Raw Silk vs Degummed Silk: Texture, Durability, and Why Not All Silk Is Slippery

Raw silk still carries sericin, the gum coating wrapped around each silk fiber, whereas in aqueous degumming processes, silk yarn has most or all of that coating washed away. Removing sericin changes how silk looks and feels, so one silk garment can feel dry and textured while another feels smooth and slippery.

Texture alone can't tell you whether silk is real, and lab studies don't name a durability winner between the two finishes. If you want a slippery feel close to your skin, fiber friction research points toward degummed silk.

Raw Silk vs Degummed Silk: The Sericin Difference

Sericin is the whole difference. A raw silk thread has two parts: fibroin, the structural fiber, and sericin, a gum layer that binds two fibroin strands tightly together and dissolves in hot water.

Degumming is the step that takes that layer off. In textile processing, cocoons or yarn go through water-based solutions; degumming removes sericin while retaining fibroin. The soluble sericin is washed out, while the insoluble fibroin stays. Mills do this on purpose to change the silk's sheen, color, and texture.

How much sericin comes off depends on the degumming method and degree of processing. That is why "raw," "partially degummed," and "degummed" work best as finish descriptions, not quality grades. Treat "partially degummed" as a general description rather than a precise measurement. A finish label tells you about the surface of a silk garment, not whether the fiber is better or worse.

When finish words on a label start to blur with fiber and weave words, our guide to silk finish terms sorts them into separate categories.

What Silk Friction Tests Actually Show

At the fiber level, yes, sericin makes silk less smooth. In a study that tied single silk fibers into slip knots and pulled them, sericin-coated fibers showed higher friction than degummed fibers. That made them more prone to friction as they ran through the knot.

The extra friction didn't act the same way in every knot. According to fiber slip-knot research, in a knot where the fiber could keep unfastening, the added friction helped raise fiber toughness. In a knot that tended to tie tight, it hindered sliding and contributed to damage and early fiber failure.

The scope matters here. The test measured individual fibers sliding through their own knotted loops. As slip knot testing shows, it did not measure woven fabric, a finished blouse or pajama set, or fabric moving against skin. Read it as evidence that sericin gives the fiber surface more grip, which helps explain the feel difference. It is not a skin-friction score for any garment.

Does Textured Silk Mean It Is Fake?

No. Rough or textured silk isn't a sign of a fake, and smooth, slippery silk isn't proof of the real thing either. As noted in textile degumming research, degumming changes silk's sheen, color, and texture, so two genuine silks can feel very different depending on how much sericin was removed.

Texture or touch alone cannot prove silk authenticity because finishes alter surface feel. Treat fiber content and finish as two separate claims in a listing. Fiber content says what the silk garment is made of, and a finish or hand description tells you how it should feel. Learning to read silk listings line by line helps you notice when one of those claims is missing before you buy.

Does Degumming Make Silk More or Less Durable?

Neither finish has been shown to make a longer-lasting garment. The available lab results measure single fibers, and they point in different directions depending on how the silk was degummed.

In one laboratory study, degumming treatments reduced fiber strength. Specific breaking strength and breaking elongation (how far a fiber stretches before it snaps) both fell after degumming. The biggest drop came with sodium carbonate, an alkaline degumming chemical. In that study, sodium-carbonate degumming cut those two values by 26% and 38%.

The method itself also changes the outcome. A review of greener degumming processes describes a study that used papain, an enzyme, under nearly neutral conditions. There, tensile results varied by method: papain-degummed silk showed higher tensile strength than silk treated with the traditional sodium-carbonate process.

Put together, these results show that the degumming process can change fiber strength. They don't rank raw silk against degummed silk for real-world wear. Neither study tested a finished silk garment through wearing or washing. A raw-versus-degummed label alone won't tell you which piece will last longer.

Choosing a Silk Feel for Close-to-Skin Wear

For a smoother, slipperier surface against your skin, look for degummed silk. For a drier, more textured hand, a finish that keeps some sericin may suit you better.

That direction rests on the silk friction study showing sericin makes individual fibers less smooth. Since removing sericin is what shifts silk's texture, the finish is the detail to look for. Treat it as a feel preference, not a promise of low friction or extra comfort from any one garment.

Don't guess the finish from the garment type. A pajama top or a blouse could be fully degummed, partially degummed, or textured by design. When you compare silk sleepwear or silk blouses and tops, check the description for a finish or hand note such as "degummed," "raw," or "textured." If the listing doesn't say, ask the seller about the finish or request a fabric swatch so you can feel it before you commit.

For sleep in particular, surface feel is only one part of the decision. Our sleepwear feel guide covers how fabric hand, fit for movement, and construction work together.

FAQs

What part of the silk remains after degumming?

Fibroin remains. In textile degumming processes, the insoluble fibroin is retained while soluble sericin is washed out along with other soluble ingredients, which the silk industry generally discards as waste. The fibroin is the fiber that gets spun, woven, and finished into fabric.

Can sericin be removed with just hot water?

Sericin does dissolve in hot water, which is why degumming is a water-based process. Mills also use added agents to control how the sericin comes off. Two documented examples are sodium carbonate, the traditional alkaline method, and enzymes such as papain.

How is enzyme degumming different from traditional degumming?

Enzyme degumming uses a protein-breaking enzyme instead of an alkaline chemical. In one study described in a greener degumming review, papain under nearly neutral conditions removed sericin completely at a concentration of 3.0 g/L. The silk fibroin still had a high molecular weight afterward. The goal was to strip the sericin without obvious damage to the fibroin underneath.

What do silk slip-knot tests actually measure?

In fiber knot testing, researchers pulled individual silk filaments through knot loops to measure fiber sliding and friction under tension. They did not test fabric against human skin or evaluate garment friction.

Can laboratory fiber tensile results predict garment lifespan?

No. Studies evaluating degummed silk fiber strength test single filaments under specific chemical conditions. They do not test woven garments through real-world laundering or wear.