Ingredient review
Sodium Metasilicate
INCI: Sodium Metasilicate
Sodium Metasilicate is an effective pH adjuster but can be highly irritating, especially in leave-on products or for sensitive skin.
In plain English
Sodium Metasilicate is a mineral-based ingredient that helps control the acidity (pH) of a product. Think of it like a tiny chemistry helper that keeps the formula stable. However, because it's quite alkaline (the opposite of acidic), it can be harsh on skin, potentially causing dryness or irritation if used too strong or left on the skin too long. It's more common in rinse-off products like cleansers or soaps.
Review score
Safety, usefulness, and evidence
Useful in the right context, but not low-maintenance
The evidence base is useful, but some claims depend heavily on the formula.
Main practical flags: irritation is high; clogging risk is low.
- Source
- synthetic
- Evidence
- moderate
- Irritation
- high
- Clogging risk
- low
Quick decision guide
Read the cautions before using
Sodium Metasilicate can be useful, but watch for high irritation potential.
Plain-English read
Treat this as a practical screening step before you compare products that contain this ingredient.
- Step 1Start with the score, then check the irritation and clogging risk before judging Sodium Metasilicate.
- Step 2Use the "Best for" and "Use caution if" sections to match the ingredient to your skin, not just to a marketing claim.
- Step 3If a product stings, breaks you out, or worsens irritation, judge the finished formula and stop using it even if the ingredient scores well.
Score terms in plain English
Irritation risk
highMore likely to cause dryness, stinging, peeling, or reactivity if used too aggressively.
Clogging risk
lowLess likely to feel heavy or contribute to clogged pores for most skin types.
Evidence level
moderateThere is useful support, but formula details and claim strength still matter.
What it is
Sodium Metasilicate is an inorganic salt derived from silica (sand) and sodium carbonate (soda ash). In cosmetics, it's a synthetic ingredient used to adjust and stabilize the pH of a formula, making it more alkaline.
How it works
In a cosmetic product, Sodium Metasilicate acts as a buffering agent, meaning it helps maintain a consistent pH level. It also has mild cleansing and emulsifying properties, helping to mix oil and water. Its high alkalinity can help break down oils and dirt, which is why it's sometimes used in cleansers, but this same property can strip the skin's natural protective barrier.
Pros
Effective pH stabilizer
Helps keep the product's pH consistent, which is important for formula integrity and performance.
Boosts cleansing power
Its alkalinity helps break down oils and dirt, making it useful in soaps and cleansers for a thorough clean.
Cons and cautions
High irritation risk
Can cause stinging, redness, and dryness, especially for sensitive or reactive skin types. It's best avoided in leave-on products.
Can strip the skin barrier
Its high pH can disrupt the skin's natural acid mantle, leading to increased transepidermal water loss (TEWL) and a compromised barrier.
Best for
- People with oily, non-sensitive skin looking for a deep cleanse
- Those using rinse-off products like bar soaps or facial washes
Use caution if
- Individuals with sensitive, dry, or compromised skin
- Anyone using leave-on products (creams, serums) where this ingredient is present
Usage tips
Safety summary
Sodium Metasilicate is considered safe for use in rinse-off cosmetics at low concentrations, but it carries a high risk of skin irritation and dryness. It is not recommended for sensitive skin or leave-on products. Always patch test and follow product instructions.
Research notes
Research indicates that Sodium Metasilicate can cause skin irritation and corrosion at high concentrations. The Cosmetic Ingredient Review (CIR) panel has evaluated it and concluded it is safe for use in rinse-off products when formulated to be non-irritating. There is limited evidence for any skincare benefits beyond pH adjustment and cleansing.
Common label clues
- Typical concentration
- Typically used at very low concentrations (under 1%)
- Regulatory status
- Approved for use in cosmetics in the EU and US, but concentration limits may apply. The Cosmetic Ingredient Review (CIR) panel has noted potential for irritation at high concentrations.
- Common uses
- Cleansers, Soaps, Hair products
- Environmental note
- Sodium Metasilicate is a synthetic mineral salt. Its production involves mining and processing of silica, which has a moderate environmental footprint. It is biodegradable but can contribute to alkalinity in wastewater.
Good to know
- Sodium Metasilicate is different from the more common Sodium Silicate, which is used as a corrosion inhibitor.
- It is often found in industrial cleaners and is much more diluted in cosmetic formulas.
Common questions
What is Sodium Metasilicate in beauty products?
Sodium Metasilicate is a mineral-based ingredient that helps control the acidity (pH) of a product. Think of it like a tiny chemistry helper that keeps the formula stable. However, because it's quite alkaline (the opposite of acidic), it can be harsh on skin, potentially causing dryness or irritation if used too strong or left on the skin too long. It's more common in rinse-off products like cleansers or soaps.
What does Sodium Metasilicate do in a beauty product?
In a cosmetic product, Sodium Metasilicate acts as a buffering agent, meaning it helps maintain a consistent pH level. It also has mild cleansing and emulsifying properties, helping to mix oil and water. Its high alkalinity can help break down oils and dirt, which is why it's sometimes used in cleansers, but this same property can strip the skin's natural protective barrier.
Is Sodium Metasilicate safe for most people?
Sodium Metasilicate is considered safe for use in rinse-off cosmetics at low concentrations, but it carries a high risk of skin irritation and dryness. It is not recommended for sensitive skin or leave-on products. Always patch test and follow product instructions.
Who should be careful with Sodium Metasilicate?
Individuals with sensitive, dry, or compromised skin Anyone using leave-on products (creams, serums) where this ingredient is present
Research sources
Ingredient reviews are educational and are not medical advice. Patch test new products and ask a licensed clinician about persistent irritation, allergies, pregnancy-specific questions, or diagnosed skin conditions.