Why silk is so expensive: what you’re really paying for

In summary: the price of a mulberry silk piece is decided long before it's cut—at the cocoon. Reeling yield, degumming, yarn grade, momme, finishing: each step removes material or adds to it. Understanding these factors means knowing how to read a label and tell an honest discount from an empty promise.

I'm often asked the question as an affectionate reproach: why is it so expensive? The answer has less to do with the word “luxury” than with the arithmetic of the material. I learned this by handling skeins: silk is a fiber that loses a lot before it reaches a bed.

It all starts with the cocoon, and the cocoon gets smaller

Mulberry silk is the only common textile produced by an animal as a continuous filament. A cocoon is reeled—not spun—to obtain a single continuous thread. And at every stage, the scales tip the wrong way.

• Reeling yield. Generally, 30 to 40% of a cocoon's dry weight becomes usable raw silk. The rest is lost to waste, silk waste and irregular layers.
• Degumming. Raw silk thread is coated in sericin, a glue-like protein that is removed in a hot bath. This process causes the thread to lose another 20 to 25% of its weight. It gives silk its fluid feel and drape—but costs grams.
• Structural scarcity. Global production is around 150,000 tonnes a year, about 80% of it in China. On the scale of the global textile industry, that's a drop in the ocean: cotton production is measured in tens of millions of tonnes.

Result: depending on quality, origin and market conditions, raw silk sells for around $30 to $80 per kilo. Before weaving, dyeing or sewing. Keep that ballpark figure in mind when you see a full bedding set priced like synthetic bed linen: the raw material alone wouldn't fit into that price.

The five factors that really determine the price

Momme: the easiest factor to verify

Momme (abbreviated mm) measures fabric weight. It describes the amount of material—and that's why it explains most of the price difference between two otherwise identical pieces.

• 16.5 mm — a credible entry point. Fluid and lightweight, perfect for an accessory or summer garment.
• 19 mm — the most common weight for bedding and shirts. About 15% more material than 16.5.
• 22 mm — dense, comfortable silk for a pillowcase you want to last for years. Expect roughly a third more silk than with 16.5.
• 25 and 30 mm — the exception, for exceptional pieces. The price reflects the material, as you’d expect.

If a listing doesn’t specify the momme, it doesn’t tell you how much silk you’re buying. Of all the things left unsaid on a label, this is the most telling. I’ve explained how to read this measurement in detail in Momme: the measurement that makes all the difference when buying silk.

What the price doesn’t buy

Let’s be clear, because this claim keeps coming up: you’re not paying for skincare. You sometimes read that a silk pillowcase “nourishes the skin thanks to its proteins.” Research into silk proteins certainly exists—a 2025 review by Stradczuk-Mazurek et al. in Macromolecular Bioscience takes stock of sericin in dermatology (PubMed reference)—but its title already says it all: from preclinical studies to future clinical applications. The research focuses on extracted and formulated sericin, mostly at the preclinical stage.

In finished textiles, sericin is specifically removed during degumming. So what you’re buying is a smooth, lightweight, breathable surface, not a cosmetic treatment. At the same price, I’ll always prefer a brand that states the momme over one that touts a benefit.

How to read a price without getting ripped off

Discount season is approaching, and that’s precisely when price differences become hard to make sense of. Three simple checks are enough.

1. Compare the surface area. A 50 × 70 cm pillowcase has an area of 0.35 m² per side; a square 65 × 65 pillowcase has an area of 0.42 m². So two identical prices don’t necessarily mean two identical offers. The same goes for a bedding set: add up the items actually included.

2. Look out for meaningless words.

• “Satin” on its own describes a weave, not a fiber: satin can be made of polyester. “Silk satin”, on the other hand, specifies the material. I’ve explained the difference in silk or satin: what’s the difference?
• “Natural silk”, “silk touch”, “silk effect”: none of these terms guarantees mulberry silk.
• “100% silk” without a momme or grade: the fiber may be genuine, but the quantity remains unknown.
• A grade stated without any evidence: learn how to read the labels in Grade 6A and IFTH: decoding silk labels.

3. Be wary of markdowns with no explanation. A credible discount applies to a discontinued color, existing stock, or a season. A permanent 70% discount on an item that is always available mostly tells you about the listed reference price, not the value of the item.

The real calculation: cost per use

A properly washed silk pillowcase—cold water, delicate cycle, gentle detergent, no fabric softener—will last for years. Divide the price by the number of nights rather than the number of items, and the gap with a synthetic alternative replaced every eighteen months closes. Two honest caveats: silk doesn't like repeated rubbing against a zipper, tumble drying, or direct sunlight. So its cost per use depends as much on your habits as on its momme weight.

If budget is a constraint, start with the item that touches the most skin over the smallest area: a 19- or 22-momme silk pillowcase. It's the only one that gives you a verdict after one night.

Frequently asked questions

Why can two “100% silk” pillowcases cost twice as much?

Most often, it's due to three factors combined: a different momme weight (16.5 versus 22 means about a third more material), a different thread grade, and finer craftsmanship—an inner flap, hems, and an invisible closure.

Is momme an indicator of quality?

It's an indicator of the amount of material, not the quality of the thread. Both matter: a high momme weight with irregular thread won't produce a beautiful finish. Always consider both together.

Does a very low price necessarily mean it's not silk?

Not necessarily, but it almost always means a compromise somewhere: low momme weight, short fibers, less colorfast dye, or a smaller item than advertised. Ask for the momme weight and exact dimensions—two questions that settle the debate.

Should you wait for sales to buy silk?

Waiting for a sale on an item you'd already had your eye on is reasonable. Choosing an item because it's on sale is less so: you risk buying a momme weight that doesn't suit you. Decide on the momme first, then the timing.

Does silk cost more to care for?

No, if you wash it in cold water on a delicate cycle with a gentle detergent and let it dry flat, out of the sun. Dry cleaning isn't necessary for bed linen.

The bottom line

The price of silk tells a story of a supply chain: a cocoon that loses two-thirds of its weight, a thread that is reeled rather than spun, a protein removed to make the material soft. Nothing mysterious—just grams. And once you know how to count them, you can shop much more wisely. Browse our mulberry silk selection, or start with bedding if the bed is what you want to change first.

— Colette, for the StudioSoie Journal