Isopropyl Alcohol vs Methylated Spirit: What's the Difference?

Pioma Chemtech Inc.

Oct 1

4 min read

Isopropyl alcohol (IPA) is a single chemical — 2-propanol — while methylated spirit is ethanol with denaturants added to make it undrinkable. They are different alcohols with different properties, different smells, different best uses, and different regulatory treatment. The confusion is understandable because both are sold as "spirit" or "rubbing alcohol" in different markets, but they are not interchangeable.

This guide explains what each one actually is and where each one wins.

The short version

Attribute	Isopropyl alcohol (IPA)	Methylated spirit
Chemistry	Isopropanol (2-propanol)	Ethanol + denaturants
Common concentrations	70%, 99%	90–99% (denatured)
Smell	Sharp, "rubbing alcohol"	Ethanol smell + chemical edge
Skin use	Yes (70%)	Generally no — denaturants can irritate
Surface cleaning	Yes	Yes
Electronics cleaning	Yes (99%)	Sometimes — leaves residue from denaturants
Burns clean?	Yes, blue flame	Yes, yellow-orange flame
Drinkable?	No, toxic	No, deliberately made toxic
Indian retail availability	Common in pharmacies	Common in hardware/paint stores

Isopropyl alcohol — single molecule

Isopropyl alcohol is a single chemical compound. It is colourless, miscible with water, evaporates fast, and dissolves a wide range of substances. In medicine and electronics, it is the dominant alcohol because it is consistent (one chemical), residue-free at 99%, and reliably effective as a disinfectant at 70%.

Common uses:

Skin antisepsis at 70% (injection prep, swabs).
Surface disinfection.
Electronics cleaning at 99% (PCB boards, contacts, lenses).
Laboratory glassware rinse.
Vehicle and industrial cleaning.

Pharmacopoeial-grade IPA (IP) is the standard for medical use.

Methylated spirit — denatured ethanol

Methylated spirit is ethanol — the same chemical you find in beverages — but deliberately made undrinkable by adding denaturants. The denaturants vary by country and use but commonly include methanol, methyl isobutyl ketone, denatonium benzoate (an extremely bitter compound), or pyridine.

The purpose is regulatory: ethanol attracts heavy duty as a beverage but methylated spirit can be sold for industrial, fuel, and cleaning use at much lower cost.

Common uses:

Cleaning paintbrushes and tools.
Lacquer thinning.
Polishing furniture (French polish).
Camping stove fuel.
Industrial degreasing.
Some general surface cleaning.

Because of the denaturants, methylated spirit is not normally used for skin antisepsis or for any application where residue matters or where skin contact is significant.

Why the names are confusing

In India and many other markets, several similar-sounding names exist:

Surgical spirit — typically ethanol or denatured ethanol with castor oil and other ingredients per pharmacopoeial formulation. Used for skin.
Rectified spirit — high-purity ethanol (~95%), drinkable in some contexts (industrial alcohol licensing applies).
Methylated spirit — denatured ethanol, not drinkable.
Isopropyl alcohol / rubbing alcohol — isopropanol.

The names are not interchangeable, even when they sound related. Always read the label.

Where IPA wins

Medical skin antisepsis — IPA 70% is the standard. Methylated spirit's denaturants can irritate skin.
Electronics cleaning — IPA 99% evaporates clean. Methylated spirit usually leaves residue from denaturants and additives.
Pharmaceutical and laboratory glassware — IPA's single-chemical purity matters.
Sensor and probe cleaning — IPA leaves no residue.
Surface disinfection where the contact is brief — IPA 70% is fast and effective.

Where methylated spirit wins

Removing paint and varnish — denaturants help dissolve coatings.
Cleaning paint brushes — strong solvency, cheap.
Polishing wood (French polish) — traditional use; specific evaporation profile suits the technique.
Industrial degreasing where cost matters and residue doesn't — cheaper per litre.
Camp stove fuel — sold as "burning spirit" in some markets.

Safety considerations for both

Both are highly flammable. Vapours form ignitable mixtures with air.
Both are toxic to drink — IPA inherently, methylated spirit by added denaturants. Ingestion can be very dangerous.
Both can cause skin dryness on repeated contact.
Both should be stored in cool, ventilated spaces, away from ignition sources.
Both should be kept out of reach of children — and never decanted into food bottles.

Can I substitute one for the other?

For most use cases, no:

Don't substitute methylated spirit for IPA in skin antisepsis. The denaturants can cause skin irritation.
Don't substitute methylated spirit for IPA on electronics. Residues can damage sensitive components.
Don't substitute IPA for methylated spirit in paint thinning. IPA can work for some thinning but is not the standard solvent.
Don't substitute either for surgical spirit in medical use without checking pharmacopoeial compliance.

The chemistries are different enough that the result will not be the same.

In an Indian retail context

Pharmacies sell IPA 70% (often as "rubbing alcohol" or with IP marking) and surgical spirit.
Hardware and paint stores sell methylated spirit and rectified spirit for industrial/cleaning use.
Laboratory suppliers sell IPA 99% in larger packs.

If a buyer asks for "spirit", ask which one — confusion between the three is common.

Frequently Asked Questions

Can I use methylated spirit on a cut?

No. Methylated spirit's denaturants can irritate skin and the wound. Use a labelled antiseptic (such as povidone-iodine, dilute IPA, or chlorhexidine) per product instructions.

Is methylated spirit cheaper than IPA?

Usually yes, especially in larger packs, because of the regulatory cost structure around ethanol. But the choice should be driven by use, not just price.

Which is better for cleaning a phone screen?

IPA, typically 70% on a soft cloth. Methylated spirit's additives can damage screen coatings.

Can I use IPA to thin paint?

For some paint types, partially — but methylated spirit (or the specific thinner recommended by the paint manufacturer) is usually a better choice.

Why is methylated spirit coloured?

Many methylated spirit products have a purple or blue dye added so they can be visually distinguished from drinkable alcohol. This is part of the denaturing process in some markets.

Are both flammable?

Yes — both are flammable. Store away from heat and ignition sources. Methylated spirit burns with a yellow-orange flame; IPA with a slightly bluer flame.

Is surgical spirit the same as methylated spirit?

No. Surgical spirit is a pharmacopoeial-grade formulation, typically ethanol with castor oil and other ingredients to be skin-friendly. Methylated spirit is for industrial/cleaning use and contains skin-irritating denaturants.

For distributors and procurement teams sourcing IPA 70%/99% or surgical spirit, Pioma Chemtech, a specialty chemical manufacturer based in India, is available for commercial supply — please get in touch to discuss requirements.