ISO 4611 Plastics Determination of the Effects of Exposure to Damp Heat Water Spray and Salt Mist

ISO 4611 is an internationally recognized standard that sets guidelines for assessing the effects of exposure to damp heat, water spray, and salt mist on plastics. This standard provides a structured approach to determining the durability and performance of plastic materials in different environments. Manufacturers often rely on ISO 4611 to ensure the quality and reliability of their products in real-world conditions. ISO 4611 is a standardized testing method used to evaluate how plastics perform when exposed to damp heat, water spray, and salt mist.

These tests are crucial in determining the resistance of plastics to corrosion and degradation, especially in harsh environmental conditions. In this article, we will explore the significance of ISO 4611 and its relevance to various corrosion testing methods, including salt mist testing, salt fog chambers, cyclic corrosion testing, and ASTM corrosion testing. ISO 4611 provides a comprehensive framework for evaluating the effects of exposure to damp heat, water spray, and salt mist on plastics.

Through salt mist testing, salt fog chambers, cyclic corrosion testing, and other methods, the industry can better understand the corrosion resistance and durability of plastic materials. Manufacturers can use these insights to enhance product quality, optimize material selection, and improve their products’ performance in various applications. By adhering to ISO 4611 and utilizing advanced testing techniques, companies can ensure their products meet the highest standards of reliability and longevity, even in challenging environments.

ISO 4611 Plastics Determination of the Effects of Exposure to Damp Heat Water Spray and Salt Mist
Type and Description WEW-YW-90D WEW-YW-120D WEW-YW-160D
Inner Dimension(mm) 900*600*500 1200*800*500 1600*1000*600
Outer Dimension(mm) 1410*880*1280 1700*1150*1200 2300*1250*1450
Test Room Size (Liters) 270 Liters 500 Liters 1000 Liters
Power Supply AC 220V, 50Hz AC 220V, 50Hz AC 380V, 50Hz
Power Current 1Phase, 2.0 kW 1Phase, 2.9 kW 3Phase, 5.0 kW
Lid Opening Method Manual Opening Manual Opening Air-Operated
Brine Tank Volume 25 Literes 30 Literes 40 Literes
Test Room Temp Range Ambient Temperature +5℃ – +30℃, Ventilation is recommended, if the temperature exceeds +30℃, it is recommended to adjust the room temperature by suitable means. Ambient humidity should be controlled below 80%RH.
Test Room Temp Range RT+10℃ – +55℃ RT+10℃ – +55℃ RT+10℃ – +55℃
Saturated Barrel  RT+10℃ – +70℃ (Purpose: Heating and filtering of compressed air to reduce nozzle crystallisation.)
Temp Performance Temperature Uniformity: ≤2℃,  Temperature Fluctuation: ≤ ±0.5°C Temperature Uniformity: ≤2℃, 
Salt Mist Settling Rate 1~2 ml/80 cm2/h (Take 16 Hours To Test The Average Value) 1~2 ml/80 cm2/h
Spray Method Continuous, Intermittent,  Programmable Tests Continuous, Intermittent, 
Safety Devices Over-Temperature Alarm (Mechanical Over-Temperature Protection + Electronic Over-Temperature Protection Double Over-Temperature Protection)
Air Requirements Two-Stage Pressure Regulation. Inlet Pressure Above 0.4Mp. Spray Pressure 0.07~0.17mp (Adjustable)
Sample Holder Special Samples Support Customisation. Special Samples Support Customisation. Load Capacity According To Actual Situation
Standard Configuration 1 Set Of V-Type/O-Type Shelves, 2 Bottles Of Test Drug Sodium Chloride (500g/Bottle), 1 Plastic Anti-Rust Bucket (5l Capacity), 1 Nozzle

The principle behind the testing process involves determining one or more properties both before and after specified periods of exposure in specific environmental conditions. During this exposure, any changes in appearance are carefully observed. In certain cases, further testing may be conducted after exposure, followed by a subsequent drying or reconditioning treatment. The objective of this treatment is to achieve the same state of equilibrium with atmospheric humidity as that of the initial specimens.

