Read the label
This may seem obvious, but it bears saying: Don’t just look at the product name, written in big, bold letters at the top of the page… you’ve really got to read the small print, scroll down to the textile content, if it’s there at all. The “silk dress” you’re looking at may have just a tiny percentage of silk fiber (or may be entirely synthetic… and “silky” in appearance only). When shopping online, you’ve got to rely on the merchant to provide accurate content information. If it’s a shop you don’t know, or you have any doubts, read the description very carefully. Be aware that merchants can get creative with the product name just to get you to click through. There’s no law against naming a product “silk satin” when its textile content is actually 100% polyester. If you keep your eyes open, you’ll see that “silk” or “silky” is very often used in product names just to indicate a fine, supple fabric regardless of content. If the merchant doesn’t provide textile content information at all, be on your guard.
The look and feel of silk
Anyone who has been working with silk for a long time can recognize it pretty much at first glance. Silk has a distinctive, subtle sheen that is extremely difficult to mimic. It is true that production techniques are forever improving, and manufacturers can now make some really attractive silk look-alikes, but where your eyes fail you, a simple touch will usually do the trick. Silk is soft (even stiff fabrics like taffeta and dupioni are not “hard” to the touch), smooth, pleasant against the skin. The silk filament is lighter than that of polyester or rayon, so silk fabric always feels lighter that a fabric of the same thickness made of a synthetic material.
You get what you pay for
The price itself may give away a silk imposter. You’re not likely to find real silk for the cost of polyester (though it’s not impossible that an honest merchant may offer natural silk at a small margin for less than someone else who sells a high-priced synthetic under slick “expensive is exclusive” marketing logic.) Other factors may affect the price: Whether the fabric was bought on order or acquired as overstock from the factory (often with no difference in quality), whether it was purchased directly from the source or through a number of middlemen. If it’s a special collection with printed graphics created by a designer, their fee will also be reflected in the cost.
Silk burn test
If you have a fabric in hand, it’s pretty easy to test whether it’s genuine. You can use this trick for unlabeled garments too, like a hand-me-down dress or something from a thrift shop. Just take a small bit of fabric – a few threads are enough – and set it alight. Some fabrics have warp and weft yarns of different materials, or a single thread may combine more than one material. If you don’t get a clear result, try pulling the threads apart and testing them separately.
At Sartor we label all of our fabrics with their true textile content, so you can choose from our silk fabric selection without fear.
Natural silk will not flame up, and a burnt bit of fabric will have scorched black fibers that crumble between your fingers. Synthetic imitations (right) will burst into flame and leave behind a hardened black mass that cannot be crumbled between your fingers.
Natural silk may be sensitive to heat, but it doesn’t burn very well. If you expose it to an open flame, it will smolder reluctantly, but will extinguish almost the moment you pull it out. Scorched silk fiber is black and there will be a hard, black knot at the end of the thread that you can crumble between your fingers. Burnt silk smells like burnt hair. Wool behaves in the same way as silk when put to the fire test, but you aren’t likely to confuse wool and silk – wool is heavier, warmer, rougher, itchier, and just plain woolier than silk.
Synthetic silk imitations made of polyester or nylon will melt as soon as they near the flame. They burn much more readily than silk. As with silk, there will be a black nub at the end of the thread after burning, but this one is hard and you can’t crumble it between your fingers. The strong odor of burnt synthetic filament is not at all like that of burnt silk.
Cellulose-based imitation silk: Rayon, cupro, modal, and acetate are common materials for making silk-like fabrics. Betraying their woody origins, they behave like paper when burnt – they burst into flame, the smoke smells like wood smoke or paper smoke, and when extinguished, a fine gray ash remains. Acetate fabrics – pretty, but fragile, silk imitators – can be identified by exposing them to acetone or an acetone-based nail polish remover, which will cause acetate to dissolve.
If you want to learn more about what’s what in the world of silk, check out the other posts in our silk series: