Test method
ASTM G29 algal resistance testing
ASTM G29 determines the algal resistance of plastic films. Specimens are inoculated with an algal culture and incubated under light and humidity that favour growth, then examined for the growth that develops on the film.
- Result
- A rating or observationAs the standard defines it, against the untreated control
- Organisms
- An algal cultureFungi and bacteria need separate methods
- Asked for by
- Buyers of outdoor filmBuyers of indoor products rarely do
- Often paired with
- ASTM G21For fungal resistance outdoors
- Turnaround
- 14–30 daysDate confirmed before you ship
The test in four steps
Drawn as a schematic, not photographed at our bench. The drawings show the sequence; the conditions are the standard's.
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Treated film, control if possible
The treated film and, where possible, the same film untreated as a control.
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Inoculate with algae
The specimens are inoculated with an algal culture.
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Incubate under light
They are incubated under light and humidity that favour growth.
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Examine for growth
The film is examined for the growth that develops on it.
Solid green outline: treated. Dashed gray outline: untreated control. Green dots: the organisms.
What the test involves
It is the outdoor-exposure question: greenhouse film, agricultural film, cladding, signage, anything that spends its life warm, wet and lit. In an Indonesian climate that is most of the year, which is why buyers of outdoor film ask for it and buyers of indoor products rarely do.
Algae, fungi and bacteria are three separate problems with three separate methods. A product exposed to all three needs more than one test, and we would rather say so before you book than after.
We run ASTM G29 in our BSL-2 laboratory in Bandung, certified annually by the International Antimicrobial Council (USA) and participating in AATCC's PTP4 antibacterial proficiency program.
What you receive
- An independent test report in IAC or AATCC format
- The rating or observation the standard defines, against the untreated control
- A certificate your customers, auditors, and procurement teams can verify
Common questions
My film is going outdoors. Do I need ASTM G21 as well?
Often, yes. ASTM G21 covers fungal resistance and ASTM G29 covers algal resistance; an outdoor film in a tropical climate is exposed to both. Tell us the application and we'll advise which of the two your buyer's specification actually requires.
Is this test only for films?
The standard is written for plastic films. If your product is a moulded or rigid article, send us the material and the exposure and we'll confirm whether this method applies or whether another one fits better.
What samples do I send?
The treated film and, where possible, the same film untreated as a control. We'll confirm sizes and quantities when you book.
How long does it take?
14–30 days, depending on the method and the current queue in the lab. We confirm the date when we accept the sample, before you ship anything.
Related methods
Not sure which one your buyer wants? Send us the specification and we will read it with you before any sample ships.
Book an ASTM G29 test
Tell us what the film is and where it will be used. We'll confirm the method and what the report will contain.