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Protocol
Method steps
- Check the garment against the label limits The Super Washing Soda label says it is not for use on leather, silk, wool, or garments labeled dry clean only, and to check colour-fastness first.
- Put on rubber gloves for solutions and pastes Arm & Hammer highly recommends rubber gloves when using washing soda in solution or paste; its safety data sheet classes the product as causing serious eye irritation.
- 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 that matches your pack and task, since Arm & Hammer says to check the product packaging for specific uses and recommendations.
- Add it where the maker says Arm & Hammer: at the beginning of the wash cycle, or in the HE dispenser of an HE washer. Dri-Pak: crystals in the drawer if liquid detergent goes in the drum, and vice versa.
- Wash at the heat the garment allows The Super Washing Soda label says to use the hottest water the garment will allow.
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 (external link), a K-State Research and Extension laundering guide (external link) from 1991, Woolmark (external link) and an RSC Education feature (external link) 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.
| Task | Arm & Hammer Super Washing Soda | Dri-Pak Soda Crystals |
|---|---|---|
| Regular load | ½ cup with the usual liquid or powder detergent; HE washers: ½ cup | Dosed by water hardness (next row) |
| Hard water | 1 cup with the usual amount of detergent | 25 g medium, 50 g hard, 75 g very hard, with the soft-water dose of your usual detergent |
| Large, heavily soiled load | 1 full cup with the usual detergent | No separate dose in the pages we read |
| Organic stains, in the wash | No separate dose in the pages we read | 1 tablespoon added to your normal detergent |
| Stain paste | 4 tablespoons with ¼ cup warm water, rubbed gently into the dampened stain with rubber gloves, then washed as usual | No paste in the pages we read |
| Pre-soak | 2 tablespoons per gallon of warm water in a small tub, or ½ cup in a filled washing machine, for at least 30 minutes; then wash with ½ cup plus the usual detergent | A strong solution in warm water, one hour, then wash normally |
| Greasy clothes | A pre-treatment or pre-soak is often very helpful for greasy stains and embedded dirt on synthetics and cottons | Soak overnight in a strong solution, then wash as normal |
| Empty machine maintenance run | No dose in the pages we read | 300 to 500 g in an empty machine on the hottest setting |
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, and the empty-machine clean-out in how to clean a smelly washing machine.
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:
| Fabric or item | What the sources say | Verdict |
|---|---|---|
| Cotton and synthetics | Arm & Hammer: a pre-treatment or pre-soak is often very helpful for greasy stains and embedded dirt on synthetics and cottons | Covered by the maker's directions |
| Linen | Dri-Pak: heavy stains on cottons or linens go in a strong soda-crystal soak | Covered by the maker's directions |
| Wool | Arm & Hammer label: not for use on wool; Dri-Pak differs (see where the sources disagree) | Avoid, by the label |
| Silk | Arm & Hammer label: not for use on silk. Dri-Pak's own pick for hand-washing silks: a warm, mild solution of pure liquid soap | Avoid |
| Leather | Arm & Hammer label: not for use on leather | Avoid |
| Garments labeled dry clean only | Arm & Hammer label: not for use on them | Avoid |
| Items that may not be colourfast | Arm & Hammer: test a small, hidden area first; cool water for the pre-soak | Test first |
| Specially treated microfibres, such as waterproof sports and outdoor clothing | Dri-Pak: best cleaned with its pure liquid soap | Not the maker's pick |
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 and how to wash silk; for garments that may bleed dye, see how to stop colour bleeding.
Is it dry clean only?Read the garment’s care symbols in the decoder before a washing-soda wash or soak.
Decode the labelWhere the sources disagree
Two questions get opposite answers from our sources:
| Question | One source | The other source | What we take from it |
|---|---|---|---|
| Washing soda in hard water | Arm & Hammer: 1 cup with the usual amount of detergent | K-State (1991): precipitating softeners such as washing soda should not be used in an automatic washer; in hard water they form insoluble particles that can cling to fabrics and washer parts and leave a residue that is hard to remove | K-State's alternative: with very hard water, or clothes looking gray, a non-precipitating water conditioner in the wash and rinse water |
| Washing soda on wool | Arm & Hammer label: not for use on wool | Dri-Pak: a cold, mild soak for new woollens and blankets before washing in its liquid soap | The only package label we found rules wool out, so we list wool as avoid |
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.
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). 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.
- 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, 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.
Related reading
- How much laundry detergent to use — the detergent dose that washing soda goes in with.
- How to clean a smelly washing machine — the full machine clean-out.
- How to wash a wool sweater — wool washing methods.
- How to wash silk — silk methods and detergents.