FUNGI, BUT NOT A FUN GUYWhich textiles are most

resistant and susceptible to mould growth?

BY MIKAYLA CHECK

ABSTRACTI chose to execute this investigation with Alicia as my house is of high humidity due to its

location by a wet sclerophyll rainforest, and consequently is vulnerable to mould. So often I awake to discover mould on my windowsill, blinds, clothes, sheets and pillows, but some pillows

have more (visible) mould growing on them than others; so I am left to wonder why mould is attracted to some pillows more than others when they are the same thickness and density.

I concluded that it was possibly that mould was attracted to some fabrics more than others, and, after not being able to find any research on the topic, decided that I would establish the facts

once and for all, to help not just my family, but all those families living in dense climates who are sick of allergies, cleaning mould, and its constant reappearances, despite the fact that mould

‘removal’ substances are used.

INTRODUCTIONIt’s cold and damp in your home. All you want to do is lay down in your warm, cosy bed; but

alas! What are those black dots on your pillow and sheets?It’s a bitter morning. You reach out to draw your curtain to allow some light and warmth in your

room; but wait a minute… why are your curtains suddenly covered in stains? And what is that repulsive odour?

You go to your dresser to get ready for the day. You pick out your favourite red t-shirt, blue shorts and black boots, but quickly put them back after realising that they are covered in white

spots. You choose a new outfit and find the same white spots, and it isn’t long before you realise that your entire wardrobe – and most of the textiles in your house for that matter – is covered in

MOULD.For so many people, mould is a constant issue in the home due to the humidity in the air (55%

or more humid is the environment in which mould thrives most). Unfortunately, in most cases it is unable to be treated as the remedies simply kill the mould and give it potential to grow back, therefore prevention and limiting its growth are critical measures which must be taken. Whilst

some air conditioners and dehumidifiers help in reducing the growth of mould, it is still a recurring issue, and these machines are not eco-friendly nor financially friendly!

This experiment, which will determine the textiles most resistant and susceptible to mould, will encourage substitutes in the fabrics selected when choosing clothing and homewares to

minimise mould growth and its endless effects on humans and the things that it grows on (gradually, everything which mould grows on will be destroyed).

Although mould is essential to the decomposition of dead organic matter, mould spores which are brought or grown indoors due to moisture in the home can pose major health risks and even fatalities. Exposure to mould has been proven to cause asthma and respiratory conditions, sinus complications, migraines and headaches, fatigue, itchy, watery and red eyes, dermatitis, chronic cough, and an inconclusive study discovered that the mycotoxins produced by toxic moulds may

cause neurological impediments and possibly fatalities.If we can reduce the growth of mould within the home, the mould spores cannot reproduce as rapidly indoors, therefore meaning that less people and objects will be affected. Because the fungi is most likely to grow on textiles, the incorporation of more mould-resistant textiles will

ensure that other objects in the home are not affected as badly by mould as the spores may be less attracted to the home itself.

In this experiment, I am not only testing different textiles and their susceptibility to mould growth, however also the texture of the fabrics by testing both knitted wool and wool felt, and

standard cotton and waffle weave cotton, to ensure that the experiment provides an almost certain indication as to which textiles are most and least resistant to mould, or at least provide a

clue as to why the mould grows better on some fabrics as opposed to others.

AIMThe aim of this experiment is to determine which textiles are the most and least mould resistant in an environment which mould thrives best in, therefore determining which textiles should be

limited in their use in damp, cold homes and environments in order to counteract medical concerns and the deterioration of furniture.

HYPOTHESISThe outcome of this experiment will reveal that each type of material has a different susceptibility and

resistance to mould. In order, the most to least amount of mould growth on the material will be:• Standard Cotton (due to the mass growth on Mikayla’s pillows and bedsheets)

• Waffle Weave Cotton• Polyester

• Chunky Knit Natural Wool• Rayon

• Cotton (Denim)• Wool felt (as in its creation it is already exposed to density and humidity, therefore its susceptibility to

mould growth may be less as it did not grow mould easily in the suitable conditions)• Nylon (elastomeric)

• Lycra (as its use in swimwear means that it is probably suited to dense conditions)

VARIABLESThe independent variable in this experiment is the textile placed in each snap lock bag.

The dependent variable in this experiment is the amount of mould which grows on each textile (and therefore the amount of mould spores which enter the bag whilst open) over this period of

time.The controlled variables are the amount of water placed into the bag, the size of the textile, the size of the snap lock bag, the strength of the seal on the snap lock bag, the temperature of the

water placed into the snap lock bag, the temperature of each snap lock bag (with the textile inside of it), the amount of light which reaches each snap lock bag (with the textile inside of it),

and the amount of air inside each snap lock bag.

