ASTM D1735 Standard Practice for Testing Water Resistance of Coatings Using Water Fog Apparatus

    ASTM D1735 Introduction

    ASTM D1735 can be used to reproducibly measure the quality of coatings in resisting water penetration in condensing, humid environments. Exposure to water is likely to degrade, discolor, and even fail the protective performance of coatings. Although the fog apparatus used in this method is similar to that applied in salt spray testing (ASTM B117), it does not induce ionic corrosion by using demineralized water; therefore, it is particularly suited for environments where pure water condensation is the primary factor. 

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    Get Certified ASTM D1735 for Coating Water Resistance Performance

    ASTM D1735 certification guarantees that the resistance to water of the coating is assessed under a standardized environment using a controlled water fog. Compliance ensures that the coatings can withstand long durations of exposure to moisture without any considerable deterioration, blistering, or loss of adhesion. Published by ASTM International, the practice is common to quality control, research, and durability performance of protective coatings.

    Scope of ASTM D1735

    • Coating subjected to continuous exposure to water mist.
    • Relates to paints, coating systems of protection, and varnishes.
    • Stipulates apparatus requirements such as temperature and fog production.

    ASTM D1735 Equipment and Sample Preparation

    Specimen DetailsCoated panels or prepared substrates are the real-world conditions of use; they are usually steel, aluminum, or wood.
    Specimen PreparationIf desired, the substrate must be washed and pre-elaborated with surfaces to suit the requirements of the producer of the film to be produced, and its treatment.
    Specimen DimensionsThe usual size of a specimen is 75 mm x 150 mm (3 x 6 inches) or other sizes that fit within the chamber rack, with thickness depending on the substrate content.

    Applications of ASTM D1735

    • Protection testing of industrial protective finishes.
    • Durability of automotive and marine coating analysis.
    • Architectural and structural paint controls.
    • Development of moisture-resistant coating.

    ASTM D1735 Common Challenges and Troubleshooting

    These problems are behavioral, intermittent dispersion of the water droplets, inefficient temperature control, and unnatural preparation of specimens, which may result in malpractice. The nozzles are to be washed properly, and the seals are to be kept properly in the chambers, as well as the temperature and humidity sensors must be calibrated so that the testing becomes repeatable and precise.

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    ASTM D1735 Aggregate Testing Technique, Process, and Data Collection

    ASTM D1735 involves the use of coated test panels in a water fog chamber, whereby atomized water is constantly produced under controlled temperature. The fog is applied on the surfaces of the specimens, which mimics the conditions of high-humidity or wet services. The length of exposure is set predetermined time depending on the requirements of the product. Following exposure, inspection and evaluation of panels visually is done to determine blistering, discoloration, rusting, softening, or adhesion loss.

    ASTM D1735 Testing Procedure and Requirements

    PrincipleCoated specimens are placed within a continuous, indirectly fogged chamber of demineralized water, and water is allowed to free-set on all open surfaces.
    Scope of MeasurementDetermines the water resistance when in fog conditions; no details on how the sample will be prepared, the test duration, or the criteria of post-test evaluation.
    AssumptionsCoating is done in a manner that allows the deposition of the mist to indicate the possible weaknesses. There is no corrosion interference from salt.

    ASTM D1735 Analysis Results and Interpretation

    Findings show that the coating can withstand the penetration of moisture and degradation. Little blistering, corrosion, or loss of adhesion, good water resistance, and protective performance. Significant defects indicate that formulations are weak, the surface is not prepared well, and the film is not thick enough. It can be compared with internal specifications or historical data to understand the suitability of products to be used in humid or wet service environments.

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    ASTM D1735 Problem & Solution

    When in contact with moisture, coating exposures can also fail early, blister, corrode, or lose adhesion, leading to structural damage and maintenance expenses. ASTM D1735 is a controlled water fog test that can be used to replicate wet environments and test adhesion stability in coating/paint to be sure that it will withstand the presence of moisture before it is used in the field.

    Updated on September 17, 2026

    Davis Scott
    About Author
    Davis Scott
    Davis Scott is an Electrical and Electronics Engineer specializing in multidisciplinary validation, quality assurance, and comprehensive electro-mechanical testing.
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