ASTM D3456-86(2002)
(Practice)Standard Practice for Determining by Exterior Exposure Tests the Susceptibility of Paint Films to Microbiological Attack
Standard Practice for Determining by Exterior Exposure Tests the Susceptibility of Paint Films to Microbiological Attack
SIGNIFICANCE AND USE
The growth of fungi and algae in and on the surface of paint films represents a major cause of discoloration or disfigurement of painted surfaces. This practice covers the preparation of coatings for testing, their application on substrates, and the arrangement of the coated panels on exterior test fences to determine the degree of microbiological attack that may occur on the surface of the coatings over a period of time. This practice is intended to provide guidelines for, and a discussion of, the various factors critical in selection of exterior coatings resistant to discoloration or disfigurement by algae and fungi.
SCOPE
1.1 This practice provides guidelines for determining the susceptibility of paint films to microbiological attack on exterior exposure. While it is recognized that various organisms may occur on an exposed coating, the specific types of organisms are mainly of academic interest. The degree to which microbiological discoloration occurs is the primary concern.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D3456–86(Reapproved2002)
Standard Practice for
Determining by Exterior Exposure Tests the Susceptibility
of Paint Films to Microbiological Attack
This standard is issued under the fixed designation D 3456; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope exposed to other conditions. These factors include the geo-
graphic location, local atmospheric conditions such as the dust
1.1 This practice provides guidelines for determining the
and pollen content of the air, angle of exposure, degree to
susceptibility of paint films to microbiological attack on
which the coating is subjected to weathering, effects of
exterior exposure. While it is recognized that various organ-
moisture and sunlight, the substrates on which the coating is
isms may occur on an exposed coating, the specific types of
applied, and the coatings in the paint system under test. The
organisms are mainly of academic interest. The degree to
latterfactorincludesthestabilityofthecoatingwhilepackaged
which microbiological discoloration occurs is the primary
in the container, as well as the composition of the coatings
concern.
included in the total system and the thickness of each coating
1.2 The values stated in SI units are to be regarded as the
applied. Thus, while microorganisms occur on the surface of
standard. The values given in parentheses are for information
the last film applied, the degree of microbiological growth that
only.
will occur is also influenced by the composition of the
1.3 This standard does not purport to address all of the
undercoats. All the above factors should be considered in the
safety concerns, if any, associated with its use. It is the
selection of a coating resistant to discoloration by microorgan-
responsibility of the user of this standard to establish appro-
isms.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Significance and Use
2. Referenced Documents 4.1 The growth of fungi and algae in and on the surface of
paint films represents a major cause of discoloration or
2.1 ASTM Standards:
disfigurement of painted surfaces. This practice covers the
D 1006 Practice for Conducting Exterior Exposure Tests of
preparation of coatings for testing, their application on sub-
Paints on Wood
3 strates, and the arrangement of the coated panels on exterior
D 1849 Test Method for Package Stability of Paint
test fences to determine the degree of microbiological attack
D 3274 Test Method for Evaluating Degree of Surface
that may occur on the surface of the coatings over a period of
Disfigurement of Paint Films by Microbial (Fungal or
time. This practice is intended to provide guidelines for, and a
Algal) Growth or Soil and Dirt Accumulation
discussionof,thevariousfactorscriticalinselectionofexterior
3. Summary of Practice
coatings resistant to discoloration or disfigurement by algae
and fungi.
3.1 Simple observation of a coated object subjected to
exterior exposure is considered a practical and reliable method
5. Preparation and Application of Coatings
for determining the degree that microorganisms discolor the
5.1 Conditioning of Coatings Prior to Application—
coating. However, this applies to a specific coated object
Individual coatings to be used in the paint system should be
exposed under a given set of conditions. It should be recog-
properly aged under suitable conditions prior to testing. Hy-
nized that there are critical factors that influence the amount of
drolysis, amalgamation, absorption, and other physical and
fungal growth that may occur on the same coated object when
chemical changes that may have a profound influence on the
resistance of a coating to microorganisms usually increase with
This practice is under the jurisdiction of ASTM Committee D01 on Paint and increasing temperature. It is recognized that actual storage
Related Coatings, Materials, and Applications and is the direct responsibility of
periods of paints prior to use may vary from one to several
Subcommittee D01.28 on Biodeterioration.
years, and the peak temperature encountered may be as warm
Current edition approved March 27, 1986. Published May 1986. Originally
e1
as 160°F (70°C). However, a recommended conditioning
published as D 3456 – 75. Last previous edition D 3456 – 75 (1981) .
