yes. Take a bar of plain soap and a box grater, use the coarse side, and let the shavings dry for a day or two before you put them in a jar. Freshly grated soap still holds moisture and will clump into a single lump if you seal it straight away.

It works perfectly well and we are not going to pretend otherwise. The only reasons to buy flakes rather than grate them are that grating a kilo is tedious, and that a bar dense enough to be worth grating costs about what the flakes cost.

Do soap flakes work in cold water?

Less well. Soap needs to be in solution to do anything, and cold water dissolves it slowly and incompletely. If you wash cold, dissolving the flakes in hot water first is not optional — it is the difference between a wash and a rinse with specks in it.

Thirty to forty degrees is where flakes are happiest. That is also where most clothing is happiest, so this is less of a compromise than it sounds.

What fabrics are soap flakes actually better for?

• Wool, cashmere, silk. Protein fibres. Detergent enzymes are designed to break down protein stains and do not distinguish very carefully between the protein in a stain and the protein in a jumper. Soap contains no enzymes. This is the case where flakes are not a lifestyle choice but simply the better tool.
• Linen and cotton for people who dislike the coated feeling. No polymer, so nothing is deposited. Towels stay absorbent instead of gradually becoming water-repellent.
• Babies, and anyone reacting to their laundry. Fewer ingredients means fewer candidates. Not a medical claim — just arithmetic.

Where flakes are the wrong choice

Heavily oiled workwear. Kitchen cloths that have met a roasting tin. Anything where the problem is grease and volume. Olive oil soap is mediocre at cutting oil, and we have written the full comparison including the cases detergent wins. If most of your laundry is that kind of laundry, the flakes will disappoint you and we would rather you knew now.

If you want the background first — what they are, what else they are for, how to read a flake label — start with what soap flakes actually are. Everything else we make is listed on the range.