Key takeaways
- Spunlace nonwoven at 40–60 gsm is the industry default for sheet masks.
- Cupra, Tencel and cotton differ in softness, absorption and cost.
- A laminated film backing holds serum but blocks breathability.
A sheet mask substrate is a nonwoven fabric, usually 40 to 60 grams per square metre, cut to a face shape and soaked in essence. The fibre type, the web formation and the bonding method decide how much serum the sheet holds, how it feels on skin, and how it behaves when the wearer moves.
1. Spunlace
Spunlace is the dominant process: fibres are entangled with high-pressure water jets, giving a soft, absorbent, lint-free fabric with no chemical binder. It is the standard for sheet masks because it is cheap, soft and compatible with a wet essence.
2. Fibre types
Cotton is soft and absorbent and holds serum well, at a higher cost. Tencel and lyocell are regenerated cellulose with a smooth hand and good absorption. Cupra is the softest and the most expensive, and is used in premium masks. Synthetic fibres such as PET and PP are cheap and hold less.
3. Weight
Weight determines serum capacity. A 40 gsm sheet holds around 8 to 10 ml of essence; a 60 gsm sheet holds 12 to 15 ml. A sheet that is too light feels flimsy and dries fast; one that is too heavy slides down the face.
4. Lamination
Some masks laminate the nonwoven to a thin film, which improves serum retention and prevents the sheet from drying. The downside is breathability: a laminated sheet feels occlusive and warmer. It is a legitimate choice for a treatment mask and a poor one for a daily mask.
5. The carrier film
Most sheet masks ship with a PE carrier film on one side to help the user unfold and place the sheet. The film is removed after placement and thrown away. A mask without a carrier is harder to handle but produces less waste, and the choice is a genuine trade.
6. Cutting
The face shape is die-cut, and the eye, nose and mouth openings decide fit. A sheet with narrow eye openings sits too high on many faces; a sheet with a single mouth opening fits more people than a sheet with a separate chin seam. Fit is a data question answered by a panel of face shapes.
7. Absorption and release
A good substrate absorbs evenly and releases serum to skin rather than holding it. Release depends on the fibre surface chemistry and on the essence viscosity. A sheet that stays wet for 20 minutes but leaves skin dry has poor release, which is a substrate problem rather than a formula problem.
8. Bioburden
The substrate is a dry good but not a sterile one. A sheet carrying a high bioburden into a preserved essence can overwhelm the preservation system. Ask the converter for the bioburden result per lot and test the first shipments.
9. Sustainability
Cotton has a high water footprint; Tencel uses a closed-loop solvent process; synthetic fibres are fossil-based but recyclable in principle. The pouch, not the sheet, is usually the largest environmental cost of a sheet mask. Claims should address the whole unit.
10. Cost
A spunlace sheet costs cents apiece; a cupra sheet costs several times more. The spread between the cheapest and the best substrate is large enough to change a product’s price tier, which makes the substrate a commercial decision as much as a technical one.
11. Where it fits
Sheet formats run across the sheet mask range; the premium alternative continues in the bio-cellulose entry.
Reference: Substrate supplier data and mask converting records, 2025
