Diatomaceous Earth: Nature's Versatile Secret for Health and Home
Natural Ingredients Series
Diatomaceous Earth: Nature's Versatile Secret for Health and Home
Formed over millions of years from the fossilised shells of microscopic algae — this ancient sedimentary powder has quietly become one of the most useful substances in the modern natural home.
Somewhere beneath ancient lake beds and ocean floors lies one of nature's most quietly remarkable substances — a soft, chalk-white powder made entirely of the skeletal remains of algae so small they are invisible to the naked eye. Diatomaceous earth has been used in agriculture, pest control, filtration, and health for decades. More recently it has found a growing place in natural cosmetics and handmade soap. This guide covers everything you need to know about it.
What Is Diatomaceous Earth?
Diatomaceous earth (DE) is a naturally occurring, sedimentary rock formed from the fossilised silica shells — called frustules — of diatoms. Diatoms are single-celled aquatic algae that have been present on Earth for at least 200 million years and are among the most diverse and ecologically important organisms in the world's oceans and freshwater systems.
When diatoms die, their silica shells sink to the bottom of lakes and oceans and accumulate over millions of years into thick sedimentary deposits. These deposits are mined, dried, and milled into the fine white-to-off-white powder we know as diatomaceous earth.
- Silicon dioxide (SiO₂): 80–90% — the primary structural component; amorphous (non-crystalline) in food-grade DE
- Aluminium oxide (Al₂O₃): 2–4%
- Iron oxide (Fe₂O₃): 0.5–2%
- Calcium, magnesium, sodium oxides: trace amounts
- Water: up to 8% in raw DE; reduced in processed grades
What makes DE remarkable is not its chemical composition — it's its physical structure. Under a microscope, each diatom frustule is a unique geometric masterpiece — intricate patterns of pores, ridges, and chambers that give DE an extraordinarily high surface area relative to its weight. One gram of diatomaceous earth can have a surface area of up to 200 square metres — giving it exceptional adsorption, filtration, and abrasive properties that no synthetic powder fully replicates.
"Diatomaceous earth is not a chemical invention. It is the compressed record of hundreds of millions of years of aquatic life — nature's most patient engineer."
Food Grade vs Pool Grade: The Critical Difference
Not all diatomaceous earth is the same, and using the wrong grade can be genuinely dangerous. Understanding the difference between the two main commercial grades is the single most important thing to know before purchasing or using DE.
| Property | Food Grade DE | Pool / Filter Grade DE |
|---|---|---|
| Processing | Milled and dried — no heat treatment | Heat-treated (calcined) at 1000°C+ |
| Silica type | Amorphous — less than 1% crystalline | Crystalline (cristobalite) — up to 60%+ |
| Inhalation risk | Low — irritant dust, wear mask | HIGH — causes silicosis. Never inhale. |
| Safe for consumption | Yes — food & human approved | No — never consume |
| Safe for pets | Yes — used in animal feed | No |
| Safe for garden | Yes | No |
| Safe for cosmetics | Yes — cosmetic/food grade | No |
| Use case | Health, home, garden, cosmetics, food preservation | Pool filtration systems only |
| Colour | Off-white to white | Bright white (from calcining) |
Never use pool-grade DE for any purpose other than pool filtration. The heat treatment converts amorphous silica to crystalline silica — a known carcinogen that causes irreversible lung damage (silicosis) upon inhalation. Pool-grade DE is dramatically more dangerous than food-grade and must never be used around people, pets, food, or gardens. Soapmaid's diatomaceous earth is food-grade and safe for all home, cosmetic, and garden applications.
How Diatomaceous Earth Works
DE's effectiveness across such a wide range of applications comes from two distinct properties — its physical structure and its chemical composition. Understanding which property is at work in each application helps you use it more effectively.
8 Versatile Uses for Diatomaceous Earth
Diatomaceous Earth in Cosmetics & Soap Making
The cosmetic use of diatomaceous earth is growing rapidly in Australia as more formulators look for natural, multifunctional additives that do more than one job. DE brings three distinct benefits to cosmetic formulations: gentle physical exfoliation, oil and sebum adsorption, and a naturally matte, silky skin feel.
In Cold Process Soap
At 1–2 teaspoons per 500g of oils, cosmetic-grade DE adds a subtle exfoliating texture to cold process soap. It is finer and less scratchy than poppy seeds, oats, or walnut shell — making it well-suited for facial bars and sensitive skin formulations. It also produces a slightly creamy lather quality and imparts a soft, slightly powdery after-feel to the skin.
