# Washing Soda in Laundry: Doses, Uses and Fabrics to Avoid > Washing soda (soda crystals) in laundry: two makers' doses per task, the fabrics a package label rules out, safety data, and where sources disagree. **Published :** 2026-09-29 --- **Summary:** Add washing soda **with your usual detergent**. Arm & Hammer: **½ cup** for a regular load, **1 cup** for a large, heavily soiled load or hard water. Dri-Pak: **25 to 75 g** by water hardness. The Arm & Hammer label rules out **leather, silk, wool and dry-clean-only** garments. It causes serious eye irritation: wear **rubber gloves** for solutions and pastes. Arm & Hammer says its Super Washing Soda is 100% sodium carbonate; Dri-Pak says its Soda Crystals, also known as Washing Soda, have been used for over 100 years as a water softener, stain remover and in-wash additive. This page compiles both makers' directions with the [Super Washing Soda safety data sheet](https://www.oldtowncoleman.com/safety/sds-washing-soda.pdf), a [K-State Research and Extension laundering guide](https://www.pratt.k-state.edu/docs/facs/laundering-guide.pdf) from 1991, [Woolmark](https://www.woolmark.com/care/which-laundry-detergent-should-i-use-when-washing-wool/) and an [RSC Education feature](https://edu.rsc.org/feature/textile-conservation/2020240.article) on textile conservation. Each dose below is the maker's own, for its own product, and is not converted between cups and grams: Arm & Hammer says to check the product packaging for specific uses and recommendations. ## Doses by task: two makers side by side Each row gives the maker's own dose; the Arm & Hammer column is written for Arm & Hammer Super Washing Soda, the Dri-Pak column for Dri-Pak Soda Crystals. Arm & Hammer adds that the pre-soak should use cool water for non-colorfast items and for blood and egg stains. Dri-Pak's reason for pairing its hardness dose with the soft-water dose of detergent is cost: it says Soda Crystals can save you money by allowing you to follow the soft-water dosage for your usual detergent. The detergent dose itself is covered in [how much laundry detergent to use](/blog/how-much-laundry-detergent-to-use/index.md), and the empty-machine clean-out in [how to clean a smelly washing machine](/blog/clean-smelly-washing-machine/index.md). ## Fabrics: what the sources allow and rule out Each row sets what the washing-soda sources say about one fabric or item against the verdict we take from it: For wool and silk, two more sources add context. Woolmark says mild or neutral detergents have a relatively neutral pH, and advises avoiding heavy-duty detergents, bio detergents containing enzymes, and detergents containing bleaches. In museum textile conservation, RSC Education notes that anionic detergents, which work best in slightly alkaline conditions, around pH 7.5, suit cellulosic fibres but not silk and wool, which are susceptible to degradation; for wool and silk, conservators choose detergents that work best around pH 5. The Super Washing Soda safety data sheet lists a pH of 11.4. Washing methods for these fibres are in [how to wash a wool sweater](/blog/wash-wool-sweater-without-shrinking/index.md) and [how to wash silk](/blog/wash-silk-without-ruining-it/index.md); for garments that may bleed dye, see [how to stop colour bleeding](/blog/stop-color-bleeding-in-laundry/index.md). Read the garment's care symbols in the decoder before a washing-soda wash or soak. ## Where the sources disagree Two questions get opposite answers from our sources: The K-State guide dates from September 1991, and the Arm & Hammer directions are current. We found no newer university guidance on washing soda in automatic washers, so both are shown. ## Step by step: a washing-soda load These five steps follow the order the label and the makers set. ### 1. Check the garment against the label limits The Super Washing Soda package label says it is not for use on leather, silk, wool, or garments labeled dry clean only, and to check colour-fastness of garments first. ### 2. Put on rubber gloves for solutions and pastes Arm & Hammer highly recommends rubber gloves when using Super Washing Soda in solution or paste. The safety data sheet says repeated or prolonged skin exposure is