Testing acc. to VDA 230-205: Automotive Leather - Determination of loose grain effect
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Testing methods
Our test laboratory performs testing according to VDA 230-205 as an accredited test method to determine the loose grain effect of leather used for automotive interior trim. Both non-laminated and laminated leather can be tested. The method is applicable to non-laminated leather up to a thickness of approximately 2.0 mm and laminated leather composites up to a total thickness of approximately 5 mm.
The term loose grain effect describes visible wrinkling of the grain side when the leather is bent concavely. This effect can have different causes, including insufficient bonding of the grain layer to the underlying leather structure, a loose fibre structure within the leather, or additional strain introduced by a backing material laminated to the flesh side. The test therefore evaluates not only the extent of wrinkling but can also provide information about its cause.
Testing according to VDA 230-205
The leather is bent concavely over a half-cylinder (“Halpi”) with a defined radius, with the grain side facing outwards. The resulting wrinkle pattern is compared with photographic reference samples and assessed using a five-grade rating scale. Separate reference scales are provided for smooth, embossed and laminated leather.
Procedure A is used for non-laminated leather. Part of the flesh side is fixed with specified adhesive tape so that the wrinkling behaviour of the fixed and non-fixed areas can be compared directly. Evaluation is carried out in directions longitudinal and transverse to the backbone. Procedure B is intended for already laminated leather and uses a larger bending radius; two mutually perpendicular material directions are evaluated.
Applications of the test
VDA 230-205 is primarily used to assess automotive leather for undesirable wrinkles, waviness and other visible changes of the grain surface during bending. For non-laminated leather, the test can also be carried out non-destructively on complete hides for incoming or outgoing inspection.
A particular advantage of the method is the additional root-cause analysis described in the standard for specimens receiving a poor rating. Microscopic examination can help distinguish whether the grain layer separates from the underlying fibre structure, whether a loose leather fibre structure becomes apparent because of backing fixation, or whether the laminate itself contributes to wrinkle formation. The method therefore also has a direct connection with FILK's material failure analysis and expertise.
The test is included in numerous material specifications and, in modified form, is also applied to artificial leather, for example in DBL 1200, DBL 5310, BMW TL 9879076.6 for wrinkle formation of artificial-leather trilaminates, as well as BMW GS 93039 and BMW QV 11739234 using methods adapted from this procedure.
Related tests
For evaluating further properties of leather and flexible surface materials used in vehicle interiors, FILK also offers bending stiffness testing according to VDA 230-209, abrasion testing according to VDA 230-211, and determination of soiling and cleaning properties according to VDA 230-212.
Here you will also find an overview of our range of VDA tests and specifications.