DE Exfoliating Facial Soap
Cold Process · 500g- Olive oil 40% · 200g
- Coconut oil 25% · 125g
- Shea butter 25% · 125g
- Castor oil 10% · 50g
- NaOH (7% SF) ~63g
- Distilled water ~160g
- Diatomaceous earth (at trace) 1 tsp in 1 tbsp carrier oil
- Kaolin clay (at trace) 1 tsp in 1 tbsp carrier oil
- Lavender essential oil 2% · 10g
In Face Masks
DE can be used in powdered face mask formulations as a partial or full substitute for kaolin clay. It provides gentle exfoliation that kaolin alone doesn't deliver, while still adsorbing excess sebum and mattifying oily skin. A simple base mask: 2 parts kaolin, 1 part DE, pinch of activated charcoal — mix with water, rosewater, or raw honey to form a paste.
In Dry Shampoo
DE is an effective dry shampoo base at 30–50% of a dry shampoo formula, combined with arrowroot powder and kaolin clay. Its high surface area absorbs scalp oil efficiently and helps the formula blend invisibly into hair — especially on lighter hair tones. Add a small amount of mica for shimmer on darker hair to prevent the white-cast effect common with arrowroot-only formulas.
In Tooth Powder
Food-grade DE has mild abrasive properties that help remove surface stains from tooth enamel — gentler than many commercial whitening abrasives. Combined with baking soda, calcium carbonate, and a few drops of peppermint essential oil, it forms an effective natural tooth powder. Always use food-grade DE in oral formulations.
INCI name for cosmetic labelling: Diatomaceous earth is listed as Diatomaceous Earth or Diatomite on cosmetic ingredient lists. Always confirm the exact INCI specification with your supplier's SDS documentation and list it in descending order of concentration per the Consumer Goods (Cosmetics) Information Standard 2020.
Pest Control: How to Use DE Effectively
Used correctly, food-grade DE is one of the most effective non-toxic pest control tools available in Australia. It is approved for organic farming certification, leaves no chemical residue, and insects cannot develop resistance to it. Here's how to get the best results.
Application Guidelines
- Apply dry. DE only works as a desiccant and abrasive when dry. Wet DE loses its effectiveness completely (though it reactivates when it dries). Don't apply in rain or high humidity.
- Apply as a fine dusting, not a thick layer. Insects avoid walking through thick piles of DE. A fine, barely-visible dusting along skirting boards, entry points, and pest pathways is far more effective.
- Focus on entry points and pathways. Insects must walk through DE for it to work — target cracks, door frames, under appliances, and along walls rather than the middle of rooms.
- Leave undisturbed. Avoid vacuuming or mopping treated areas frequently. Reapply after cleaning, after rain in outdoor areas, or every 4–6 weeks as a preventive measure.
- For garden use: Dust on plant leaves early morning when dew helps DE adhere. Works on aphids, mites, thrips, and caterpillars. Reapply after rain. Avoid applying to flowers during bloom as it can harm beneficial pollinators.
- For grain storage: Mix thoroughly through dry grain at 50–100g per 100kg of grain. Store in airtight containers after treatment.
Important note for gardeners: While DE is non-toxic to most mammals and birds, it is not selective about which insects it harms. Avoid applying DE to flowering plants or areas where beneficial insects like bees and ladybirds are active — the physical mechanism affects all insects equally. Apply at dusk when pollinators are less active, or focus applications on soil level and stems rather than flowers and leaves.
Health, Wellness & Dietary Uses
Food-grade diatomaceous earth has a long history of use in traditional health practices and has attracted growing interest in the natural wellness community. While scientific evidence for some claimed benefits remains limited or preliminary, there are well-understood mechanisms behind several of its commonly cited applications.
Silica and Connective Tissue
Silicon is the second most abundant element in the Earth's crust and is found naturally in human connective tissue, cartilage, bone, skin, hair, and nails. Some research suggests that adequate dietary silicon supports collagen synthesis, bone density, and skin elasticity. Food-grade DE is approximately 85% amorphous silicon dioxide — the food-grade silica in DE is considered to be partially bioavailable, though research is ongoing on the exact mechanisms and quantities required.
Digestive Health Claims
Some proponents suggest that food-grade DE supports digestive health by adsorbing toxins, heavy metals, and harmful bacteria in the gut as it passes through the digestive tract. This is mechanistically plausible given DE's extraordinary surface area and adsorption capacity. However, robust clinical evidence specifically for DE is limited — most references come from agricultural use (parasite control in livestock) rather than human clinical trials. Always consult a healthcare professional before using DE as a dietary supplement.
Important health advisory: Food-grade DE is considered safe for consumption by regulatory bodies including FSANZ (Food Standards Australia New Zealand) as a food additive and anti-caking agent. However, large doses, prolonged consumption without medical guidance, and use as a substitute for medical treatment are not recommended. Always consult your GP, naturopath, or healthcare professional before using DE internally, particularly if you take prescription medications (DE may adsorb and reduce the absorption of some medications).
Safety Guidelines for Australian Users
Food-grade DE is one of the safest natural substances available for home and garden use when handled correctly. The primary safety consideration is managing inhalation of the fine dust during application.
- Always purchase food-grade DE for home, garden, cosmetic, and health applications. Never use pool-grade DE outside of pool filtration systems.
