Polyester is oleophilic — it attracts oil at a molecular level — which is why cooking oil stains on polyester are notoriously stubborn [S1]. Blot immediately, cover with baking soda to absorb the oil, then work dish soap into the stain before soaking in Sil Fleckensalz (Grade 2.4). The critical detail: never dry polyester until the stain is completely gone. Heat fuses oil into polyester's plastic structure, making removal nearly impossible.
How to Remove Cooking Oil from Polyester
⏱️ Treat Before Washing — Oil Sets in Polyester
How to Remove Cooking Oil from Polyester — Step by Step
- Blot excess oil immediately. Use paper towels to press and absorb surface oil. Work from the outside of the stain inward to prevent spreading.
- Apply baking soda. Cover the stain generously with baking soda (or cornstarch). These powders absorb oil that has begun to penetrate the fiber. Wait 15–20 minutes, then brush off. If the powder looks oily, apply a fresh layer.
- Pre-treat with dish soap. Apply dish soap directly to the stain and work it in with an old toothbrush using gentle circular motions. Dish soap's surfactants are specifically designed to break oil-water surface tension [S1]. Let sit 15 minutes.
- Soak in oxygen bleach. Dissolve 1–2 tablespoons of Sil 1 für Alles Fleckensalz in warm water (40°C). Submerge the polyester garment for 30–60 minutes. Sil's lipase enzymes are especially effective on polyester because they break the triglycerides into fragments small enough to separate from the oleophilic fiber surface [S2].
- Machine wash warm. Wash at 40°C — the standard temperature for polyester. Don't exceed 60°C as polyester can deform at high heat.
- Inspect before drying. Check the stain area while wet. If any dark spot remains, repeat the dish soap treatment. Never tumble dry until the stain is completely gone — heat permanently bonds oil into polyester [S3].
What Not to Do
- Don't put it in the dryer while stained. This is the #1 mistake. Heat fuses oil into polyester's thermoplastic structure, making removal virtually impossible [S3].
- Don't use very hot water. Polyester softens at high temperatures. Warm (40°C) is ideal — hot enough to keep oil fluid, cool enough to protect the fiber.
- Don't ignore the stain. Oil spreads through polyester over time via capillary action. A small splatter can become a large stain if left untreated.
- Don't use bleach on colored polyester. Chlorine bleach can damage polyester dyes. Oxygen bleach (Sil) is color-safe.
Why Polyester and Oil Have a Special Problem
Polyester (polyethylene terephthalate) and cooking oil share something in common: both are derived from petrochemical building blocks. This molecular similarity makes polyester oleophilic — it has a natural affinity for oils and fats [S1]. Cotton absorbs oil through physical capillary action, but polyester actually bonds with oil through van der Waals forces between similar molecular structures. This is why the same cooking oil splatter that washes easily out of cotton clings stubbornly to a polyester shirt. You need surfactants powerful enough to break these molecular interactions.
Best for Oil on Synthetics
Sil 1 für Alles Fleckensalz
Grade 2.4Why Sil works for cooking oil on polyester: Sil's lipase enzymes cleave triglyceride molecules (the main component of cooking oil) into glycerol and free fatty acids — both water-soluble [S2]. On polyester specifically, the enzyme's ability to work at the fiber-oil interface is crucial because simple surfactants struggle to break the van der Waals attraction between polyester and oil. Sil's dual-action formula (enzymatic breakdown + surfactant emulsification) addresses both the chemical bond and the physical removal.
For cooking oil on polyester: Use warm water (40°C), soak 30–60 minutes. For set-in stains, extend soaking to 2–4 hours. Pre-treat with dish soap before soaking for best results.