RISK ASSESSMENT

There are numerous risks which must be taken into consideration for the duration of this experiment. I must be careful not to come into direct contact with the mould as it may cause

dermatitis, asthma or other conditions, therefore I will be wearing gloves to protect myself from these risks. However, I may also contract these diseases through inhalation; but inhaling the mould spores is inevitable in this experiment, so I will ensure that Ventolin puffers and other

pharmaceutical medicines are on hand in the event of asthma attacks or other dangerous reactions. I must additionally ensure that the mould does not grow on other furniture near the

experiment site, so I will consistently ensure that the nearby furniture is dry by towelling the pieces down each day.

MEASUREMENTSI will measure the growth of the mould by carefully analysing the textiles and comparing the textiles against one another to determine the most and least susceptible to mould growth.

REQUIREMENTSFor this experiment you will require the following:• A 10 x 10cm square of waffle weave cotton

• A 10 x 10cm square of chunky knit natural wool• A 10 x 10cm square of wool felt

• A 10 x 10cm square of nylon (elastomeric)• A 10 x 10cm square of rayon

• A 10 x 10cm square of standard cotton• A 10 x 10cm square of polyester• A 10 x 10cm square of Lycra

• A 10 x 10cm square of cotton (denim)• 9 snap lock sandwich bags

• 2 ¼ teaspoons of water (¼ of a teaspoon per bag)

DIAGRAM

TEXTILE

WATER

SNAP LOCK BAG

METHOD1. Place one square of fabric in a snap lock sandwich bag and add ¼ of a teaspoon of water

(1.23223 mL). Leave the bag open.2. Repeat step one until all bags contain water and a textile.

3. Place the bags in a dense, humid environment where mould has grown previously, such as a windowsill. Leave untouched for seven days.

4. After seven days, seal the bags and place in a dark, warm environment, such as a kitchen cupboard near an oven, stove or other commonly active heat source. Leave untouched for

seven days.5. After seven days, remove the textiles from the bags. Ensure that you are wearing gloves to

prevent possible health issues. Examine the amount of mould on the textiles to determine the results.

6. Rank the textiles from most to least resistant to mould growth based on the amount of mould on them.

RESULTSIn order from most to least susceptible to mould growth over this period of time, the textiles

were as follows:• Chunky knit natural wool

• Standard cotton• Rayon• Polyester

• Lycra, cotton (denim), nylon (elastomeric) , waffle weave cotton, wool felt

Name of Textile: Observations: Rank of Susceptibility (1 is most susceptible):

Chunky Knit Natural Wool Prominent black mould growth on edges.

1

Standard Cotton Slight mould growth near centre of textile. Most odorous textile.

2

Rayon Slightly odorous and faint mould growth.

3

Polyester Very faint mould growth with the appearance of stains.

4

Lycra NO MOULD GROWTH 5

Cotton (denim) NO MOULD GROWTH 5

Nylon (elastomeric) NO MOULD GROWTH 5

Name of Textile: Observations: Rank of Susceptibility (1 is most susceptible):

Waffle Weave Cotton NO MOULD GROWTH 5

Wool Felt NO MOULD GROWTH 5

Nylon (E

lasto

meric)

Knitted W

ool

Cotton (Denim

)

Waffl

e Weav

e CottonRay

on

Wool F

elt

Polyeste

rLy

cra

Standard

Cotton

Susceptibility to Mould

109876543210

RATE

/ 1

0 (1

0 IS

MO

ST S

USC

EPTI

BLE)

TYPES OF TEXTILES

The graph demonstrates the results as discussed previously, and the textiles which have been ranked as ‘0’ did not grow mould and therefore could not be rated on a scale of 1-10.

Mikayla’s Standard Cotton Pillows

POLYESTER LYCRA COTTON (DENIM)

NYLON (ELASTOMERIC) WOOL FELT WAFFLE WEAVE

CHUNKY KNIT NATURAL WOOL RAYON STANDARD COTTON

DISCUSSIONI encountered many difficulties during the duration of this project as I had to find a method

which ensured that the textiles would be in an environment of consistent and equal humidity. I originally followed the direction of my science teacher, Mr Evans, who advised to add 1 - 2 mL of

water to each snap lock bag and leave the bags in a warm, sunny environment in which the water could evaporate inside of the bag, therefore creating equally humid environments.

