Everyone knows St. Marc washing soda—especially from our grandmothers' cleaning routines. This powerhouse, made from soda crystals, is gentler than pure washing soda yet equally effective for stripping, deep cleaning, and scouring. Best of all? Its unbeatable price. My grandmother shared these tried-and-true tips, honed over decades of household expertise.
Discover 8 surprising ways to use St. Marc washing soda at home:
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It goes by three names: St. Marc detergent, washing soda, or caustic soda. As noted, St. Marc powder is less aggressive than traditional washing soda, with similar applications. Don't confuse it with baking soda. Washing soda is essentially the liquid form of caustic soda (sodium hydroxide), made by diluting flakes in water. It's perfect for cleaning, degreasing, and stripping—without harmful lung-irritating gases. Always wear gloves, as it can dry out and irritate skin.
For dull, lime-encrusted, or stained tiles, dilute St. Marc in lukewarm water, scrub the floor, and rinse thoroughly. Your tiles will gleam like new. Note: Test modern tiles with protective coatings in a discreet spot first to avoid damage.
To prep previously painted wood for repainting, apply St. Marc with a brush. Let it sit a few minutes, then scrape. The old paint lifts right off for better adhesion.
Revive lackluster paint on radiators, walls, or furniture: Wipe with a lightly damp sponge in diluted lukewarm St. Marc solution, rinse, and dry. Stains and dullness vanish, restoring shine.
Skip the steamer—St. Marc is simpler and cheaper. Saturate wallpaper with a sponge in diluted solution, wait minutes, and peel. It slides off effortlessly. This is one of its most famous uses.
For clogged sinks, mix St. Marc with water in the drain and let sit overnight. Rinse well. Pipes should flow freely. Repeat if needed, but close the door to limit vapors.
Sprinkle half a teaspoon of flakes into pipes, flush with hot water, and leave overnight before rinsing. Odors are eliminated for good.
Tackle greasy ovens, hoods, hobs, and backsplashes: Apply diluted solution, scrub, and rinse. Grease dissolves completely.
For limescale in coffee makers or kettles, run a St. Marc-water mix through, let sit hours, then rinse. It also descales washing machines: Add a glassful, run empty at 40-60°C.
Though effective, St. Marc is a strong chemical—use with care. Wear gloves (prevents 3rd-degree burns), goggles (against splashes), and a mask (especially for respiratory issues). Ventilate well. Mix only with water. Store away from kids and pets. For skin contact, rinse immediately (white vinegar neutralizes). If ingested, call poison control—do not induce vomiting.
