Mold & Mildew-Free
Linseed Oil Products
No other Linseed Oil Paint
or wood preservative is mildew-free and made without chemicals like
linseed oil in our paint has been extensively cleaned and purified
to remove all protein and other impurities. This is what makes Allback
purified organic linseed oil
Our raw linseed oil can be exposed to the air for years without
ever turning rancid. Because there is nothing mildew can feed off
in our Linseed Oil Paint products, conventional
paint failure issues are not a problem.
More About Mildew: Study of Mildew and Algae on Exterior
Siding and Other Details (This study was written by: The
Paint manufacturer Association of Sweden - Stockholm, Sweden)
Painted or repainted exterior wood and foundation surfaces can
sometimes become gray, black or green in color, specifically on
the north side as well as areas that are continuously exposed to
This study is to shed light on mildew spores and algae of various
kinds. Sometimes it can be hard to distinguish mildew and algae
from dirt in the environment. To some extent, mildew can be controlled
with chlorine which will bleach the mildew and algae but will not
alter the color of the dirt. The problem with various types of growth
have increased in the last few years. Mild winters have caused an
increase in mildew growth. For example, the warm fall of 2000 in
Northern Europe followed by a mild winter, has caused mildew to
appear on surfaces that would normally be unaffected under more
normal seasonable temperatures. We will in this study attempt to
explain why various mildew and algae growth can develop on exterior
facades, doors and windows as well as offer techniques to avoid
the conditions that make these unwanted blooms occur.
In very high humidity, wood material can be attacked by a mildew
that causes internal decay and destroys the wood from the inside.
We will not highlight these types of mildew spores in this study.
There are many types of fungi. A common type is the black fungi.
These types of fungi are clearly visible especially when growing
on light colored backgrounds. Although unattractive, leaving black
spots on the surface,this fungi does not destroy the wood. The dark
spots are what make mildew visible but the threads, or roots, that
branch out from these spots are colorless.
Blånadssvampar (Latin name Aureobasidium pullulans)
These types of mildew spores can be found on new unpainted wood.
It flourishes in the timber grain but does not affect the integrity
of the wood.
These organisms are not related to mildew. Algae, like all vegetation,
contain chloroform and are made up from carbon dioxide present in
the air. Algae are not dependent on the nutrition found in the woodgrain
and are not destructive. The green coating you often find at the
bottom edge of exterior siding consist of algae.
Criteria for Flourishing Mildew
For mildew and algae to flourish and develop, there must be the
perfect environment for the organism. First the spores must cause
an infection, then there must be nourishment, moisture and the perfect
The spores that spread mildew can travel in the air during most
of the year in various concentrations. This means an exterior surface
can always be attacked by various spores if the conditions are right.
Paint that cures slowly ( oil and alkyd paint) can become more susceptible
to mildew growth after the paint is applied. On smoother and harder
surfaces, the spores and algae will have a harder time attaching.
Spores can also lay dormant in new timber before it is installed
and then develop when the temperature and humidity become favorable.
The storage and treatment of the timber is of great importance,
because already infected timber runs a significantly higher risk
of developing mildew after it is painted or varnished.
The mildew takes nourishment from the substrate it grows on, from
various types of sugars in the wood or from organic material found
in paint and other materials. Organic material in dirt (pollen etc.)
that attaches itself on the surface supplies excellent food for
mildew spores and algae. Algae receives much of its nutrients from
the air. The combustion of fossil fuel as well as other airborne
pollutants can contribute to feeding algae and mildew.
An important source of sustenance for mildew in wood are different
types of sugars and other substances that exist naturally in the
wood. When timber is milled, the nutrients will migrate toward the
surface. The faster the timber is dried, the more porous the wood
becomes, forcing the nutrients to collect near the surface of the
timber creating a higher risk of future mildew attack. Heart timber
is less susceptible to mildew growth than the surface fibers in
the timber. If wood is left in the weather without protection mildew
will have a better chance to develop.
Moisture and Temperature
Mildew spores and algae need water to live and flourish. The more
moisture, the greater the mildew growth. A porous surface can absorb
significantly more moisture and therefore will become more susceptible
to mildew growth. Cracks where moisture and dirt can accumulate
can often become fertile ground for mildew growth that will spread.
(Dark surfaces exposed to the sun that dry quickly and becomes warm
and dry will rarely accumulate mildew.?)
Climate and the weather have an enormous effect on mildew and algae
growth. At approximately 40 degrees F. mildew and algae become active
and start reproducing and spreading. High temperatures, ideally
around 80 degrees, but not above 95 degrees F., together with high
humidity are extremely favorable conditions for growth.
Wet summers, a warm fall and a mild winter will significantly increase
the chance of mildew and algae.
Building Design and the Surrounding Areas
How a building is constructed and sited is very important in order
to keep water and moisture away from building material. A good drainage
system around your building is imperative. A sufficient overhang,
wide sofits and proper flashing are essential building elements
that will keep surfaces dry. Wood that is situated too close to
the ground or exposed to leaking gutters will always result in excessive
surface moisture and will result in increased mildew and algae growth.
Bushes, ivy and other types of vegetation close to a building will
also increase mildew and algae growth on exterior siding and foundations
because shading and lack of air flow retain dirt and moisture.
Paint and Varnishes
Timber that is painted or varnished will have less chance of mildew
and algae growth but will also come under attack if the conditions
In general, it is hard to determine what types of paint are more
susceptible to mildew and algae. Smooth and dense surfaces are less
prone to mildew and algae growth. Paints that create a textured
surface are more apt to have spores attaching, resulting in mildew
growth. But,if the surface is able to dry quickly because it is
exposed to the sun or is well ventilated, then there is less chance
of discoloration from mildew or algae growth.
Concrete, stucco , lime based paint and silica based paint tend
to have significantly less chance of mildew and algae growth, but
it does happen. A paint with an organic binder is somewhat more
sensitive. The surface preparation can reduce the mildew risk if
the surface is smooth and more water repelling.
Mildecide – Anti Mildew Chemicals
Paints for exterior use that are based on organic binders like linseed
oil, alkyd or latex, usually contain some substance that will prevent
growth on the surface. The addition of mildecides and fungicides
will initially prevent mildew and algae growth. But with time, these
will evaporate and leave the surface susceptible again.
Due to environmental reasons, new regulations have made many of
these chemical substances illegal to use. The timber milling industry
has also been forced to change many practices. This means that you
can not completely protect yourself from mildew under certain conditions.
It is often not a matter of any defect in the paint products when
a surface develops mold and mildew. Instead, it is a result of needed
compromises between environmental considerations and mildew resistance.
Suggestion when discovering mildew and algae growth:
- Evaluate to determine if any building construction or immediate
surroundings can be improved.
- Attempt to wash the surface with an environmentally safe soap.
Do not use a dry brush because spores can cause allergy symptoms.
Use gloves. Power washing should be avoided due to the great chance
of introducing large amounts of water into areas that have never
previously seen moisture.
- If washing is not solving the problem, stronger disinfection
can be used. Using chlorine will bleach and disinfect but it will
not have any long term effect. If chlorine is used, it must be
completely neutralized before painting.
- On porous and absorbant surfaces, a borax solution can be used.
This will not bleach the mildew but will act as a disinfectant
and also has the added benefit of having a long term effect on
preventing mold when left on the surface when absorbed into the
substrate. Borax is used prior to painting. Alternate solutions
are the use of ammonia.
Sometimes, you have to repaint a surface after the mold is removed.
There is always a risk of the mildew reappearing especially after
a severe mildew outbreak. In these situations, the surface needs
to be carefully cleaned before repainting.