The complete guide
How to Choose a Silk Pillowcase, Momme, Size and Fit Explained
The problem with buying silk online
Silk pillowcases are one of those products where the listings all sound the same and the numbers do not mean much until someone explains them. You see momme figures, grade letters, size charts in two different unit systems, and no clear way to tell whether any of it matters for the pillow sitting on your bed right now.
So here is the plain version. There are really only four things to check before you buy a silk pillowcase: what the fabric actually is, how heavy that fabric is, whether the case fits your pillow, and how it closes. Everything else is decoration. This guide walks through each one using the details of this particular case, which is 100% pure mulberry silk, Grade 6A long fibre, 22 momme, 51 x 76 cm, with a hidden zip.
What "100% mulberry silk" is telling you
Mulberry silk comes from silkworms raised on mulberry leaves. The fibre they produce is long and even, which is why it can be woven into a smooth, continuous fabric. When a listing says 100% mulberry silk, it means the fabric is that fibre and nothing else, with no polyester blended in and no cotton panel on the reverse.
That last point is worth checking on any listing. Some cases are silk on one face and a cheaper fabric on the other, which brings the price down. This one is silk throughout, so it does not matter which way up it goes on the bed.
Grade 6A is a fibre grading term. It refers to long fibre silk, meaning the strands are longer and more uniform before they are spun. Different suppliers apply grading slightly differently, but 6A is the top of the common scale you will see quoted on consumer silk bedding.
Momme, and why there is no thread count
Cotton sheets are sold by thread count, the number of threads in a square inch. Silk is not, and the reason is simple. Silk thread is so fine that counting threads would give you a huge, meaningless number. So the industry weighs the fabric instead.
Momme (pronounced "mummy") is that weight measure. A higher momme number means more silk per unit of fabric, which means a denser, heavier piece of cloth. Pillowcases on the market generally run somewhere between the mid teens and the mid twenties. This one is 22 momme, which puts it in the heavier part of that range.
Does heavier automatically mean better? Not exactly. It means more material, and a fabric that feels more substantial when you pick it up. Some people prefer a lighter silk for the way it drapes. If you are comparing two cases and one lists a momme number while the other does not list anything at all, the one with the number is at least telling you what you are getting.
When people search for the best silk pillowcase, momme is usually the specification they end up comparing, because it is the one number that is directly comparable between brands.
Getting the size right
This is where most returns come from, and it is entirely avoidable. The case measures 51 x 76 cm. That is a standard pillow size.
Before you order anything, go and measure your pillow. Lay it flat and measure it end to end along the long side. If that number is 76 cm or a little under, a standard case will fit. If it is noticeably longer, you have a king pillow and this case will not work. There is no stretching a woven silk case over a pillow that is too big for it, and trying will put strain on the seams.
For anyone shopping for a silk pillowcase for a latex pillow, this one is cut to suit the 60 x 40 cm and 70 x 40 cm latex pillows in this catalogue. Those are both within standard dimensions. One thing to expect: a latex pillow is firmer and holds its shape more than a soft fibre pillow, so a contoured or shaped latex pillow will show its outline through the case. That is normal for any fitted pillowcase over a shaped pillow, and it is not a fault in the case.
If you have several pillows of different sizes in the house, measure each one rather than assuming they match. Pillow sizing varies between countries and between brands, and the standard size silk pillowcase that fits one may not fit another.
The zip, and why closures matter
This case closes with a hidden zip set into one edge. Hidden means the zip tape sits inside the seam rather than running visibly along the outside.
There are two common closures on pillowcases, the zip and the envelope flap. An envelope flap is a folded overlap of fabric with no hardware at all. It is simple and there is nothing to break, but a pillow can work its way part of the way out during the night, especially a firm one that does not compress much. A zip holds the pillow in place along the full length of the opening.
The trade off with a zip is that it is a mechanical part and it needs a little care. Close it before washing, and do not force it if the fabric catches. On a hidden zip pillowcase, closing the zip before it goes in the machine also stops the teeth from catching on the silk during the cycle.
Choosing a colour
Eleven colours are available: black, blue, brown, gold, lavender, light blue, mint green, pink, red, silver and white. Every one of them is the same silk at the same price, so there is no quality decision hidden in the colour choice.
A few practical notes. Pale colours like white, silver and light blue show marks sooner but look clean and neutral against most bedding. Darker colours like black and brown hide marks better. If you are buying two cases for a double bed and want them to match exactly, buy them in the same order, since dye lots on natural fibre can vary slightly between production runs.
If you are buying a silk pillowcase gift and you do not know the recipient's bedroom, white or silver are the safest bets.
Care, honestly
Silk is a natural protein fibre, so it wants gentler treatment than cotton. The routine is not complicated, but it is not optional either.
Wash cold, 30 degrees or below. You can hand wash in a basin, or use a gentle machine cycle with the case inside a mesh laundry bag so it does not get tangled with zips and buttons on other items. Use a plain detergent with no enzymes and no bleach, because both of those attack protein fibres.
Air dry it, out of direct sunlight. Strong sun fades dyed fabric over time. Do not tumble dry. If you want it smooth and it has dried a little creased, iron on the lowest setting only.
Because the case needs to air dry rather than go straight through a dryer, a lot of people buy a second one so there is always a clean case on the bed on wash day. That is the practical reason to own two, more so than having a matching pair.
Who this suits
It suits anyone with a standard size pillow who wants silk on the bed, which is the short answer. It is particularly straightforward if you already own one of the standard size latex pillows from this catalogue, since the fit is already worked out.
It does not suit king pillow owners, and it does not suit anyone who wants a wash-and-forget pillowcase they can throw in a hot cycle with the towels. Cotton is better for that. Silk asks for a cold wash and a line dry, and if that does not fit how you do laundry, it is worth knowing before you order rather than after.
The short version
One pillowcase, 100% pure mulberry silk, Grade 6A, 22 momme, 51 x 76 cm, hidden zip, eleven colours at one price. Measure your pillow along its long side first. If it comes in at 76 cm or under, you are fine. Wash it cold, skip the dryer, and keep it out of the sun to dry. That is the whole decision.