Mulberry silk is the finest and most widely used silk in the world, produced by the Bombyx mori silkworm, which feeds exclusively on the leaves of the mulberry tree. That single-source diet is what makes it special. It produces unusually long, smooth, uniform fibres, which is why mulberry silk is softer, stronger and more lustrous than any other silk. 

As silk specialists with over 20 years’ experience, we’re asked what is mulberry silk more often than almost any other question, and we work with 6A grade, long-strand mulberry silk every day. This guide explains what mulberry silk is, how it is graded, what momme means, and how to choose well. If you would like to feel the difference for yourself, explore our mulberry silk bedding.

Below we cover everything from how mulberry silk is made and why it costs what it does, to the grading and momme figures worth understanding before you buy.

Table of contents

1. What is mulberry silk?
2. How is mulberry silk made?
3. Can mulberry silk be harvested in any other way?
4. Mulberry silk grades explained: what does 6A mean?
5. What is momme, and what momme is best?
6. Mulberry silk vs other types of silk
7. Mulberry silk benefits
8. Why is mulberry silk so expensive?
9. How to choose mulberry silk: what to look for
10. Does mulberry silk require special care?
11. What products can be made with mulberry silk?

What is mulberry silk?

Mulberry silk is a natural protein fibre spun by the domesticated Bombyx mori silkworm. It takes its name from the mulberry tree, because this species is fed exclusively on mulberry leaves. Because of this controlled diet, it produces silk filaments that are longer, cleaner and far more consistent than those from silkworms with a varied diet. That’s why mulberry silk is regarded as the highest quality silk available and accounts for the vast majority of the world’s silk production.

In practice, this means an unmatched softness, a natural lustre rather than a synthetic shine, and strength despite how delicate the fabric feels. It’s why mulberry silk is the material of choice for luxury bedding, dressing gowns and high-fashion clothing. Browse our silk pillowcases to see what long-strand mulberry silk feels like.

What is mulberry silk made of?

Mulberry silk is made of two natural proteins. The first is fibroin, the structural filament that forms the thread itself and gives silk its strength and smoothness. The second is sericin, a natural gum that binds the filaments together in the cocoon and is largely washed away during processing. Because silk is protein-based, its structure is closer to human hair and skin than any plant or synthetic fibre, which is a large part of why it feels so comfortable against the body.

Origins of mulberry silk

The story of mulberry silk starts in China over 5,000 years ago. Legend states that the process was uncovered when a silkworm cocoon fell into the tea cup of empress Si Ling Chi as she was sitting under a mulberry tree. Instead of removing the cocoon from the cup, she watched as it dissolved and laced the tea with a remarkable shimmer.

Inspired by the shine, she went on to develop what is known as sericulture, the production of silk, and learned how to collect these filaments, test their strength, and weave them into garments. This process remained shrouded in mystery for thousands of years, closely guarded by China as a valuable commodity that enabled the ancient silk trade.

Over time, production became more widespread across East Asia, which ultimately led to a boom in popularity in the 13th century as Italian traders imported the material to Europe. Soon, silk production factories appeared on the continent, serving nobles and royals, and by the 15th century the traditional silk road started to decline. Today, many countries are able to craft mulberry silk, but the product remains a luxury material.

How is mulberry silk made?

Despite thousands of years passing since the first discovery of silk, the process of making silk remains largely the same. At around five to six weeks, the moth larvae start to build a cocoon from a single continuous strand of fibre. That one filament can run to roughly a kilometre in length, which is precisely why mulberry silk is so smooth. Fewer joins mean fewer weak points and a more even surface.

Once the cocoon is complete, the filaments are unravelled, or reeled, cleaned to remove the sericin gum, and carefully woven into the fabric we know as silk. Because the Bombyx mori is fed solely on mulberry leaves, this is an entirely natural process that generates second-to-none quality, though dyes may be used at a later stage to add colour.

The distinction that matters most here is between long-strand and short-strand silk. Long-strand silk uses the full, unbroken filament, which is what produces the smooth, durable fabric used in fine bedding. Short-strand silk uses broken or leftover fibres spun together, and it is noticeably less smooth and less hard-wearing. All Gingerlily silk is long-strand.

