Sei Sheet Set

The Sei Sheet Set is 100% cotton in a sateen weave at 600 thread count, which is the highest thread count MATTEO produces. We stop at 600 TC deliberately: going higher typically yields a stiff, dense fabric that does not move or breathe. Sateen construction gives Sei its characteristic silky face, with the softer side designed to rest against your skin. The set is garment-dyed in our Boyle Heights factory in Los Angeles.

Sei is a 100% cotton sateen, which allows more airflow than high-count synthetic blends or thread counts above 600 that compress the weave into a dense, non-breathing surface. We held the thread count at 600 specifically because higher counts tend to trap heat rather than release it. If you sleep warm and want a smooth, silky hand without sacrificing breathability, Sei is the sheet we reach for.

Yes. Sei is 100% cotton with no synthetic fiber blends, and the reactive dyes used in our garment-dyeing process are set into the fiber rather than sitting on the surface. There are no enzyme softeners or chemical finishing agents applied to achieve the softness; the smooth hand comes from the sateen weave structure itself. If you react to synthetic fibers or heavily processed fabrics, a natural-fiber sateen like Sei is generally a straightforward choice.

Garment-dyeing means the finished sheets, fitted sheet, flat sheet, and pillowcases are all dyed together as a completed set in our Boyle Heights dye house, rather than dyeing the raw fabric before sewing. This produces color with more depth and a subtly lived-in quality you do not get from piece-dyed fabric. Because dyeing is an art and not a science, we allow for a shade variation of +/- 10% from dye lot to dye lot, which is an honest part of the process. All pieces within a single set are dyed in the same batch, so they will always match each other. You can learn more about our garment-dyeing process here.

Wash Sei in a lukewarm cycle with a gentle detergent and a cool rinse, separating lights from darks. Do not use bleach or any products containing chlorine, alpha hydroxy acids, or benzoyl peroxide; the reactive dyes used in garment-dyeing are not resistant to whitening agents. Tumble dry on low heat and remove the sheets promptly to reduce wrinkling, or line dry for best results. If you prefer a crisp look, press while slightly damp on the linen or high iron setting.

Every Sei Sheet Set includes one fitted sheet and one flat sheet in your chosen bed size, plus one or two pillowcases depending on the size. King and Cal King sets include two King pillowcases; Queen sets include two Queen pillowcases; Full sets include two Queen pillowcases with a Full fitted sheet; Twin and Twin XL sets include one Queen pillowcase each. All items in your set are garment-dyed together in the same color, so they match. If you want to mix colors, order the fitted sheet, flat sheet, and pillowcases individually.

Yes. The Sei Sheet Set is designed and manufactured by MATTEO in Los Angeles, California. Garment-dyeing is done in our Boyle Heights factory, where we have been making bedding since 1996. The cotton itself is sourced from leading mills to meet the fiber quality the weave requires.

Sei is a strong registry choice for anyone who wants a high-quality 100% cotton sateen set they will use for years. The silky hand, generous sizing options from Twin through Cal King, and the 10% savings when buying as a set rather than individual pieces make it practical at the point of purchase. Because all items are dyed together, the set arrives as a complete, coordinated unit, which matters when you are giving it as a gift. Queen sets start at $695 and King sets at $795.