HARD-WATER CHELATOR
Etidronic Acid
- hard-water chelator
A chelator that binds hard-water minerals and stabilises the formula.
- products in our library
- 8
- of researched products
- 0.2%
- on the label, in our conditioners
- usually #30
- most common in
- Conditioner
- in water
- Water-soluble
At a glance
Four named levels, read from this ingredient’s chemical class, its charge, its solubility, or where it sits on the labels we have. More dots means more of the property named — never “better”.
How much of it is left on hair between washes.
What it takes to get it off the hair again.
The housekeeping this class does.
Where it sits on the labels we have, in the category it appears in most.
| Property | Level | Out of |
|---|---|---|
| Buildup risk | Low | 1 of 5 |
| Rinse-out behaviour | Rinses clean | 5 of 5 |
| Job | Ties up hard-water minerals | 4 of 5 |
| Prominence | Secondary | 2 of 5 |
What it does for a formula
What Etidronic Acid does
The general function first, then how the role changes by product type where we have researched it.
Stops calcium and iron in tap water dulling a wash.
Water alone removes it, so it does not accumulate between washes.
Charge
Charge is not recorded for this ingredient.
Solubility
Rinses out with water alone — it does not accumulate on hair between washes.
Where it appears
Where it appears
One row per product category in our library: how many products list it, what share of that category that is, and where it typically sits on the label.
| Product type | How common | Typical position on label ? |
|---|---|---|
Conditioner
4 products
|
secondary · #30 | |
Leave-in
1 product
|
secondary · #28 | |
Mask / treatment
1 product
|
secondary · #10 | |
Styler: smoothing cream
1 product
|
secondary · #29 | |
Styler: volumizer
1 product
|
secondary · #9 |
| Product type | Products | Share of category | Median position | Earliest position | Band |
|---|---|---|---|---|---|
| Conditioner | 4 | 1% | 30 | 25 | secondary |
| Leave-in | 1 | 0% | 28 | 28 | secondary |
| Mask / treatment | 1 | 0% | 10 | 10 | secondary |
| Styler: smoothing cream | 1 | 2% | 29 | 29 | secondary |
| Styler: volumizer | 1 | 2% | 9 | 9 | secondary |
No product-type differences have been researched yet — the reading below is computed from where it sits on the labels in our library.
Position footprint
Every listing in our library, by position on the label.
| Positions | Zone | Listings |
|---|---|---|
| 1-3 | Leading | 0 |
| 4-8 | Supporting | 0 |
| 9-15 | Secondary | 2 |
| 16-25 | Lower | 2 |
| 26+ | Trace | 4 |
How to read this
US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order.
So position tells you about relative amount only above that line, and we never convert a position into a percentage.
Who should pay attention
Conditional formulation guidance, scoped to a hair condition and to the positions where it is meaningful. It is not a conclusion about any finished product, and not a conclusion about you.
Binds the calcium and magnesium in hard water, which is what stops mineral deposits accumulating on the strand wash after wash.
Copper and iron carried in tap water deposit on the strand and read as a dull, warm cast on gray or light hair. A chelator holds those metals in solution so the wash carries them off.
Read from this ingredient’s chemical class. Where we have researched the ingredient itself, that reading replaces the class one.
Why it matters to shoppers
What this ingredient is evidence of, what it is not evidence of, and what our own method can and cannot tell you.
- a formula built for hard water
- a rinse-clean feel
- a routine that does not build up
- gray or light hair to stay cool rather than warm
- an exact safety score — we do not publish one, for any ingredient
- how a finished product performs by itself — that is the whole formula, not one line of it
- the exact percentage in a bottle — label position never converts into a number
- a secondary chelator, listed below the main ingredients in our conditioners
- it was on the label of every product we counted — we read printed ingredient lists, not marketing copy
- that a product is right or wrong for you
We do not publish safety scores or hazard grades. Where a regulator has published a restriction or a use condition, we state it and cite it; otherwise we describe what the ingredient does and stop.
Commonly paired with
Ingredients that appear alongside this one most often in our library. Near-universal ingredients are excluded — they pair with everything and tell you nothing.
- Cetrimonium Chloride · 8
- Tocopherol · 6
- Propylene Glycol · 5
- C11-15 Pareth-7 · 4
- Trideceth-12 · 4
- Propanediol · 4
- Butylene Glycol · 4
- Butyrospermum Parkii (Shea) Butter · 4
- Disodium EDTA · 4
- Cetyl Alcohol · 4
The number beside a name is how many products in our library list both.
These ingredients tend to appear together to improve feel after rinsing, deliver a stated effect, and carry the formula and let it dry.
Found in these products
The most prominent placements first. The badge is the position on that product’s own ingredient list.
Paul Mitchell · Styler
Awapuhi Wild Ginger HydroMist Blowout Spray
#9 on the label · $5.39/oz
IGK · Mask / treatment
Paid In Full High Gloss Intense Repair Treatment
#10 on the label
amika · Conditioner
Bust Your Brass Cool Blonde Strength Repair Conditioner
#25 on the label · $2.72/oz
amika · Conditioner
The Kure Strength Repair Conditioner
#25 on the label · $3.04/oz
Aunt Jackie's · Leave-in
Transform! Hydrating Leave-in Conditioner
#28 on the label · $0.60/oz
OLAPLEX · Styler
No.6 Bond Smoother Frizz Control Styling Hair Cream
#29 on the label · $15.14/oz
Kirkland Signature · Conditioner
Moisture Conditioner
#35 on the label · $0.36/oz
Olaplex · Conditioner
No.5 Bond Maintenance Conditioner
#41 on the label · $4.00/oz
Identity
What this entry is, and what our references call it.
No public-domain structure depiction is available for this entry.
Etidronic Acid
- etidronic acid
For your hair?
Whether Etidronic Acid matters for your hair depends on your hair.
8 products in our library list itWhat this ingredient does, and where it sits on the labels we have researched.
A verdict on any product that contains it, and never a safety grade.
We do not physically test your hair. Everything above is read from the ingredient lists in our library and from published references — the consultation is what turns it into a plan.
References
Seed entry — sourcing in progress Written from our reference work; primary sourcing is still being attached.
No published source is attached to this entry yet.
How this page was made
- Every number above is counted from the ingredient lists in our own product library — 8 of 3889 researched products list this ingredient. Nothing on this page is written per ingredient.
- The dots are named levels read from an ingredient’s chemical class, charge, solubility, or where it sits on the labels we have — never a score.
- US labelling rules put ingredients above 1% in descending order of amount; below 1% they may be listed in any order. Position tells you about relative amount only above that line, and we never convert a position into a percentage.
- The prominence bands (leading, supporting, secondary) are the same ones the product pages use to read a single label, applied here to the median position across a category.
- We do not publish safety scores or hazard grades. Where a regulator has published a restriction or a use condition, we state it and cite it; otherwise we describe what the ingredient does and stop.
- Identifiers and references appear only when a published source is attached to this entry; where none is, the row is simply absent rather than filled in.
- This is cosmetic information, not medical advice, and nothing here diagnoses or treats a health condition.
- Entry last updated 2026-08-28. Product-page methodology: the product library.