likely to cause irritation. ### 3. Take the dose from the table row for your pack Arm & Hammer doses are in cups per load and task; Dri-Pak doses are in grams by water hardness. Use the row of the dose table that matches your pack and task, since Arm & Hammer says to check the product packaging for specific uses and recommendations. ### 4. Add it where the maker says Arm & Hammer says to add it at the beginning of the wash cycle, always following the machine instructions, or to the HE dispenser of an HE washer. Dri-Pak says that if the liquid detergent goes straight into the drum, the crystals go in the drawer and vice versa, so the liquid does not make them clump. ### 5. Wash at the heat the garment allows The same label says to use the hottest water the garment will allow. ## Other laundry uses the makers give Dri-Pak lists three more laundry uses for its Soda Crystals, each with its own method: - **Reusable nappies.** Dri-Pak says to soak the nappies in a hot solution of Soda Crystals before washing to remove stains, and to add Soda Crystals to the wash to soften the water and aid cleaning. - **Clothes carrying emollient creams.** Dri-Pak says Soda Crystals, used with its liquid soap, are effective at removing the greasy residue that emollients leave on clothing. - **Stiff towels.** Dri-Pak's re-fluff method starts with a 10-minute soak in a warm, medium solution of Soda Crystals, then a thorough rinse, then a normal machine wash with the recommended amount of detergent. More towel care is in [how to keep towels soft and fluffy](/blog/keep-towels-soft-fluffy/index.md). ## Safety: eyes, skin and what washing soda is not The Super Washing Soda safety data sheet lists a pH of 11.4 and classes the product as causing serious eye irritation. It lists acids as incompatible materials and says the product reacts with acid to form carbon dioxide. Arm & Hammer says Super Washing Soda should never be ingested. Two products share part of the name. Arm & Hammer says its Baking Soda is 100% sodium bicarbonate and its Super Washing Soda 100% sodium carbonate: they sound similar, but they are not the same (see [baking soda in laundry](/blog/baking-soda-in-laundry/index.md)). Dri-Pak calls caustic soda a toxic product, not to be confused with Soda Crystals, and does not recommend it because of the health and safety implications. For oxygen-bleach powder, see [sodium percarbonate in laundry](/blog/sodium-percarbonate-laundry/index.md). > **Warning:** > - **In the eyes:** the safety data sheet says to rinse cautiously with water for at least 15 minutes, remove contact lenses if present and easy to do, and obtain medical attention. > - **On the pack:** the Super Washing Soda label reads: eye irritant, harmful if swallowed, avoid eye contact; if contact occurs, flush immediately with water for 15 minutes. > - **If swallowed:** the label says to rinse the mouth and drink a glass of water, then call a physician, and to keep the product out of reach of children. ## Storage and septic tanks The safety data sheet says to keep the container closed when not in use and store it in a dry, cool place. Dri-Pak says Soda Crystals start to melt above 32 °C and set solid again as they cool, and advises a cool, dry place, ideally below 25 °C. The Super Washing Soda label says the product is safe for septic tanks, and Dri-Pak says its traditional cleaning and laundry products are safe for use in a septic tank system when used in a domestic setting. ## Your next step Check the garment's care label in the [care-symbol decoder](/tools/care-symbol-decoder/index.md), then take the dose from the row of the dose table that matches your pack and task. More detergent and additive guides are in the [detergents hub](/detergents/index.md). ## Related reading - [How much laundry detergent to use](/blog/how-much-laundry-detergent-to-use/index.md) — the detergent dose that washing soda goes in with. - [How to clean a smelly washing machine](/blog/clean-smelly-washing-machine/index.md) — the full machine clean-out. - [How to wash a wool sweater](/blog/wash-wool-sweater-without-shrinking/index.md) — wool washing methods. - [How to wash silk](/blog/wash-silk-without-ruining-it/index.md) — silk methods and detergents.