Origins of the momme
The momme entered European parlance in the nineteenth century among traders buying silk from Japan. Until the early twentieth century, when it officially adopted the metric system, Japan used its own shakkanho system of weights and measures (itself derived from an ancient Chinese system).
The basic unit for mass was the kan (貫), which was 3.75 kilograms (the official conversion rate set by the Meiji government in 1891). All other weight measures were derived from it, including the monme (匁), which was one thousandth of a kan, or 3.75 grams (roughly an eighth of an ounce). Though the correct transcription of the word is “monme” the unit was popularized in the West as “momme.” We’ll probably never know why; it may have been a simple mistake, or it may have had something to do with the word’s pronunciation in an earlier transcription system. It is still used today as the traditional unit of measurement for silk as well as for pearls.
Measuring fabric weight
source: https://www.dainippon-tosho.co.jp/unit/list/kan.html
The textile industry uses a number of different systems and units to describe various qualities of a fiber, yarn, or fabric. You have probably run into the denier (abbreviated as den) commonly used to label tights and pantyhose, which expresses the linear density of fiber or yarn – the lower the number, the finer the fiber and the thinner the hose. (Fun fact: A silk filament measures roughly 1 den. The finest hose on the market today are around 5 den.)
When purchasing fabric for a sewing project, it’s useful to know how much the fabric weighs, a value often expressed in grams per square meter (g/m2 or gsm). This is the unit you will always see our fabric descriptions. Its meaning is fairly clear; quite simply, it expresses how many grams a square meter of fabric weighs. Some shops in North America use imperial measurements and express the weight of the fabric in ounces per square yard (oz.). You can convert from metric by simply dividing the gsm weight by a factor of 33.906 to get the weight in ounces. Metric, however, is the industry standard. Read more about fabric weight in general and why it pays to understand it in another article.
Converting mommes to gsm
Today’s momme is actually based on the imperial system. It tells you how many pounds a length of fabric 45 inches by 100 yards weighs. For those using the metric system, that is roughly 90 meters of fabric 114 centimeters wide. The formula for converting a momme into grams per square meter looks like this:
1 mm = 4,340 g/m2
Is momme a sign of quality?
Silk traders used to judge the quality of silk by its weight. Silk yarn is very fine, so whether you are talking about a featherlight chiffon or a heavy duchesse satin, the weight of the fabric will be determined by the density of the weave. So in general, the more mommes, the tighter the weave. In the past, a heavy, tightly woven, and (therefore) very expensive silk fabric reflected the wealth of its owner; weight was considered a mark of quality. That doesn’t mean, of course, that a sheer silk fabric necessarily had to be of inferior quality.
Fine, sheer fabrics simply must be lightweight in order to float prettily. On the other hand, apparel fabrics like satin call for more heft, implying a denser weave and a sturdier, smoother, more durable fabric. To make a fine, but opaque, silk scarf, the kind that falls just right, you’ll need a silk of 12–14 mommes. But for a dress, that same fabric would be too thin. For apparel, fabrics from 16 mommes up are a better choice.
If you need to compare silk with other types of apparel fabrics, you can’t necessarily rely upon a simple unit conversion. Polyester or rayon fabrics are generally heavier and even a light dress fabric will come in at 80–120 g/m2, which converts to a silk weight of 19–28 mm. However, the same volume of silk weighs less than an equal volume of other fibers, so that fabric is, in reality, more comparable to a silk of 16–22 mm. A 28 mm silk would be a very heavy luxury satin or duchesse!
Silk fabrics made of spun yarn (noil, some wild silks, etc.) are the exception because spun yarn is thicker. These fabrics are less densely woven than classic filament silks of the same weight. This certainly does not mean that they are of poor quality – they have the same benefits as any other silk (softness, breathability, lightness), but they’re made differently and have a more matte finish. Spun silks are often sought out for their unique appearance, relative ease of care, and lower price, all of which explains their growing popularity.
Classification of silk fabrics by weight – lightweight, medium and heavy
In theory, a fabric designer could get creative and turn out something wildly improbable like a heavy, opaque organza or a cheesecloth brocade, but most silk fabrics on the market today fit a certain mold and have a weight that is representative of their type. Luxury silks are generally those with a higher weight. It goes without saying that this is also reflected in the price.
There is no official definition for what makes a light, medium, or heavyweight fabric. In fact, each material is different (a lightweight silk will always weigh less than a lightweight cotton or wool – see fabric weights explained). Nonetheless, here’s an overview of how we categorize silk fabrics in Sartor.
- Lightweight silk
Silk fabrics with a weight of 14 mm and less, these are further divided into the sheer fabrics that are nearly transparent (3–6 mm) and semi-sheer fabrics that show through only in pale colors. Semi-sheer fabrics generally weigh 8–12 mm and are commonly used in dressmaking (dresses, blouses, and other lightweight garments).
- Medium-weight silk
Classic medium-weight silks generally weigh 16–19 mm. These include crêpe de Chine, silk satin, some dupionis, and silk serge.
- Heavyweight silk
Silk fabrics over 19 mm. They may be supple or stiff – this category includes heavy satins, crêpe marocain, and duchesse satin.
- Ultra-heavy silk
This special category of fabrics weighs in at 35–40 mm and includes very densely woven, hefty versions of crêpe marocain or duchesse satin and some 100% silk brocades with multiple colors woven in.
Typical silk fabric weights
LIGHTWEIGHT SHEER SILK
ORGANZA
5,5 mm (24 gsm)
CHIFFON
6 mm (26 gsm)
GEORGETTE
8 mm (35 gsm)
LIGHTWEIGHT SEMI-SHEER SILK
HABOTAI
8-12 mm (35-52 gsm)
CHARMEUSE
12-14 mm (52-60 gsm)
SILK SERGE
10-14 mm (43-60 gsm)
CLASSIC, MEDIUM-WEIGHT SILK
CRÊPE GEORGETTE
16 mm (70 gsm)
CRÊPE DE CHINE
16-19 mm (70-82 gsm)
TAFFETA
16-19 mm (70-82 gsm)
SATIN
16 mm (70 gsm)
DUPIONI
16-22 mm (70-95 gsm)
HEAVYWEIGHT SILK
HEAVY SATIN
22-30 mm (95-130 gsm)
DUCHESSE
30-40 mm (130-174 gsm)
CRÊPE MAROCAIN
30-40 mm (130-174 gsm)
SILK BROCADE
30-40 mm (130-174 gsm)
SILK JERSEY
35 mm (150 gsm)
SILK VELVET
40 mm (174 gsm)
Have you ever sewn with a really lightweight silk? A super heavy one?
Have you run into an interesting fabric that defies categorization?
Share your insights in the comments!
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