Can mulberry silk be harvested in any other way?

Yes. Traditionally, the mulberry silk production process requires that the silk cocoons be boiled whole in order for the strands to unravel. The moths sadly do not survive this process. Nothing goes to waste, however, as the boiled silkworms are then used as a local food source, prized as a delicacy and valued for their protein and vital vitamins. The alternative method, in which the moths leave the cocoon around ten days later than the silk would traditionally be harvested, is not widely practised. This is because it yields much less silk and is even more labour intensive, which means that peace silk, as it is known, is almost double the price of regular mulberry silk.

It should be noted though that both methods of crafting mulberry silk are classed as environmentally friendly, as the process does not use synthetic dyes, fabric blends, or harmful technology as other materials might. Where land is required, mulberry trees are planted, which can help to absorb excess CO2 and provide food and shelter for other wildlife. This is because these trees do not only produce leaves, but berries that are rich in vitamins and minerals.

Mulberry silk grades explained: what does 6A mean?

Raw silk is graded on a scale that runs from the lowest classifications up through C, B and A, and then through 2A, 3A, 4A, 5A and 6A at the top. 6A is the highest grade of mulberry silk available.

Grading assesses the raw silk before it is woven, and it is based on the qualities that determine how the finished fabric will look, feel and last:

• Filament length, with longer, unbroken fibres scoring highest.
• Uniformity and evenness of thickness along the thread.
• Cleanliness, meaning freedom from defects and impurities.
• Tensile strength, elasticity and cohesion.
• Colour consistency across the lot.

In practice, higher grade mulberry silk resists snagging and fraying, holds its lustre for longer and feels noticeably smoother against the skin. Lower grades use shorter or less uniform fibres, which is why cheaper silk can pill, dull or wear through more quickly.

All Gingerlily products are made from 6A grade mulberry silk, and our bedding also carries OEKO-TEX certification, confirming it has been tested for harmful substances.

What is momme, and what momme is best?

Momme, written as mm and pronounced mom-ee, is the measure of silk’s weight and density, in the same way that thread count is used for cotton. One momme equals roughly 3.75 grams per square metre, so a higher momme number means a heavier, denser fabric.

Grade and momme are often confused, but they measure different things. Grade describes the quality of the raw fibre. Momme describes the weight of the finished fabric. A silk can be high grade and lightweight, or heavier and lower grade, so it is worth checking both.

For silk bedding, momme generally runs from about 19 to 25. All of these are suitable, and the difference is one of weight and drape rather than quality:

• Around 19 momme is light, fluid and beautifully breathable, with an elegant drape. This is the weight we use for Gingerlily bed linen.
• Around 22 momme is a little heavier with a denser handle.
• Around 25 momme is the heaviest commonly used for bedding, with the most substantial feel.

Below roughly 16 momme, silk becomes too sheer for bedding and is better suited to scarves and lightweight garments. Above 25, the fabric starts to lose the fluidity that makes silk feel so distinctive. You can read more in our guide to momme silk.

Mulberry silk vs other types of silk

Mulberry silk is not the only silk available, but it is the finest. The main comparisons worth knowing:

• Tussah silk, sometimes called wild silk, comes from silkworms that feed on oak and other leaves in the wild. Their varied diet and the fact that emerging moths break the cocoon produce shorter, coarser, naturally golden-brown fibres. Tussah is more textured and less lustrous than mulberry silk.
• Eri and muga silks are other wild varieties, valued for their character but rougher and less uniform than mulberry.
• Charmeuse is not a type of silk at all, but a weave. Silk charmeuse is mulberry silk woven to give a glossy face and a matte reverse, which is a common source of confusion when shopping.
• Satin is also a weave rather than a fibre, and most satin sold today is synthetic polyester rather than silk.

So when you compare mulberry silk with the alternatives, the difference comes down to fibre length and consistency, and that is what produces the softness, sheen and durability mulberry silk is known for. Our guide to silk versus satin pillowcases explains the weave distinction in more detail.

Mulberry silk benefits

The benefits of mulberry silk go well beyond how it looks. Because it is a smooth, natural protein fibre, it behaves quite differently from cotton or synthetics.

