How does n-butyl acetate's evaporation compare with ethyl acetate?
n-Butyl acetate boils at 126 C and is the usual reference solvent for relative evaporation rate (set to 1); ethyl acetate evaporates approximately four times faster. That slower release gives a wet film more time to flow and level, which is why n-butyl acetate suits coatings, lacquers, inks and thinners, while ethyl acetate suits faster release. The ratios are approximate general knowledge.
- A slower ester gives a wet film more time to flow and level, which is why n-butyl acetate appears in automotive and industrial coatings, lacquers, printing inks and thinners.
- Our n-butyl acetate (CAS 123-86-4, 99.5 % w/w min, water 0.10 % max, grade per TDS: ASTM D4615) is supplied from Chennai by bulk road tanker and HDPE or MS drums.
- Blend design is the formulator's decision. This guide gives the vocabulary and the checks, not a recipe.
Why evaporation speed matters in a coating
A solvent in a coating or lacquer has a job to do and then has to leave. While it is in the wet film it keeps the resin dissolved and the viscosity workable, so the film can flow out, level and wet the surface. When it evaporates the film hardens. If the solvent leaves too fast, the surface can skin over before the film has levelled, leaving brush marks, orange peel or poor gloss. Fast evaporation can also cool the surface enough to pull moisture out of the air, which shows up as milky 'blushing' in some lacquers. If the solvent leaves too slowly, the film stays soft, collects dust and sags on vertical surfaces.
Formulators manage this by blending: a fast solvent for quick set, a medium one for the working period, a slow one to finish the flow. n-Butyl acetate boils higher than ethyl acetate and evaporates more slowly, so it is typically used for the working and finishing stages of that blend. Everything in this section is general coatings knowledge, not an SPC specification.
Relative evaporation rate: what the scale means
Evaporation rate is usually quoted relative to n-butyl acetate, which is set to 1. A number above 1 evaporates faster than n-butyl acetate; a number below 1 evaporates more slowly. Boiling point gives a rough guide to the order, although it is not the whole story because molecular interactions and vapour pressure also play a part. Our SDS gives the evaporation rate as Moderate relative to diethyl ether = 1, which is a different reference from the n-butyl acetate = 1 scale used here. We do not state a numeric evaporation value for our own material.
| Solvent | Approx. boiling point |
|---|---|
| Acetone | approx. 56 C |
| Ethyl acetate | approx. 77 C |
| Isopropyl alcohol | approx. 82 C |
| Toluene | approx. 111 C |
| n-Butyl acetate | 126 C (SDS) |
Source: the n-butyl acetate boiling point is from our Safety Data Sheet. All other rows are approximate general chemistry knowledge. Ethyl acetate evaporates approximately four times faster than n-butyl acetate on the n-butyl acetate = 1 scale (also approximate). Use your supplier's data or your own tests for formulation decisions.
What our safety data adds
Our SDS for n-butyl acetate gives physical properties that matter for plant design as well as formulation:
| Property | Value (SDS section 9) |
|---|---|
| Boiling point | 126 C |
| Relative density | 0.88 at 20 C |
| Vapour pressure | 15 hPa at 20 C |
| Vapour density (air = 1) | 4.0 |
| Flammability limits | LEL 1.2 % v/v, UEL 7.5 % v/v |
| Auto-ignition temperature | 421 C |
| Solubility in water | Slightly soluble |
Source: Safety Data Sheet for Butyl Acetate, section 9.
Two practical points follow. Vapour density 4.0 means the vapour is heavier than air and collects low, so ventilation and ignition control apply at floor level. And the flammability range is wide enough that grounding and bonding during transfer, plus explosion-proof equipment, are standard precautions. The classification is Flam. Liq. 3 (H226), UN 1123, Class 3, packing group III. Read the downloadable SDS before first receipt.
Where n-butyl acetate is used
Coatings and lacquers
Our product data lists paints, coatings and lacquers, and automotive and industrial coating formulations, as applications. Here the slower evaporation supports flow and levelling. See our Paints / Coating industry page.
Printing inks
Printing-ink formulations use n-butyl acetate as a solvent component. See the Inks / Printing Inks page; butyl acetate is also listed for flexo and roto printing.
Thinners
Thinner blenders combine fast, medium and slow solvents to suit different resin systems and shop conditions. See our Thinner page.
Adhesives
The SDS intended use covers solvent for coatings, inks and adhesives, for industrial and professional use only.
Choosing between n-butyl acetate and ethyl acetate
| Question | Leans towards n-butyl acetate | Leans towards ethyl acetate |
|---|---|---|
| Is flow and levelling the main problem? | Yes, slower release helps | No |
| Do you need fast set or quick drying? | No | Yes |
| Is blushing a risk in humid conditions? | Slower solvent reduces surface cooling | Faster solvent raises the risk |
| Is the blend a thinner with several roles? | Often the slower component | Often the faster component |
Source: general coatings knowledge, not an SPC specification. We supply both; see the Ethyl Acetate page.
Specification points that matter to a formulator
- Purity, 99.5 % w/w min. Residual alcohol and other organics shift the evaporation profile (general knowledge).
- Water, 0.10 % w/w max. Water is a concern in moisture-sensitive systems such as two-pack polyurethanes, where it competes with the intended reaction. This is general coatings knowledge.
- Acidity as acetic acid, 0.01 % w/w max. Low acidity protects acid-sensitive pigments and resins. This is general coatings knowledge.
- Colour, 10 APHA max. Matters for clear and light-coloured finishes (general knowledge).
The limits are from our TDS, SPC-TDS-EST-003. The batch Certificate of Analysis supplied with every delivery gives the result for your lot.
Grade, sourcing and enquiry
Our n-butyl acetate, grade per TDS: ASTM D4615 (TDS title: Solvent Grade). It is a solvent-grade material, not food or pharma grade. We are a trader, importer and distributor, not a manufacturer. Makers, packs and the enquiry steps are on the butyl acetate product page; we quote within 4 working hours.
Related
Partner solvents in a blend: Toluene and IPA. Supply from Chennai: bulk solvent supply.
This guide looks only at evaporation speed and film flow in coatings. For a three-way comparison with acetone, read ethyl acetate vs butyl acetate vs acetone; for cleaning and thinning choices, read acetone vs IPA vs ethyl acetate.
Frequently asked questions
Is n-butyl acetate slower than ethyl acetate?
Yes. It boils higher and is the reference solvent for the relative evaporation scale; ethyl acetate evaporates approximately four times faster. These ratios are approximate general knowledge.
Why do coatings use a slow solvent at all?
To give the wet film time to flow and level before it sets, which improves surface finish.
Is the grade suitable for food or pharma use?
No. It is a solvent-grade material for coatings, inks and thinners, not food or pharma grade.