- Wear a dust mask or P2 respirator during application — DE is a fine, inhalable powder that can irritate the respiratory tract when disturbed. This applies to food-grade DE as well as pool-grade.
- Avoid applying on windy days to prevent dispersal into the air. Apply in calm conditions or lightly dampen the surface before application in dusty conditions.
- Keep children and pets away from the area during application and allow dust to settle before re-entry — typically 30–60 minutes.
- If DE contacts eyes, flush immediately with water for 15 minutes. Seek medical attention if irritation persists.
- When using DE as a dietary supplement, always start with a small amount (half a teaspoon in a full glass of water) and increase gradually. Drink plenty of water throughout the day. Consult a healthcare professional before use.
- Store in a sealed, moisture-free container in a cool, dry location. Moisture reduces effectiveness for pest control and can cause clumping.
- For cosmetic use, always use cosmetic or food-grade DE and include it in your product's INCI ingredient list.
Frequently Asked Questions
What is the difference between food-grade and pool-grade diatomaceous earth?
Food-grade DE contains less than 1% crystalline silica and is safe for human and animal consumption, household use, and cosmetic applications. Pool-grade DE has been heat-treated, converting amorphous silica to crystalline silica — making it highly dangerous to inhale and completely unsuitable for consumption, pets, gardens, or cosmetics. Always use food-grade DE for all home applications.
How does diatomaceous earth kill insects?
DE kills insects through physical mechanisms — not chemicals. The microscopic sharp edges of diatom silica pierce the waxy exoskeleton of insects, causing fatal dehydration. Because the mechanism is physical rather than chemical, insects cannot develop resistance to DE the way they do to chemical pesticides.
Is diatomaceous earth safe for pets and children?
Food-grade DE is generally safe around pets and children when used as directed. The primary concern is inhalation — always wear a dust mask during application, apply in calm conditions, and keep children and pets away until dust settles. Never use pool-grade DE around people or animals.
Can diatomaceous earth be used in cold process soap?
Yes — cosmetic-grade DE at 1–2 teaspoons per 500g of oils provides gentle exfoliation, a smooth creamy lather, and a soft after-feel. Disperse it in a carrier oil before adding at trace. Its fine particle size makes it suitable for facial soap formulations where harsher exfoliants would be too aggressive.
How do I store diatomaceous earth to maintain its effectiveness?
Store DE in a sealed, airtight container in a cool, dry place away from moisture. Moisture causes clumping and reduces effectiveness for pest control applications. Wet DE is temporarily inactive — it reactivates on drying. For long-term storage, a sealed bucket or drum in a dry shed or cool cupboard is ideal.
Does diatomaceous earth harm earthworms or soil biology?
When mixed into moist soil, DE does not significantly harm earthworms because the moist environment neutralises its desiccating mechanism. Applied on the soil surface in dry conditions it can affect surface-dwelling beneficial insects. When mixed into soil as an amendment, it generally has a neutral to positive effect on soil structure and has been used for decades in organic farming without reported harm to soil biology at recommended rates.
Shop Diatomaceous Earth
Food-grade diatomaceous earth — safe for home, garden, cosmetics, and livestock. Available now from Soapmaid Australia with full documentation.
Shop Diatomaceous Earth Food Grade · SDS Provided · Australian SupplierRelated Ingredients & Supplies
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Recipes & Lye Calculations: All recipes, formulations, usage rates, and SAP values published on this blog are provided as a general guide only. Always verify every lye calculation independently using the Soapmaid Lye Calculator before making any batch. SAP values can vary between oil batches, suppliers, and processing methods. Soapmaid Australia accepts no responsibility for any errors, omissions, or outcomes resulting from the use of recipes or calculations published on this site.
Safety & Chemicals: Soap making involves the use of sodium hydroxide (lye / caustic soda) and potassium hydroxide — both highly caustic substances capable of causing serious burns. Always wear appropriate personal protective equipment (PPE) including nitrile gloves, safety glasses, and protective clothing. Work in a well-ventilated area. Keep children and pets away from your workspace. Never use aluminium containers or utensils with lye. Store chemicals safely and in accordance with all applicable Australian state and federal regulations.
Health & Therapeutic Claims: Nothing published on this blog constitutes medical advice, and no information on this site should be used to diagnose, treat, prevent, or cure any health condition. Information about the wellness uses of diatomaceous earth is provided for general educational context only. Always consult a qualified healthcare professional before consuming diatomaceous earth or using it for therapeutic purposes. Diatomaceous earth may interact with some medications.
Cosmetic Compliance: Information regarding cosmetic ingredients, labelling, and regulation is provided for general educational purposes only and does not constitute legal or regulatory advice. Always verify current requirements directly with AICIS, the ACCC, and the TGA before selling cosmetic products commercially in Australia.
Skin & Allergy Sensitivity: Every individual's skin is different. Always perform a patch test before using any new formulation on a wider area of skin. If irritation or an adverse reaction occurs, discontinue use immediately and seek medical advice.
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