By adopting this methodology, a comprehensive understanding of the material’s performance under varying conditions can be obtained. Salt mist test chambers offer specialized facilities for conducting ISO 4611 compliant tests. These chambers are designed to create controlled environments, where test samples are exposed to salt mist, humidity variations, and temperature cycles. Salt mist test chambers ensure accurate and reliable test results, enabling manufacturers to assess the performance of plastics under harsh conditions.

salt spray testing
5.1.1 In this type of test, the changes in mass are at least partially due to water absorption, and they are therefore particularly influenced by the conditioning and drying/reconditioning of the test specimens. 5.1 General 5 Change of Mass
It is important, therefore, that the precise conditions of test be specified in the relevant product specifications.
Normally, the specimens are weighed immediately after exposure, rinsing and wiping dry, or are treated as described in
If the determination of mass after drying or reconditioning is required, the specimens shall be dried or reconditioned as specified in
Note This test is not applicable to cellular materials.
5.1.2 The changes of mass are generally proportional to the surface area of the test specimens, but are influenced by their thickness.
IMPORTANT — It is emphasized that the comparison of different plastics by means of this test is valid
only if the test specimens used are of the same shape, the same dimensions and in as nearly as possible the same state (of surface, internal stresses, etc.).
5.2.1 General 5.2 Test Specimens
The test specimens may be obtained directly by moulding or by machining. In the latter case, the cut surfaces shall be smooth and shall not show any trace of charring that may be due to the method of preparation.
5.2.2 Moulding and Extrusion Compounds
The test specimens shall be in the form of a square of (50 ± 1) mm side and (3,0 ± 0,2) mm thick. Rectangular specimens having the same surface area (for example 100 mm × 25 mm, i.e. 2 500 mm 2 ) may be used.
The specimens may be cut from a sheet of the same thickness, or prepared by compression or injection
moulding or by extrusion under the conditions given in the relevant specification for the material or under the conditions prescribed by the supplier of the material.
Moulding materials may be, alternatively, directly moulded in a mould of the prescribed dimensions.
Note The general principles for preparing moulded and machined test specimens are the subject of the following
International Standards: ISO 293, ISO 294-1, ISO 294-2, ISO 294-3, ISO 295, ISO 2818.
5.2.3 Sheet
The specimens shall be (50 ± 1) mm square or rectangular, having the same surface area, and shall be cut from the sheet under test.
If the nominal thickness of the sheet under test is equal to or less than 25 mm, the thickness of the test specimen shall be the same as that of the sheet.
If the nominal thickness is greater than 25 mm and in the absence of special provisions in the relevant specification, the thickness of the test specimen shall be reduced to 25 mm by machining on one surface only.
The machined surface shall not be directly exposed to water or salt spray.
A complete description of the machining, if any, shall be included in the test report.
5.2.4 Semi-finished and finished products (other than sheets)
The specimens shall be as similar in shape and size as possible to the specimens described in 5.2.2, and be prepared in accordance with the product specification or as agreed upon between the interested parties.
If any machining is necessary, a complete description thereof shall be included in the test report.
5.2.5 Number of Test Specimens
At least three specimens shall be tested.
See 4.3.1. 5.3 Conditioning
5.4.1 Determine the mass (m 1 ) of each specimen to the nearest 0,001 g. 5.4 Procedure
5.4.2 Expose the specimens to the test environment chosen from those listed in Clause 4.
5.4.3 Rinse, if necessary (for example in the case of exposure to salt mist), and wipe the specimens dry.
5.4.4 Immediately determine the mass (m 2 ) of each specimen to the nearest 0,001 g.
5.4.5 Dry or recondition the specimens, if required, in accordance with and determine the mass (m 3 ) of each specimen to the nearest 0,001 g.
5.5.1 The change of mass per unit area, in grams per square metre, is given by the formula 5.5 Expression of results
5.5.2 The change of mass, as a percentage, is given by the formula
The change is positive for increase of mass and negative for reduction of mass.
5.5.3 Calculate the mean value of the test results for all the specimens from a given sample.
salt spray fog apparatus
Equipment used for exposing specimens to steady state or cyclic exposure conditions involving heat, humidity, and water or salt spray shall be made from corrosion resistant materials that will not interact with or contaminate the specimens being exposed. In addition, the device shall provide a means to programme and time the various portions of the exposure cycles that are used. 4.1.1 General 4.1 Equipment Requirements 4 General Test Conditions
Sensing devices for measurement of temperature and relative humidity shall be located within the working volume of the chamber.
Any condensed water shall be continuously drained from the chamber and not re-used until re-purified.
No condensed water from the walls or roof of the chamber can fall on the test specimens.
Water used for the maintenance of the chamber humidity shall have a resistivity of at least 0,05 MΩ cm.
