Sei Pillowcase Single

The Sei Pillowcase is 100% cotton, sateen weave, 600 thread count, garment-washed. Sei is MATTEO's highest thread count fabric, and it uses the same 120/2 Ne yarn in both warp and weft, which produces a balanced weave with a notably soft, silky face. Thread count measures weave density, not yarn quality or softness; Sei reaches 600 TC because going higher typically yields a stiff, dense fabric that does not breathe. The result is one of the purest, softest cotton sateen pillowcases in luxury bedding.

The Sei Pillowcase is available in Queen (20 x 33 inches / 51 x 84 cm) and King (20 x 39 inches / 51 x 99 cm). MATTEO does not offer a Standard size; for a Standard pillow insert, the Queen pillowcase works well and will hang slightly longer over the edge of the insert. It can be tucked in to create an envelope closure, or taken to a seamstress for a simple alteration.

Pillowcases loosely encase the pillow insert and are open on one side, making them easy to slip on and off. Shams are more fitted and use some method of closure, such as an envelope back or zipper, to keep the pillow in place. Pillowcases are typically used on sleeping pillows; shams are more common as decorative covers. The Sei Pillowcase is an open-sided pillowcase, finished with a half-inch hem and a double stitch detail.

The Sei Pillowcase is made from 100% long-staple cotton, garment-washed and dyed using non-toxic reactive dyes, with no synthetic fibers or harsh finishing chemicals. The garment-washing process relaxes the cotton fibers before the pillowcase ever reaches your bed, so the surface is soft against skin from the first night. For anyone with skin sensitivities, the non-toxic dyeing process and absence of synthetic blends make the Sei a considered choice in luxury cotton bedding.

Wash in lukewarm water with a gentle detergent and a cool rinse, separating light and dark colors. Do not overload the machine, as excess friction damages long cotton fibers. Tumble dry on low heat and remove promptly to reduce wrinkling; line drying gives the best results. If you prefer a crisp look, press while slightly damp on the Lightweight Cotton or Medium iron setting. Avoid chlorine bleach, alpha hydroxy acids, and benzoyl peroxide on garment-dyed colors, as reactive dyes are not resistant to whitening agents.

Garment-washing means the finished pillowcase, not the raw fabric, goes through a controlled washing process before it ships. On a 600 TC sateen like Sei, this pre-washing relaxes the weave and softens the cotton fibers so the pillowcase arrives with a lived-in hand feel rather than the stiffness common in high thread count fabrics that ship unwashed. Because garment-dyeing is an art rather than a precise science, MATTEO allows for a shade variation of +/- 10% from dye lot to dye lot. Learn more about MATTEO's garment-dyeing process.

The Sei Pillowcase is 100% cotton sateen, 600 thread count, garment-washed, designed and manufactured by MATTEO in Los Angeles. Most luxury hotel pillowcases use cotton sateen or percale in the 300 to 600 TC range, prioritizing a smooth, durable surface that holds up to repeated commercial laundering. Sei exceeds that standard in yarn quality, using the same 120/2 Ne yarn in both warp and weft for a balanced, silky weave that stays soft wash after wash. The half-inch hem and double stitch detail reflect the same construction rigor you would expect from hotel-grade linens.

The Sei Pillowcase is sold individually, so you can buy exactly the quantity you need. This makes it straightforward to replace a single pillowcase, mix colors across your bedding, or build out a set over time. Queen pillowcases are priced at $52.50 and King at $62.50 per pillowcase. Available colors include White, Off White, Oat, Greige, Salt, Smoke, Iris, Night, and others across both sizes.