Ash | EUROLAB

What Is Ash Content?

Ash determination is burning the sample at high temperature to remove its organic portion and weighing the remaining inorganic residue. The residue represents the filler, reinforcement and inorganic additives in the material.

Purpose of Ash Content

The purpose is to verify the compound's filler ratio and monitor consistency between batches. In glass-fibre-reinforced materials, reinforcement ratio directly determines mechanical properties.

Which Products Is Ash Content Applied To?

Glass-fibre-reinforced plastics
Mineral-filled compounds
Cable insulation materials
Recycled plastics
Rubber compounds

In Which Sectors Is Ash Content Used?

PlasticsPackagingAutomotiveElectronicsConstruction

Standards Related to Ash Content

ISO 3451-1 (determination of ash in plastics — general methods)
ISO 3451-4 (determination of ash in polyamides)
ASTM D5630 (ash content in plastics)
ISO 1172 (loss on ignition in glass-fibre-reinforced plastics)

Ash Content Conditions

combustion temperature: Temperature given by the standard according to the material
Kroze: Porcelain or platinum; brought to constant weighing
Time: until constant weight is reached
Cooling: In the desiccator, without moisture

Equipment for Ash Content

Ash furnace (muffle furnace)
Analytical balance
Porcelain or platinum crucibles
Desiccator
Crucible tongs and protective equipment

Sample Requirements for Ash Content

The sample must be taken so as to represent the batch or production run.
Sample description, material type, and production direction if any, must be stated.
The standard to be applied and any customer specification must be provided together with the sample.
The test may be destructive; the required number of samples must be confirmed in advance.
Surfaces that will be tested must be protected during transport.

Duration of Ash Content

The analysis generally takes one to two working days due to burning and reaching constant mass.

Ash Content Procedure

1The crucible is brought to constant mass and weighed.
2The sample is weighed and placed in the crucible.
3The crucible is burned in the furnace at the defined temperature.
4Burning is repeated until constant mass is reached.
5The crucible is cooled in the desiccator.
6The residue is weighed.
7Ash percentage is calculated.

Ash Content Acceptance Criteria

The method standard defines how the test is performed, not what the result must be. The acceptance limit comes from the material or product standard, the customer specification, or the relevant regulation; this page therefore does not give a numerical limit.

Evaluation of Results

The result is compared against the filler ratio in the raw material specification. Some fillers can decompose at the burning temperature (e.g. carbonates); in that case the raw ash value requires correction and this is stated in the report.

Ash Content Report

Sample description, material/product information, and batch number if any
Sample preparation method and conditioning conditions
Standard and test conditions applied
Instrument used and calibration status
Measurement results and units
Measurement uncertainty (if requested)
A statement that the result applies only to the specimen submitted for testing

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Harmonised standards applied according to the product family
EU 765/2008 (market surveillance and accreditation framework)
Relevant product regulations and customer specifications

Plastics Testing — What Does This Testing Field Cover?

The section below describes the field that the Ash Content test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Plastics testing determines the mechanical, thermal and burning behaviour of a polymer material. Unlike metals, plastics are VISCOELASTIC: their behaviour depends on loading rate, temperature and moisture. The same material therefore gives different results under different conditions, and the test conditions are an inseparable part of the result.

The practical consequence of viscoelasticity is this: a plastic part continues to deform over time under a constant load (creep) and the stress it carries at constant deformation falls over time (stress relaxation). A screwed joint loosens, a clamp loses its clamping force, a shelf sags over time. A short-term tensile test does not show this behaviour; a long-term test or an accelerated model is needed.

Thermal behaviour is the second main axis. Melt flow rate indicates the processability of the material and lot-to-lot consistency; heat deflection temperature and the Vicat softening point give a rough limit for service temperature. Thermal analysis (DSC, TGA, DMA) reveals the identity of the material: glass transition temperature, melting behaviour, crystallinity, filler content and decomposition temperature.

Burning behaviour is the third axis and ties directly into product standards. The UL 94 class and the limiting oxygen index are written into the material data sheet; a particular class is required for the housing of an electrical appliance, while a different classification system applies to a construction product.

Ageing is the most frequently skipped part of the field. Plastics degrade under UV, heat, moisture and oxygen: colour changes, the surface cracks, impact strength falls. For a part intended for outdoor use, what matters is not its values on day one but its values after ageing. Xenon arc and fluorescent UV equipment accelerate this degradation and allow comparison.

The output of this family is usually written into the material data sheet, and product standards refer to that sheet. But there can be a difference between the data sheet value and the behaviour of the actual part: orientation formed during moulding, weld lines and internal stresses make the part behave differently from the specimen.

The use of recycled content has added a new question to the field. Recycled resin varies from lot to lot; mechanical properties, colour and burning behaviour can shift between batches. For a manufacturer using recycled material, incoming material control is therefore not a choice but a necessity.

Method groups in this field

Mechanical
Tension, compression, bending, Charpy and Izod impact, hardness (Shore), creep and environmental stress cracking.
Thermal
Melt flow index (MFI), heat deflection temperature (HDT), Vicat softening temperature, linear thermal expansion.
Thermal analysis
Transition temperatures and crystallinity by DSC, composition and decomposition by TGA, dynamic mechanical behaviour by DMA.
Burning
UL 94 classification, limiting oxygen index (LOI), glow wire and needle flame tests.
Ageing
Accelerated ageing by xenon arc and fluorescent UV, hot air ageing, humidity and condensation.
Physical
Density, water absorption, ash content, gas and water vapour permeability of films and sheets.

Commonly confused in this field

A plastics result without a stated test rate and temperature cannot be interpreted; viscoelastic behaviour depends on these parameters.
A specimen result does not transfer directly to the actual part; moulding orientation and weld lines are decisive.
HDT and Vicat values are NOT service temperatures; they are a rough indication of an upper limit and do not apply under load.
The UL 94 class depends on thickness; a different wall thickness requires re-verification.
For moisture-absorbing polymers (such as polyamide), results are misleading unless conditioning is carried out.
ASTM D638 and ISO 527 results are not directly equivalent; the specimen geometries and rate definitions differ.

Which decisions these results support

Material selection and supplier approval
Meeting the flammability and thermal requirements of the product standard
Verifying the use of recycled content and lot control
Moulding process control and lot consistency
Demonstrating ageing resistance for outdoor use

Related Tests

Frequently Asked Questions About Ash Content

Is the ash ratio directly the glass fibre ratio?

Approximately. If the material also contains other inorganic additives, ash is their sum. If only the glass fibre ratio is wanted, the ISO 1172 approach and a known formulation are required.

Is carbon black visible in the ash?

No. Carbon black burns off during ignition and does not remain in the ash; it is therefore determined by a separate method (pyrolysis).