For the water spray (see 4.2.2) and salt mist (see 4.2.3) tests, the following additional equipment requirements shall be met. The cabinet shall have a volume of not less than 0,4 m 3 since, with smaller volumes, difficulties have been experienced in ensuring an even distribution of spray. For large-volume cabinets, it is nevertheless necessary to ensure that the spray is distributed homogeneously throughout the cabinet. The upper parts of the inside of the cabinet shall be designed so that any drops of spray which form on its surface cannot fall on the specimens being tested.
For the salt mist test (see 4.2.3), the apparatus should, for environmental reasons, preferably be fitted with equipment for treating the salt mist after the test, prior to releasing it to the atmosphere, and also with equipment for treating the salt water produced during the test, prior to discharging it to the sewage system.
For the water spray (see 4.2.2) and salt mist (see 4.2.3) tests, the device for spraying the water or salt solution shall include a supply of compressed air, a reservoir containing the water or salt solution to be sprayed, and one or more atomizers. Before it reaches the atomizers, the compressed air shall be passed through a filter to remove all traces of oil and solid matter, and the atomization shall be carried out at an overpressure of about 70 kPa. The level of the water or salt solution shall be maintained automatically. In order to prevent evaporation of water from the sprayed droplets, the compressed air shall be humidified, before entering the atomizer, by passing it through a saturation tower containing distilled or deionized water at a temperature 10 °C above that of the cabinet.
For the salt mist test (see 4.2.3), the characteristics of the mist produced will depend on the pressure used and on the type of atomizer nozzle. These shall be adjusted so that the concentration of the salt mist in the cabinet (as measured by the rate of deposition of the mist on a collection surface) and the salt concentration in the mist are kept within the limits specified in 4.2.3.
Note ISO 9142:2003, Annex E, describes exposure conditions similar to those used in this International Standard.
The exposure cabinet shall be capable of controlling the temperature in the exposure chamber to within ±2 °C of the desired equilibrium temperature. The temperature tolerance limits of ±2 °C are intended to allow for any systematic measurement errors, any temperature drift and any variations in temperature at different points in the chamber. However, in order to maintain the relative humidity throughout the chamber within the required tolerances, it is necessary to keep the temperature difference between any two points in the chamber at any given time within narrower limits. Specimens being exposed in the chamber shall not be subjected to radiant heat from the chamber temperature-control devices. 4.1.2 Temperature
The chamber temperature shall be measured at least 100 mm from the walls. General 4.2.1 Damp heat 4.2 Exposure Conditions
The preferred exposure conditions correspond to those described in the IEC publications referred to in and Different temperature and/or humidity conditions may be used, however, if specified in the relevant product specifications or by agreement between the interested parties. Steady state test
Unless otherwise specified, the chamber shall be at ambient laboratory temperature and humidity at the start of the test. Place the conditioned specimens (see 4.3.1) in the chamber and adjust the controls to produce the following conditions: temperature: °C;
As the chamber temperature is increasing to 40 °C, the rate of temperature change shall not exceed 1 °C/min, averaged over a period of not more than 5 min. During the heating-up period, condensation shall not occur on the specimens.
Once the specified temperature is reached, adjust the relative humidity to the specified level within no more than 2 h.
The period of exposure shall be as specified by the specification covering the material or product being tested.
When not specified, this period shall be agreed upon by the interested parties. Recommended periods of exposure are 12 h, 16 h, 24 h, 48 h, 96 h and 240 h.
Note The conditions given in this subclause correspond to those specified in IEC 60068-2-78:2001. Cyclic Test
This test takes the chamber and specimens through a number of 24 h cycles during which the temperature shall be maintained at an upper value and at (25 ± 3) °C. One of the following two temperatures shall be chosen as the upper temperature:
a) (40 ± 1) °C (in which case the number of cycles shall be 2, 6, 12, 21 or 56);
b) (55 ± 1) °C (in which case the number of cycles shall be 1, 2 or 6).
The upper temperature shall be reached within the first 3 h ± 30 min of each 24 h cycle. During this temperature increase, the relative humidity shall not drop below 95 %, except during the last 15 min when the relative humidity may drop below 95 % but not below 90 %. During the temperature increase, condensation on the specimens is allowed.
In the following hours, the temperature shall be maintained at the upper value chosen and the relative humidity shall be maintained at (93 ± 4) %.
After 12 h of the 24 h cycle, the temperature shall be allowed to decrease, within 3 h to 6 h, to the lower temperature of (25 ± 3) °C. During this temperature decrease, the relative humidity shall not drop below 80 %.
For the rest of the 24 h cycle, the temperature shall be maintained at (25 ± 3) °C and the relative humidity shall not be less than 95 %.