Annual Book of ASTM Standards, Vol 06.01.
period consists of 1 year at room temperatures or 1 month at
Annual Book of ASTM Standards, Vol 06.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D3456–86 (2002)
125°F (50°C) as in Test Method D 1849. The conditioning of Industrial coatings should be evaluated on the surface for
coatings prior to testing shall be agreeable to the producer and which they are designed. Trade sales and industrial mainte-
the user in the case of a referee test.
nance coatings are general-purpose coatings and should per-
5.2 Preparation of Coatings for Application—Prior to ap-
form on a variety of substrates. For such coatings, test
plicationofthevariouscoatingstobeincludedinthetotalpaint
exposures on the following substrates are recommended for the
system, thoroughly reconstitute each coating by appropriate
indicated reasons.
mixing or shaking.At the time of application, there must be no
6.2 Wood Substrates—Sapwood of pine and fir generally is
settling, incompatibility, or other stability problem observable
considered conducive to growth of microorganisms. This may
in the coating in the container.
be due to nutrients in the wood and to the low dimensional
5.3 Application of Paint System—Apply each coating in the
stability, resulting in microcracking of coatings applied on the
total paint system in an appropriate manner to provide a
wood with subsequent mold growth in these cracks. Plywood,
specified and reasonably uniform film thickness. The presence
hardboard, and other wood-derived products support varying
and thickness of different coatings in the complete system can
degrees of fungal growth depending on the nutrient value,
have a pronounced effect on the degree of microbiological
degree of moisture absorption, and dimensional stability of the
discoloration that will occur. Thus, each paint in the system
base material. Redwood tends to have better dimensional
must be applied as recommended by the manufacturer. It is
stability and otherwise has insignificant effect on the micro-
important that the procedure and the user agree on the type of
biological growth on coatings applied over it. Cedar lumber
coatings and the spreading rate of each coating in the final test
generally contains compounds that aid in resisting microbio-
film. The drying time between coats and the curing time of the
logical growth. Both cedar and redwood contain colored
total system prior to exposure should also be specified.
extractives that can bleed through coatings to discolor the
Recommended practice for house paint is 2 days between coats
surface. Some of these extractives can also be nutrients that
andnolessthan7daysandnotlongerthan1monthpriortothe
contribute to microbiological growth, resulting in added dis-
exterior exposure. Industrial and industrial maintenance coat-
coloration.
ings may require a different practice that should be acceptable
6.3 MetalSubstrates—Iron, galvanized steel, and aluminum
to the producer and the user.
5.4 . On each substrate use a test area not less than 310 are common substrates for paints. Iron and zinc compounds
2 2
generally inhibit microbiological growth. On the other hand,
cm (48 in. ) in size. When only one type of substrate is being
used, expose at least duplicate panels. When more than one thesemetalsmayreactwithcertainmicrobiocidestoreducethe
substrate is employed for each exposure condition, duplicate microbiological inhibition. Certain microbiocides can also
panels of each substrate are not usually required. In case of a cause discolored corrosion products or loss of adhesion by the
referee test, it is recommended that replication and size of test coating on these surfaces.Aluminum is rather chemically inert
area be agreed on between the producer and the user. Common
and does not itself promote microbiological growth. It may,
practice in the industry is to use 152 by 915-mm (6 in. however, cause loss of microbiological resistance of coatings
(nominal) by 36-in.) panels for house paint exposures and to
containing certain mercury compounds because of the amal-
use 305-mm (12-in.) metal panels of various widths for
gamationreactionbyaluminumandmercury.Thiscanresultin
exposures of industrial and industrial maintenance coatings.
loss of adhesion.
6.4 Masonry Substrates—The extremes of masonry sur-
6. Substrates for Testing
faces gene
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.