Understanding Gum Arabic Mesh and Particle Size

“Mesh” is not a universal particle diameter. It refers to a sieve system, and the relationship between mesh count and aperture depends on the governing standard and sieve construction. A defensible gum arabic specification uses a named method and aperture in micrometres.

Why “80 mesh powder” is incomplete

The phrase does not tell a buyer:

which sieve standard or series applies;
the nominal aperture;
whether the claim means 90%, 95% or 100% passing;
what is retained on a coarser or finer sieve;
sample mass, sieving time, equipment or endpoint;
whether the powder is agglomerated or conditioned before testing.

Two suppliers can therefore use the same mesh label for distributions that are not equivalent.

A clearer sieve specification

Write a requirement in this structure:

Not less than X% passing a stated aperture in µm and not more than Y% passing or retained at a second stated aperture, tested using the named sieve standard and agreed method.

Use values selected for your process; do not copy placeholders from an article. A two-point or multi-sieve distribution usually says more than one pass limit.

ISO 3310-1 specifies technical requirements and testing for metal-wire test sieves from 125 mm down to 20 µm. ASTM E11 is a separate standard for woven-wire sieve cloth and test sieves. Name the one your laboratory uses.

When laser diffraction is used

Instrumental particle-size reports may present D10, D50 and D90 values. These are distribution percentiles, but results still depend on dispersion method, optical assumptions and instrument settings.

A useful report identifies:

instrument and analysis method;
dry or wet dispersion and dispersant;
sample preparation and obscuration range;
whether results are volume-, number- or surface-weighted;
repeatability and treatment of agglomerates.

Do not treat laser and sieve results as interchangeable without a demonstrated correlation.

Finer is not automatically better

Reducing particle size can affect dusting, cohesion, flow, bag discharge and wetting. Very fine powder added rapidly to water may form lumps because the outer surface hydrates before the interior wets. Published work on gum arabic powder found particle size influenced flowability and dissolution behaviour; smaller did not automatically mean faster dissolution.

Choose the distribution that works with the feeder, dust controls, mixing energy, addition sequence and required preparation time.

Trial and release controls

Ask whether particle size is tested per lot, periodically or only during product development. Agree the release method, rounding rules and what happens to oversize rework. Trial samples should represent routine particle control, not a specially sieved laboratory portion.

Our gum arabic powder page covers available commercial-form discussions. Include your aperture, method and pass/retain limits in a specification-led RFQ.