Note 1 The conditions given in this subclause correspond to those specified in IEC 60068-2-30:2005 (using variant 2 for the temperature decrease part of the cycle).
Note 2 For composite temperature/humidity cycles, with the addition of a number of excursions to sub-zero temperatures, guidance can be found in IEC 60068-2-38.
The main difference between this exposure condition and that for damp heat/steady state (see is the constant presence of the liquid phase, in the form of small water droplets. 4.2.2 Water spray
Suitable equipment for obtaining these conditions is substantially identical to that for the salt mist exposure (see 4.2.3) and is described in the relevant specifications.
Distilled or deionized water, having a pH between 6 and 7, shall be used instead of the salt solution.
The temperature in the test enclosure shall be (40 ± 2) °C.
Dissolve a sufficient mass of sodium chloride in distilled or deionized water with a conductivity not higher than 20 μS/cm at (25 ± 2) °C to produce a concentration of (50 ± 5) g/l. The specific-gravity range for a (50 ± 5) g/l solution is 1,029 to 1,036 at 25 °C. 4.2.3 Salt Mist
The sodium chloride shall contain less than 0,001 % by mass of copper and less than 0,001 % by mass of nickel, as determined by atomic absorption spectrophotometry or another analytical method of similar sensitivity. It shall not contain more than 0,1 % by mass of sodium iodide or more than 0,5 % by mass of total impurities, calculated with respect to the dry salt.
Adjust the pH of the salt solution so that the pH of the salt mist collected in the chamber (see below) is between 6,5 and 7,2 at (25 ± 2) °C. Check the pH by electrometric measurement or, for routine checks, using short-range pH paper which can be read in increments or 0,3 pH-units or less. Make any necessary correction by adding hydrochloric acid, sodium hydroxide or sodium bicarbonate solution prepared from analytical-grade reagents.
The temperature inside the cabinet shall be (35 ± 2) °C.
The chamber shall contain at least two devices for collecting salt mist. These devices shall include a horizontal surface of area 80 cm 2 on which mist will be deposited during the exposure. They shall be placed so that only mist, and not liquid falling from specimens or from parts of the cabinet, is collected. They shall be used to ensure that the following requirements are met:
– The average collection rate shall be 1 ml/h to 2 ml/h when measured over a period of at least 16 h;
– The pH of the mist collected shall be between 6,5 and 7,2 at (25 ± 2) °C (see above);
– The sodium chloride concentration in the mist collected shall be (50 ± 5) g/l.
Note 1 The conditions given in this subclause correspond to those specified in ISO 9227:2006 and IEC 60068-2-11:1981.
Note 2 In this test, the exposure temperature used is 35 °C, even though this temperature is not included among those recommended in ISO 3205, because it is specified in ISO 9227 and in the majority of existing national standards.
The period of exposure shall be as specified by the specification covering the material or product being tested.
When not specified, this period shall be agreed upon by the interested parties. Recommended periods of exposure are 2 h, 6 h, 24 h, 48 h, 96 h, 168 h, 240 h, 480 h, 720 h and 1 000 h.
Unless otherwise agreed by the interested parties, the test specimens shall be conditioned before testing for at least 86 h at (23 ± 2) °C and (50 ± 10) % RH. 4.3.1 Conditioning 4.3 Test Specimens (See 5.2, 6.2 and 7.2)
For certain materials which are known to approach rapidly, or on the contrary very slowly, the state of equilibrium of temperature and, above all, of humidity, shorter or longer conditioning periods may be specified in the particular specifications concerning them (see Annex A). General 4.3.2 Treatment After Exposure
The exposed specimens shall be tested either
a) directly after the exposure, or
b) after the exposure and subsequent drying or reconditioning.
The first procedure shall be used when it is required to know the state of the material while it still contains the amount of water it had absorbed by the end of the exposure. The second procedure shall be used when it is required to determine the changes in properties of the material as a result of the exposure only. In the case of reconditioning, the specimens shall be brought back, as far as possible, to the same state as the initial state before exposure with regard to equilibrium with atmospheric humidity (see 4.3.1). Test After Exposure Only
After rinsing with distilled or deionized water, if necessary, and wiping dry, the exposed specimens shall be brought to (23 ± 2) °C in a closed container; usually 4 h are sufficient for this purpose. Test After Exposure And Drying or Reconditioning
After rinsing and wiping dry, the specimens shall be dried or reconditioned to equilibrium with the same atmospheric conditions as before the exposure (see 4.3.1), taking due account of the procedures described in
A.3.1 and A.3.2 in Annex A. Unless otherwise specified in the relevant product standard or agreed upon between the interested parties, the specimens shall be dried in an oven at (50 ± 2) °C for 24 h and cooled to (23 ± 2) °C in a desiccator.
Specimens more than 200 µm thick will not be in humidity equilibrium after 24 h (see ISO 62). Therefore, a longer drying time is recommended for such specimens. If a longer drying time is used, it shall be agreed upon by all interested parties and stated in the test report.
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