However, after some research, I discovered that mould requires darkness to grow, so I instead left the bags in a warm cupboard in our kitchen above our stove and oven. I then left the textiles

untouched for 7 days, however the mould was not growing on them, despite the fact that it generally takes approximately 48-72 hours for the mould to commence its growth. I then

remembered an article which I had read prior to beginning the experiment, which stated that mould requires the mould spores floating in the air to land on a wet surface in a humid,

generally dark environment in order for the mould to grow. Coming to the realisation that the snap lock bags which the textiles were inside of were sealed, I was able to fathom that the

mould spores could not land on the textiles through the bags. Therefore, I decided to restart the experiment, this time placing the textiles inside of the snap lock bags with ¼ of a teaspoon of

water in each, and leaving the bags open to allow the mould spores access to the textiles. I progressed to place the bags in an environment obviously suitable for mouth growth, as

demonstrated over many years of mould growth on my pillows, windows, furniture, blinds and carpet. This environment was on the windowsill in my bedroom. Whilst the textiles were not in

complete darkness for the duration of the experiment, they endured the same conditions, therefore making the experiment a fair test. I noticed that the mould began to grow on some

textiles after just 2 days, confirming that my mid-experiment hypothesis about the access of the textiles for the mould spores was most likely correct.

Exactly one week after the re-commencement of my experiment, I became anxious when I discovered that there was not a lot of mould growing on the textiles, or at least not enough to

decipher exact ranks from most and least susceptible to the mould growth. Desperately researching methods to grow mould quickly whilst ensuring a fair test, I stumbled across a

method used to grow mould on bread, which stated that the bag in which the contents were in must be left open for at least half an hour to allow the mould spores access to the contents. The

bag must then be sealed to trap the mould spores in the bag.I realised that this was where the faults in my experiment lay; in the first experiment, I had

trapped the mould spores outside of the bag, and in the second experiment I had allowed the mould spores to exit the bags.

Being pushed for time, I decided to continue the second experiment by trapping the mould spores inside the bags after the textiles had been in open bags for a week. Because the mould

spores were trapped inside of the bag, it essentially didn’t matter where I placed the bags to sit for an additional week. I hastily chose to place the textiles in their original location; the

cupboard above the oven and stove.My hypothesis for this experiment was incorrect; I predicted that the standard cotton would be the most susceptible to mould due to the significant amount (as opposed to other materials) of mould which grows on my pillowcases which are composed of the same materials. However, the

chunky knit natural wool was the most susceptible to mould growth over this period of time.

If I were to repeat this experiment, I would carry the experiment over a longer period of time. Additionally, I would carry out further investigations to determine why mould grows so rapidly on my standard cotton pillowcase, whilst it did not thrive as vividly in this experiment. I would

take the following elements into perspective;• Does pressure additionally affect the growth of mould (like my head rests on my pillow)?

• Does human contact in forms such as perspiration affect the growth of mould?• Were the conditions in the experiment not as humid as the environment created when the

heat from my head radiates onto my pillow?

I have no theory as to why the mould has grown better on the natural wool knit as opposed to the other textiles. Initially, I had thought that it was in relation to the origin and handling of the

textiles; the fact that some textiles were synthetic (i.e. Lycra), some were of plant origin (i.e. cotton) and some were of animal origin (i.e. wool). I thought that the textiles may not have grown mould due to the fact that they were exposed to large amounts of water during their manufacturing (such as the wool felt being pressed with water as part of its formation). In

retrospect, some textiles may have additionally been treated with chemicals to prevent mould, however this is highly unlikely.

However, this experiment has proven that the location or use of knitted natural wool (or possibly just natural wool in general) should be taken into special consideration, and should not be

placed in moist or humid areas. This textile is considerably popular in the average household; used for blankets, clothing, pillows, toys and accessories, therefore limiting its use would have a

significant impact on the attraction of mould spores within damp environments.

CONCLUSIONIn conclusion, whilst this experiment did not explicitly determine which textiles are most

resistant the mould growth (over this period of time), I discovered that the chunky knit natural wool was the most susceptible to the growth, and should therefore be limited in its use in

homes of high humidity to counteract health issues and deterioration of other furniture. I am still curious as to why my cotton pillow was highly susceptible to mould growth outside of this experiment, and therefore I will carry out further investigations (noted in my discussion) in the

near future.

ACKNOWLEDGMENTSWe would like to thank the following people for their contributions to this experiment:

• My mother, for allowing me to cut up old clothes and for purchasing the materials for the presentation of the board

• My science teacher, Mr Evans, for advising me as to how to execute this experiment and for allowing me to submit this project into the Shoalhaven Science Fair

• The judges of this experiment, for providing the foundation to this contest• Miss Mainey, for permitting me to work on my science fair board at home

BIBLIOGRAPHYhttp://blackmold.awardspace.com/prevent-mold.html (accessed 26/7/2015)

http://www.epa.gov/mold/moldguide.html (accessed 27/7/2015)http://www.public.health.wa.gov.au/cproot/2887/2/Mould+Fact+Sheet.pdf (accessed

31/7/2015)http://www.indiacurry.com/faqstore/coldesthottestplaceinhouse.htm (accessed

1/8/2015)