TOLERANCES
The numerical information quoted on marine product datasheets has
been derived from laboratory test data obtained under controlled
conditions for the products described. Whilst every effort has been
made to ensure accuracy, this information will be subject to minor
variations obtained in normal manufacturing tolerances, and any
fluctuations in ambient conditions during the application and curing
periods.
GLOSS LEVEL
Typical gloss values have been determined in accordance with ISO
2813:1994/Corr 1:1997 using a 60° gloss head or, for North America,
ASTM-D-523. The categories used in the data sheet are:
Finish (Sheen)
Matt
Eggshell
Semi-Gloss
Gloss
High Gloss
DRY FILMTHICKNESS
(DFT)
The measured thickness of the final dried film applied to the substrate.
WET FILMTHICKNESS
(WFT)
The initial thickness of the wet coating applied to the substrate.
VOLUME SOLIDS
The volume solids figure given on the product data sheet is the
percentage of the wet film, which remains as the dry film, and is
obtained from a given wet film thickness under specified application
method and conditions. These figures have been determined under
laboratory conditions using a modification of the test method described
in ISO 3233:1998/Corr 1:1999 – Determination of Volume Solids by
Measurement of Dry Film Density. The modification is technically
equivalent involving the use of slightly smaller glass slides. For North
America, volume solids are measured by ASTM-D-2697 (1986) which
determines the volume solids of a coating using the recommended dry
film thickness of the coating quoted on the product data sheet, and a
specified drying schedule at ambient temperature, i.e. 7 days at 25°C +
1°C.
DRYING TIME
The drying times quoted in the product data sheet have been
determined in the laboratory using a typical dry film thickness, the
ambient temperature quoted in the relevant product data sheet, and the
appropriate test method
Touch Dry
(ISO 1517 - 1973)
- The surface drying state of a coating
when Ballotini (small glass spheres) can
be lightly brushed away without
damaging the surface of the coating.
Hard Dry
(ISO 9117-1990)
- The condition of the film in which it is
dry throughout its thickness, as
opposed to that condition in which the
surface of the film is dry but the bulk of
the coating is still mobile.
This through drying state is determined by the use of a “mechanical
thumb” device “in situ” at the temperature quoted.
In North America the Touch Dry, Hard Dry and Re-coat times are
determined in accordance with ASTM-D-1680 (1995) using sections
7.5, 7.7 and 7.8 respectively.
The drying times achieved in practice may show some slight fluctuation,
particularly in climatic conditions where the substrate temperature
differs significantly from the ambient air temperature and because of
variations in practical dry film thickness.
OVERCOATING INTERVAL
The product data sheet gives both a “minimum” and a “maximum”
overcoating interval and the figures quoted at the various temperatures
are intended as guidelines, consistent with good painting practices.
Certain terms require elaboration as follows:
Minimum
The “minimum overcoating time” quoted is an indication of the time
required for the coating to attain the necessary state of dryness and
hardness to allow the application of a further coat of paint without the
development of any film irregularities such as lifting or loss of adhesion
of the first coat (ASTM-D-1640).
It assumes:
(i) the coating has been applied at the normal recommended
thickness.
(ii) environmental conditions both during and after application were
as recommended for that particular coating, especially in
respect of temperature, relative humidity and ventilation.
(iii) the paint used for overcoating is suitable for that purpose.
(iv) an understanding of the “method of application”. For example, if
a coating can be applied by both brush or spray it is expected
that overcoating may be carried out more rapidly if sprayed and
it is the “lowest” figure that is quoted.
If the above conditions are not met, the quoted minimum overcoating
times are liable to variation and will invariably have to be extended.
Maximum
The “maximum overcoating time” indicates the allowable time period
within which overcoating should take place in order to ensure
acceptable intercoat adhesion is achieved.
Extended
Where an “extended” overcoating time is stated, the anticipated level of
intercoat adhesion can only be achieved if:
(i) the coating has been applied in accordance with good painting
practices and at the specified film thickness.
(ii) the aged coating has the “intended” surface characteristics
required for long term overcoatability. For example, an overapplied
epoxy MIO may not have its usual “textured” surface
and will no longer be overcoatable after ageing unless it is
abraded.
(iii) the coating to be overcoated must be intact, tightly adherent,
clean, dry and free from all contaminants. For example, the
leached layer on an antifouling coating is usually porous and
friable and must be removed to provide the necessary surface
for overcoating.
(iv) coatings having a glossy surface which could have a detrimental
effect on the adhesion of subsequent coats should be treated by
light surface abrasion, sweep blasting, or other suitable
processes which will not cut through or detract from the
performance of the underlying coating.
(v)in some situations, and with specific products, it may be
necessary to high pressure fresh water wash prior to
overcoating.
It should be recognised that the level of intercoat adhesion obtained is
also dependent upon the chemisty of the “topcoat”. By their nature,
primers or undercoats will have inherently better adhesion than finish
coats.
The measurement of ultimate “adhesion strength” can often be a difficult
process, and interpretation of results can be subjective. Excellent
adhesion does not necessarily mean good performance, nor does
relatively poor adhesion necessarily mean poor performance.
Although the adhesion of coatings applied to aged / cured coatings may
be deemed satisfactory for the specified end use, actual numerical values
obtained for adhesion may be less than with coatings applied within
“minimum / short” overcoating intervals.
FLASH POINT
The minimum temperature at which a product, when confined in a
Setaflash closed cup, must be heated for the vapours emitted to ignite
momentarily in the presence of a flame (ISO 3679:1983). In North
America Flash Point is determined in accordance with ASTM-D-3278
VOLATILE ORGANICCOMPOUND (VOC)
VOC content is the weight of volatile organic compounds which
participate in atmospheric photochemical reactions for litre of paint.
Legislative requirements differ from country to country, and from region to
region, and are constantly being reviewed. Values quoted for VOC on
the product data sheet are calculated from the product formulation.
WORKING POT LIFE
The maximum time during which the product supplied as separate
components should be used after they have been mixed together at the
specified temperature.
The values quoted have been obtained from a combination of laboratory
tests, and application trials, and refer to the time periods under which
satisfactory coating performance will be achieved.
Application of any product after the working pot life has been exceeded
will lead to inferior product performance, and must NOT be attempted,
even if the material in question appears liquid in the can.
SHELF LIFE
The shelf life quoted on the product datasheets is generally a
conservative value, and it is probable that the coating can be applied
without any deterioration in performance after this period has elapsed.
Exceeding the shelf life of a product does not necessarily render it
unusable. However, if the specified shelf life has been exceeded, it is
recommended that the condition of the material is checked before any
large scale application is undertaken using materials beyond the quoted
shelf life.
