Mold in Wood Products:

FungiType– Molds– Sapstains– Decay

Damage– Stain surface– Stain Surface

and interior– Destroy wood,

may stain

PENICILLIUM

TRICHODERMA

STACHYBOTRYS

Important GeneraStachybotrysFusariumPenicilliumAspergillusChaetomiumTrichoderma

Mold ID

Kits easy to distributeThere is money in it, but..Sample collection importantDoes species matter if moisture is the problem?

Mold Species

250 to 300,000 species45 species on Douglas-fir sapwood lumber in the first 6 weeks

Risks of Mold and Stain

Increase wood permeabilityReduce surface appearanceReduce toughnessHealth effects (spores/ volatiles/contact)

Effects of Molds

Allergens (most)Human pathogens (few)Mycotoxins (few)

Mold Risk Factors

Fungal speciesMoistureSpore loadIndividual sensitivity

STACHYBOTRYS

Factors Affecting Fungal Growth

Sapwood ContentTemperatureWood Moisture ContentTime of YearTreatments

Mold Prevention

Short log storageSprinklingKiln dry within 48 hrs. of sawingKeep wood dryChemical treatments

Anti Stain/Mold ChemicalsNP-1: 3-iodo-2-propynyl butyl carbamate(IPBC) plus didecyl dimethyl ammonium chloride (DDAC)Britewood XL: Propiconazole plus DDACMycostat P: PropiconazoleNex-Gen: Methylene bisthiocyanate plus tetrachloroisophthalonitrile

Chemicals (Cont).

PQ-8: Copper-8-quinolinolateTuff-Brite: TetrachloroisopthalonitrileSta-Brite P: IPBCBritewood XL: orthophenylphenate

Performance of AntisapstainChemicals

0

20

40

60

80

100

120

30 90 180

Days After Treatment

Deg

ree

of D

isco

lora

tion

(%)

PropiChloroCu-8IPBC/DDACControl

Treatment of KD LumberPropiconazolePropi/DDACDDAC/IPBC

Post KD Treatment Effectiveness

01020304050607080

Deg

ree

of D

isco

lora

tion

(%)

1 mo DF 6 mo DF 1 mo HF 6 mo HFTime Since treatment (months)

PropiPropi/DDACDDAC/IPBCNone

KD TreatmentProvides short term protection against rewettingProtection declines w/storage timeHigher conc. may be useful

Color Removal1-3 % hydrogen peroxide0.3 % NaOH4 % Na-silicate(Lee, 1994)

Peroxide Effect on Brightness

02468

1012141618

30 60 90

Exposure Time (min)

Whi

tene

ss Im

prov

emen

t (%

)

50 C60 C70 C

Peroxide BleachingCostlyEffect shallowDoes not kill fungus in wood

Mold Removal

Power washBleachBiocides

Mold/Stain Removal

Heavily stained Douglas-fir sapwoodBoards washed with 0-20 % bleachSelected boards treated with TimborBoraCare, or DDACIncubated for 4 weeks at 32 CFungal colonization determined

Ability of bleach to reduce fungal discoloration

-70

-60

-50

-40

-30

-20

-10

0No wash 0 2.5% 5% 10% 7.5% 15% 20%

Bleach concentration

Cha

nge

in p

erce

nt o

f sur

face

con

vere

d by

fung

i

Mold Sapstain

Ability of bleach to reduce fungal isolations

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

No wash 0 2.5% 5% 10% 7.5% 15% 20%

Bleach treatments

Isol

atio

n fr

eque

ncy

Trichoderma Penecillium Graphium Zygomycotina

Effect of anti-fungal compounds on wood appearance

-30

-20

-10

0

10

20

30

control water 10% bleach

Cha

nge

in p

erce

nt o

f sur

face

con

vere

d by

fung

Control Boracare Timbor DDAC

Ability of boron to prevent Graphium

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

control w ater 10% bleach

Pretreatment

Isol

atio

n fr

eque

ncy

control Boracare Timbor DDAC

Ability of boron to limit Trichoderma

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

control w ater 10% bleach

Pretreatment

Isol

atio

n fr

eque

ncy

control Boracare Timbor DDAC

Controlling Mold

Bleach reduces visual effectChemicals do not eliminate fungiMoisture control is essential

Future of Mold ProblemsLitigation moves through courts (>$2.4 Billion in 2002)Most litigation will fail, but….Homeowners will demand mold free materialsIndustry must respond to meet demand

Meeting the DemandImproved design to remove moisture from structuresDevelopment of more breathable materialsBiocide incorporation in materialsMoisture resistant materials