Guide 02 Quality assurance and type approval
What do damp heat, mould growth and salt fog tests simulate?
Damp heat, mould growth and salt fog tests each reproduce a different way that humid, tropical, coastal air damages equipment: moisture working into materials, fungus growing on them, and salt accelerating corrosion. All three sit inside JSS 55555 and are standard entries in a naval qualification schedule.
- Topic
- Quality assurance and type approval
- Checked
- 23 September 2026
- Sources
- 5
- Questions
- 5
01
Damp heat: steady state versus cyclic
Steady-state damp heat holds a specimen at a constant high temperature and humidity, for example 40 degrees Celsius and at least 93 percent relative humidity for 16 hours in one published qualification schedule, and mainly tests how much moisture the equipment's materials absorb. Cyclic damp heat instead swings the temperature up and down, for example between ambient and around 55 degrees Celsius at high humidity, so that condensation forms as the item cools and breathing draws moist air into enclosures as it warms.
The two are not interchangeable substitutes for each other. A design that copes with constant humidity can still fail a cyclic test if condensation reaches an internal component that the steady-state version never wetted.
02
Mould growth: does the equipment feed fungus
A mould growth, or fungus, test checks whether the materials used in equipment support fungal growth, and whether any growth that does occur affects how the equipment functions. Specimens are inoculated with specified fungi and kept warm and humid, typically for 28 days and extendable to 84 where growth is inconclusive. A published qualification schedule records this test at 30 degrees Celsius and above 90 percent relative humidity for 28 days.
India's IS 9000 Part 10 mould growth test has been superseded by IS/IEC 60068-2-10:2018, so a current specification is more likely to cite the newer standard even where older documents still reference IS 9000.
03
Salt fog: corrosion resistance, not a lifespan prediction
A salt fog, or salt spray, test exposes a specimen in a closed chamber to an atomised, neutral, about 5 percent sodium chloride solution at pH 6.5 to 7.2, held around 35 degrees Celsius for a set duration. IEC 60068-2-11 Test Ka and ASTM B117 both use essentially this method, and the DGQA laboratory at CQAE (WE), Bangalore, runs its salt corrosion chamber at the same 35 degrees Celsius.
A salt fog test compares how different materials, finishes or coatings resist corrosion under one standard accelerated condition. It does not directly predict how long a part will last in actual coastal service, because real exposure includes cycles of wetting, drying, temperature change and mechanical wear that the chamber does not reproduce.
What each test is checking
- Steady-state damp heat
- Moisture absorption under constant high humidity
- Cyclic damp heat
- Condensation and breathing as temperature swings
- Mould growth
- Whether materials feed fungus, and whether growth affects function
- Salt fog
- Comparative corrosion resistance under accelerated salt exposure
04
Reading these results together
None of these three tests stands in for the others, and a specification that names one is not satisfied by a report on a different one. A coastal or shipboard application typically requires evidence against all three, because a coating that resists salt fog is not thereby proven against mould, and a housing that keeps out condensation under steady-state damp heat may still let it in under a cyclic profile.
Asked next
Questions people also ask
What do damp heat, mould growth and salt fog tests simulate?
What is the difference between steady-state and cyclic damp heat testing?
Steady-state damp heat holds temperature and humidity constant, commonly around 40 degrees Celsius and above 93 percent relative humidity for 16 hours, to test moisture absorption. Cyclic damp heat swings the temperature between ambient and a higher point at high humidity, causing condensation to form as the specimen cools, which tests a different failure mode.
How long does a mould growth test take?
A typical mould growth test runs about 28 days at warm, humid conditions, for example 30 degrees Celsius and above 90 percent relative humidity in one published qualification schedule, and can be extended to 84 days where the result at 28 days is inconclusive. Specimens are inoculated with specified fungi rather than left to pick up mould naturally.
What conditions does a salt fog test use?
A salt fog test atomises a neutral, about 5 percent sodium chloride solution at pH 6.5 to 7.2 inside a closed chamber, typically held around 35 degrees Celsius, for a set duration. IEC 60068-2-11 Test Ka and ASTM B117 both use essentially this method, and it is the method the DGQA laboratory at CQAE (WE), Bangalore, runs its own salt chamber to.
Does passing a salt fog test mean a part will not corrode at sea?
No. A salt fog test compares corrosion resistance between materials, finishes or coatings under one accelerated condition; it does not directly predict service life, because it does not reproduce the wetting and drying cycles, temperature swings and mechanical wear that real coastal exposure involves. It is a comparison tool, not a lifespan guarantee.
Is IS 9000 still the standard for mould growth testing in India?
IS 9000 Part 10 has been superseded by IS/IEC 60068-2-10:2018, so a current specification is more likely to reference the newer standard. Older drawings and quality assurance plans may still cite IS 9000 by habit, which is worth flagging with the buyer rather than assuming the two documents test the same way.
Checked against
Sources
- 01Guidelines for Environmental Testing at CQAE (WE), Bangalore, Directorate General of Quality Assurance
- 02Salt Spray, Salt Mist and Salt Fog Test Standards, Ascott Analytical Equipment
- 03ASTM B117 Salt Spray Test Procedure, Infinita Lab
- 04IS 9000, Part 10, Mould Growth Test (1979), Bureau of Indian Standards, via Internet Archive
- 05Bureau of Indian Standards, Bureau of Indian Standards
This guide explains how the system works in general, as the documents above describe it, and was last checked on 23 September 2026. Rules and thresholds change: the governing document is the authority, not this page.
On this site
Where this meets the work
- The qualification schedule behind a DQA(N) type approval
- The DQA(N) type approved battery charging rectifier
- The marine engineering division
- Work carried out from the Visakhapatnam coast
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