What Is UV?
UV aging test is performed in which the sample is exposed to radiation produced by fluorescent UV lamps along with defined temperature and condensation/water spray cycles; It is an experiment in which color, brightness and mechanical property changes are monitored.
Purpose of UV
The aim is to comparatively evaluate the degradation of the material under the influence of light and moisture under accelerated conditions.
Which Products Is UV Applied To?
- Outdoor plastic parts
- Paints and coatings
- Textiles and coated fabrics
- Rubber and elastomer profiles
In Which Sectors Is UV Used?
Standards Related to UV
- ISO 4892-3
- ASTM G154fluorescent UV accelerated aging test
- ASTM D4329
- ASTM G151 (genel gereksinimler)
UV Conditions
- Lamp type
- Standard-defined fluorescent UV lamps such as UVA-340 or UVB-313
- Radiation
- Set and monitored in W/m²·nm at defined wavelength
- Cycle
- Alternating periods of light and condensation/water spraying
- Temperature
- Identified and recorded as black panel temperature
Equipment for UV
- Fluorescent UV weathering chamber
- Irradiance measurement and control system
- Siyah panel termometresi
- Colorimeter, gloss meter and tensile device
Sample Requirements for UV
- Sample surface should be representative of the final product
- Initial colour, gloss and mechanical values should be recorded
- Sample position should be rotated within the cabin
- Control samples should be kept for comparison
Duration of UV
2 weeks to several months, depending on the exposure time defined in the specification.
UV Procedure
- 1Initial measurements are taken.
- 2Lamp type, irradiance and cycle are selected.
- 3Specimens are placed in the chamber.
- 4Exposure is maintained for the defined duration.
- 5Interim measurements are taken.
- 6Colour, gloss and mechanical change are evaluated.
UV Acceptance Criteria
Acceptance criteria are given in the specification: color difference, loss of gloss and loss of mechanical properties remain below the limit at the end of defined exposure.
Evaluation of Results
UVB-313 lamps contain short wavelengths not found in natural sunlight and create unrealistic degradation of some materials; Whichever lamp the material standard requires should be used. The number of accelerated hours cannot be converted to years of natural exposure.
UV Report
- Applied standard and lamp type
- Irradiance level and cycle program
- Black panel temperature
- Exposure duration
- Before/after measurements and evaluation
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 authorisationsRelated Regulations
- Product standards and OEM specifications
Paint and Coating Testing — What Does This Testing Field Cover?
The section below describes the field that the UV 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.
Paint and coating testing measures the adhesion of a coating to the surface, its mechanical durability and its resistance to environmental effects. Because a coating is a thin layer, the results depend both on the material and on the QUALITY OF APPLICATION; the same paint gives an entirely different result over a different surface preparation.
This dual dependence is the most important knowledge in the field. A coating failure usually arises not from the paint itself but from the surface preparation: oil residue, insufficient roughening, an oxide layer or moisture. Coating tests therefore assess not only the product but also the process, and the results are used for process control.
COATING THICKNESS is a recurring variable in the field. Many durability results relate directly to thickness; a thin area becomes the starting point of corrosion. Thickness measurement is therefore reported routinely alongside the other tests and is usually taken at several points — thickness falls at edges and corners, especially on complex geometries.
Three approaches are used on the adhesion side, each giving different information. The tape test is fast and suitable for field use but is a coarse scale. The cross-cut test shows behaviour at the intersections of layers. The pull-off method produces a numerical strength value and is the most suitable for comparison.
On the mechanical side, flexibility (mandrel bending), impact resistance, hardness, abrasion and stone chip resistance are measured. Stone chipping has a special place in automotive: gravel striking the coating under real road conditions is simulated, and the result is assessed according to whether the coating continues to protect the base metal.
On the appearance side, gloss and colour difference are monitored NUMERICALLY. Colour is assessed with a colour measuring instrument rather than by eye and the colour difference is expressed as a number; this makes it possible to compare different lots and different suppliers.
On the durability side, accelerated ageing (xenon arc, fluorescent UV), humidity, condensation and salt spray are applied. The result is assessed with scales for blistering, rusting, creep from a scribe and loss of adhesion; these scales are defined in separate standards and the report must state which was used.
In industrial processes such as powder coating and electrophoretic coating, the curing cycle (temperature and time) is what determines the result. An under-cured coating looks good but has poor chemical resistance and adhesion; oven profile measurement is therefore part of coating quality control.
Method groups in this field
Thickness
Dry film thickness by magnetic and non-magnetic methods; multi-point measurement and assessment of the distribution.
Adhesion
Tape test, cross-cut test and pull-off adhesion strength.
Mechanical strength
Mandrel bend flexibility, rapid deformation (impact), pencil and scratch hardness, Taber abrasion, stone chipping.
Appearance
Gloss measurement, colour difference calculation, orange peel and surface defect assessment.
Environmental durability
Salt spray, humidity, condensation, xenon arc and fluorescent UV ageing, chemical and stain resistance.
Assessment scales
Scales for blistering, degree of rusting, creep from a scribe and loss of adhesion.
Commonly confused in this field
- A coating result depends on the surface preparation; even if the paint itself is good, a poor preparation gives a poor result.
- A durability result without a reported thickness cannot be compared.
- The tape test is a coarse scale; numerical comparison requires the pull-off method.
- Colour cannot be assessed by eye; numerical colour difference measurement is required.
- An ageing result without a stated assessment scale cannot be interpreted.
- If the curing cycle is incomplete the coating looks good but its durability is poor; the oven profile is part of quality control.
Which decisions these results support
- Paint system approval and supplier selection
- Process control of the paint line and lot acceptance
- Supporting outdoor and automotive durability claims
- Detecting defects arising from surface preparation
- Monitoring colour and gloss consistency lot by lot
Related Tests
Frequently Asked Questions About UV
How many years of outdoor exposure does 1000 hours of UV correspond to?
Such a cycle cannot be made. Time-lapse UV testing is used to compare materials and capture formulation changes; cannot be converted to natural exposure time.