The complete guide
How to Choose a King Size Silk Pillowcase
The small annoyance that silk actually fixes
Most people do not go looking for a silk pillowcase because of some big problem. They go looking because of a small, repeated one. Hair that looks slept-on no matter what you did to it the night before. A cheek that wakes up with a crease pressed into it. A pillowcase that feels warm and a bit grabby when you roll over at two in the morning.
Cotton is a good fabric. It is also a fairly grippy one. Woven cotton fibres have texture, and texture creates friction. Hair catches on it, skin drags against it, and over a seven or eight hour night that adds up to a lot of small tugs.
Silk has a much smoother surface. Hair and skin slide across it instead of catching. That is the whole mechanism, and it is a fabric property rather than a treatment, so it does not wash out or wear off.
What momme means and why 22 is the common choice
Cotton bedding gets described by thread count. Silk does not, because thread count tells you almost nothing useful about silk. Silk uses momme, which measures the weight of the fabric.
Think of it as fabric density. A 16 momme silk is light. It feels slippery and a bit insubstantial, and it tends to wear faster at the seams and at the point where your head sits every night. A 25 momme silk is noticeably heavy and holds more warmth.
Twenty-two momme is where most bedding silk lands, and for good reason. It has enough weight to drape properly over a pillow and feel like real fabric under your hand, without crossing into the warmth of the heaviest grades. If you are comparing the best 22 momme silk pillowcase options against cheaper lightweight ones, that weight difference is the main thing you are paying for.
Grade 6A, explained without the mystique
You will see grade 6A on a lot of silk listings, and it does mean something specific. Silk is graded on the quality of the raw filament before it is woven, looking at length, evenness and cleanliness of the fibre. Grade 6A sits at the top of that scale.
Longer, more even filaments weave into a smoother face with fewer slubs and bumps. On a pale pillowcase you might not notice. On black, you notice immediately, because dark dyes show every irregularity in a weave. A black case made from poor silk looks uneven under lamplight. A black case made from 6A looks deep and consistent.
This pillowcase is listed by the maker as 100% mulberry silk at grade 6A, 22 momme.
Getting the size right
King size here means 20 x 36 inches (51 x 91 cm). That is the standard king pillow measurement, so it should slip over a king pillow without the seams straining or the fabric gaping.
The sizes worth knowing are these. Standard pillows are 20 x 26 inches. Queen pillows are 20 x 30 inches. King pillows are 20 x 36 inches. The width stays the same across all three, so the length is the only number you really need to check.
Before ordering, lay your pillow flat and measure it end to end. Pillows plump up differently depending on fill, and a very firm or deeply stuffed king pillow can feel tighter in a case than a soft one. If your pillow measures shorter than 36 inches, a king case will have slack at one end. That is not harmful, but a close fit looks and feels better.
For anyone hunting the best king size silk pillowcase, fit is more important than most people expect. A loose case creases under your head, and creases defeat the point of a smooth surface.
Why the zipper matters more than it sounds
This case closes with a hidden zipper along the open end. It is a small detail that changes how the case behaves night to night.
Envelope closures, where a flap of fabric folds back inside, are cheaper to make. They also work loose. Silk is slippery, so an envelope flap on a silk case tends to creep open and let the pillow edge out. Then you wake up with bunched fabric under your ear.
A zipper holds the pillow in fully. It also keeps the case contained in the wash, which matters because loose silk in a machine can snag. Keep the zipper closed every time it goes in the water.
Black, and who it suits
Black bedding divides people. It suits a dark or neutral bedroom, it photographs well, and it hides water marks and the faint traces that night creams and hair products leave behind. White silk shows all of that within a week.
The trade-off is lint and pale hair, which show against black the way they show against a dark jumper. A shake out before bed handles it. If you have pets that sleep on the bed, be aware of this going in.
Silk has natural lustre, so a black silk case is not flat. It catches the light with a quiet sheen rather than looking like a block of dark cotton.
Looking after it
Silk has a reputation for being delicate that it only half deserves. It does not like heat, bleach or harsh detergent. Keep it away from those and it holds up well.
Hand washing is the gentlest route. Cool water, a small amount of detergent formulated for delicates, a gentle swish for a few minutes, then rinse until the water runs clear. The maker also lists a gentle machine wash, which works if you zip the case closed, put it inside a mesh laundry bag and use a cool delicate cycle.
Do not wring it out. Press the water out between your hands or roll the case briefly in a towel. Then hang or lay it flat to dry, out of direct sun. Sunlight fades dark dye and weakens silk fibre over time.
Skip the fabric softener. Silk does not need it, and softener leaves a film that dulls the sheen. If you want to iron, use the lowest setting with the case turned inside out, though most creases drop out on their own once the case is on a pillow.
Washing every one to two weeks is normal. If you use leave-in hair products or heavy night creams, wash more often. Owning two cases makes the rotation painless, and it is why a lot of people who start with one end up buying the second.
Working out whether it is for you
A silk pillowcase is worth it if you turn over a lot, have long or textured hair, or simply want your bed to feel better than it does. It is not a cure for anything. It is a smoother surface, and that smoother surface changes how the night feels.
If you have never tried silk, start with one case rather than a full set. Sleep on it for a couple of weeks against your usual cotton case on the other pillow. The comparison is immediate and you will know quickly whether to buy the second.
If you are buying as a gift, black is one of the safest choices you can make. It works with almost any bedding and it does not look fussy.
The short version
This is a king size pillowcase, 20 x 36 inches (51 x 91 cm), made from 100% mulberry silk at grade 6A and 22 momme, in solid black, closing with a hidden zipper. One case per pack.
Check your pillow measures close to 36 inches long. Wash cool, dry in the shade, skip the bleach and the softener. Buy two if you want a matching pair on a king bed. Delivery runs 3 to 7 working days, and returns are open for 14 days from delivery as long as the case is unused and unwashed.