• Gentle on skin - Silk’s smooth surface reduces the friction that causes overnight sleep creases, and it absorbs far less moisture than cotton, so skin retains its natural hydration.
• Kind to hair - Less friction means less breakage, frizz and tangling, which is why silk pillowcases are so widely recommended for curly and textured hair.
• Naturally hypoallergenic - Mulberry silk resists dust mites, mould and common household allergens, making it a sound choice for allergy-prone sleepers.
• Temperature regulating - Silk is breathable and adapts with your body, keeping you cool in summer and warm in winter.
• Durable - Long-strand mulberry silk is one of the strongest natural fibres, and cared for properly it lasts for years.

You can read more in our guide to how silk pillowcases benefit hair and skin.

Why is mulberry silk so expensive?

Mulberry silk fabric is an expensive buy, but for good reason. The process of crafting it is time consuming and labour intensive. To put this into perspective, it takes roughly 5,500 cocoons to produce a single kilogram of raw silk, and those silkworms must be fed a controlled diet of mulberry leaves throughout. The threads are then carefully reeled, cleaned and woven.

Additionally, this type of silk is one of the finest and strongest available, with an exquisite feel and a lustrous sheen that makes it highly sought after. Combine that with its natural benefits, and it is easy to see why mulberry silk commands a premium for high end bedding and clothing. You can read more about these benefits in our can silk make a difference to your sleep blog.

How to choose mulberry silk: what to look for

If you are buying mulberry silk, a few checks will tell you most of what you need to know.

1. Check it says 100% mulberry silk - Blends, silk-look fabrics and polyester satin are all sold in ways that can be mistaken for the real thing.
2. Check the grade - 6A is the highest, and a seller confident in their silk will state it.
3. Check the momme - For bedding, look for 19 to 25. If a seller does not publish a momme figure at all, treat that as a warning sign.
4. Look for long-strand silk - this is smoother and more durable than short-strand.
5. Look for certification - certification such as OEKO-TEX confirms the fabric has been tested for harmful substances.
6. Feel it if you can - Genuine mulberry silk has a soft, almost buttery smoothness and a gentle shimmer that looks similar on both sides, rather than the mirror-like gloss of synthetic satin.

Does mulberry silk require special care?

Yes, if you own mulberry silk products, there are a few extra steps to keep them looking their best. You should never hang silk in direct sunlight or place it in a tumble dryer. However, it is not necessary to take it to a specialist dry cleaner every time you want to wash it. You simply need to wash at low temperatures, no more than 30 degrees, and use a designated silk detergent.

You can read more detailed care instructions in our guide to caring for your silk.

What products can be made with mulberry silk?

Traditionally, mulberry silk was used to make religious and spiritual pieces alongside luxury clothing for nobility. Today, it is most commonly seen in bedding, nightwear and accessories.

For bedding, mulberry silk transforms how a bed feels and performs, keeping you comfortable and temperature-regulated through the night, while adding depth and texture to a room. Silk pillowcases, duvet covers, flat sheets and fitted sheets are the natural starting point, and silk filled duvets and pillows extend the same benefits to what goes inside the cover.

For nightwear and accessories, silk dressing gowns, eye masks and hair accessories bring the same softness to your routine, and a silk robe and eye mask together are an easy way to recreate a spa-like feeling at home. Silk travel accessories carry it with you.

All Gingerlily products are crafted from 6A grade, long-strand mulberry silk, whatever you choose.

Discover the magic of mulberry silk with Gingerlily

There is no wonder why, after thousands of years, mulberry silk continues to be one of the most revered fabrics in the world. No longer exclusive to royalty and nobility, it brings comfort, longevity and unparalleled style to any home.

Now you have the full answer to what is mulberry silk, how it is graded and what momme to look for, you can buy with confidence. Browse our mulberry silk pillowcases, bedding and accessories, and explore the benefits of mulberry silk at home.

Related reading

What is Momme Silk? Gingerlily’s Guide to Momme

Silk vs Satin Pillowcases: Which Is Better?

How Silk Pillowcases Benefit Hair and Skin

Silk Bedding for All Seasons: Your Year-Round Guide

How to Wash Silk Bedding: The Complete Silk Care Guide