--- type: "WebPage" title: "VICAT/HDT laboratory testing" description: "You would like to perform VICAT/HDT testing in the laboratory Master the thermal resistance of your polymers: VICAT and HDT tests While material performance is subjected to increasingly extreme conditions, precise knowledge of the thermal behavior of your plastics is..." resource: "https://filab.fr/en/our-services/our-expertise-services/thermal-analysis-laboratory/vicat-hdt-testing/" tags: ["EN", "pll_69b3dfe1e3dba"] timestamp: "2026-03-23T10:44:01Z" published: "2026-03-13T10:41:22Z" language: "en" author: "Laure Durieux" --- # VICAT/HDT laboratory testing ## You would like to perform VICAT/HDT testing in the laboratory ### Master the thermal resistance of your polymers: VICAT and HDT tests While material performance is subjected to increasingly extreme conditions, precise knowledge of the thermal behavior of your plastics is no longer an option, it's a necessity. Our laboratory services, specializing in [thermal analysis](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/laboratory-material-testing/laboratory-analysis-thermal-thermogravimetric/), support you in the [characterization of thermoplastics](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/laboratory-analysis-of-thermoplastic-polymers.md) according to the strictest international standards (**ISO 306, ISO 75, ASTM D1525, ASTM D648**). ### Why measure the softening point and deformation under load? The success of a product often depends on a single factor: its **stability**. Whether for [automotive](https://filab.fr/en/sectors-of-activity/laboratory-analysis-automobile.md) components under the hood or sterilizable [medical devices](https://filab.fr/en/sectors-of-activity/laboratory-analysis-medical-devices.md), you need to know exactly when your material loses its rigidity. VICAT Softening Point (VST) ## The Vicat test determines the temperature at which a standardized tip penetrates 1 mm into the surface of your sample. This is the key indicator for defining the upper limit of a material's usability without significant mechanical stress. Load Deflection Temperature (HDT) ## The HDT test measures a material's ability to withstand a bending stress (0.45 MPa or 1.80 MPa) while being heated. It is the reference measurement for predicting the actual mechanical performance of your parts under operational conditions. ### Our VICAT and HDT analysis services Validation of heat resistance (solar and motor) Suitability for hot filling of a [PET](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/laboratory-analysis-pet.md) bottle Optimizing cooling time Comparison of the softening point of [PP](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/polypropylene-pp-materials-analysis-laboratory.md) and recycled PP Materials certification for electrical engineering ## The FILAB laboratory supports you in your VICAT/HDT testing ### Our laboratory thermal analysis services From analysis to R&D, the FILAB laboratory offers multi-sector services that meet several types of thermal analysis requests, such as: [Training in the ATG technique](https://filab.fr/en/our-services/rd/laboratory-analytical-chemistry-training/atg-training-for-laboratories.md) [Thermomechanical tests on polymers](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/thermomechanical-tests-on-polymers-in-the-laboratory.md) [Thermal diffusivity measurement](https://filab.fr/en/our-services/our-expertise-services/characterization-magnetic-electrical-properties/thermal-diffusivity-measurement/) [Thermal dilatation measurement](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/laboratory-material-testing/laboratory-analysis-thermal-thermogravimetric/thermal-expansion-measurement/) [Thermal analysis on polymer materials](https://filab.fr/en/our-services/our-analysis-services/polymer-materials-analysis-laboratory/laboratory-analysis-thermal-degradation-polymers.md) [Thermal conductivity measurement](https://filab.fr/en/our-services/our-expertise-services/characterization-magnetic-electrical-properties/thermal-conductivity/) [Thermal effusivity measurement](https://filab.fr/en/our-services/our-expertise-services/characterization-magnetic-electrical-properties/measurement-thermal-effusivity/) ### Our technical resources for the thermal analysis of materials Several thermal analysis techniques exist that can highlight the physicochemical specificities of the material as a function of temperature: [### Thermogravimetric TGA technology, TGA coupled with FTIR infrared](https://filab.fr/en/our-technical-resources/tga-tga-ftir-and-tga-ms-analysis-at-filab-laboratory.md) [### Differential thermal DTA](https://filab.fr/en/our-technical-resources/differential-thermal-analysis-dta-in-the-laboratory.md) [### Differential scanning calorimetry DSC calorimeter technique - Differential Scanning Calorimetry](https://filab.fr/nos-moyens-techniques/laboratoire-analyses-dsc.md) [### Thermal desorption Thermal desorber TDU coupled to gas chromatography GCMS](https://filab.fr/en/our-technical-resources/gas-chromatography-analysis-lab-gc/thermodesorber-analysis-in-the-laboratory.md) [### GC-MS-coupled pyrolysis (Py-GCMS)](https://filab.fr/en/our-technical-resources/py-gc-ms-pyrolysis-gc-ms.md) [### TGA coupled with DSC](https://filab.fr/en/our-technical-resources/laboratory-analysis-dsc-calorimetric.md) ## Our FAQ What is the fundamental difference between the VICAT and the HDT test? Although both tests measure heat resistance, their purposes differ: - VICAT: Measures the surface softening temperature. It determines when the material becomes "soft." This indicates the polymer's intrinsic thermal limit. - HDT: Measures deformation under mechanical load. It determines when a part will "bend" under its own weight or under external stress. This is a technical design (engineering) parameter. Why is my HDT result so much lower than the melting point (Tm) of my plastic? This is perfectly normal. The melting point (measured by DSC) is the point at which the polymer crystals completely disappear. However, the material loses its mechanical strength well before melting. The HDT test is therefore much more representative of real-world conditions than the melting point test. Can we test filled materials (fiberglass, talc)? Yes, absolutely. This is precisely where the HDT test is most relevant. Mineral fillers or fibers significantly increase the HDT temperature (sometimes by more than 50°C), because they reinforce the rigidity of the plastic matrix even when it begins to soften. What types of materials can be analyzed (and which are excluded)? VICAT and HDT tests are designed for materials exhibiting a gradual solid-to-liquid transition phase. **Ideal materials:** - Amorphous thermoplastics (ABS, PC, PS, PMMA): The transition is very sharp, making measurements extremely precise. - Semi-crystalline thermoplastics (PE, PP, PA6, PBT): The test reveals the influence of the crystalline structure on mechanical strength. - Plastic matrix composites (PA66 GF30, talc-filled PP): Essential for validating the contribution of reinforcements. - Bioplastics and bio-based polymers (PLA, PHA): Crucial for verifying whether these new materials match the performance of petroleum-based plastics. **Materials under specific conditions**: - Elastomers and flexible plastics (TPE, TPU): These can only be tested if they have sufficient rigidity at room temperature (23°C). If the Vicat needle penetrates without heating, the test cannot be performed. - Thermosetting resins: The sample must be perfectly flat and must not outgas during heating. **Excluded materials:** - Metals, ceramics, and mineral glasses: Their softening points far exceed the capabilities of oil baths (max 300°C), and their physical behavior requires other types of high-temperature mechanical testing. How to get a quote from FILAB? To obtain a quote, you can contact our team via our contact form, by phone, or by email. Simply tell us your requirements (type of material, desired analysis, applicable standards, urgency, quantity of samples, etc.). We will then send you a personalized technical and pricing proposal within 24-48 hours. What is the typical duration of the analysis? Turnaround times vary depending on the nature of the analysis and the complexity of the expert assessment project. However, FILAB is committed to providing fast turnaround times tailored to your industrial constraints and urgent needs.