ASTM D4414-95(2001)
(Practice)Standard Practice for Measurement of Wet Film Thickness by Notch Gages
Standard Practice for Measurement of Wet Film Thickness by Notch Gages
SCOPE
1.1 This practice describes the use of thin rigid metal notched gages, also called step or comb gages, in the measurement of wet film thickness of organic coatings, such as paint, varnish, and lacquer.
1.2 Notched gage measurements are neither accurate nor sensitive, but they are useful in determining approximate wet film thickness of coatings on articles where size(s) and shape(s) prohibit the use of the more precise methods given in Methods D1212.
1.3 This practice is divided into the following two procedures:
1.3.1 Procedure A--A square or rectangular rigid metal gage with notched sides is used to measure wet film thicknesses ranging from 3 to 2000 µm (0.5 to 80 mils 1). Such a gage is applicable to coatings on flat substrates and to coatings on articles of various sizes and complex shapes where it is possible to get the end tabs of the gage to rest in the same plane on the substrate.
1.3.2 Procedure B--A circular thin rigid metal notched gage is used to measure wet film thicknesses ranging from 25 to 2500 µm (1 to 100 mils ). Such a gage is applicable to coatings on flat substrates and to coatings on objects of various sizes and complex shapes.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.5 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.
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Designation:D4414–95(Reapproved2001)
Standard Practice for
Measurement of Wet Film Thickness by Notch Gages
This standard is issued under the fixed designation D 4414; 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 (ε) indicates an editorial change since the last revision or reapproval.
1. Scope D 1212 Test Methods for Measurement of Wet Film Thick-
ness of Organic Coatings
1.1 This practice describes the use of thin rigid metal
notched gages, also called step or comb gages, in the measure-
3. Summary of Practice
ment of wet film thickness of organic coatings, such as paint,
3.1 The material is applied to the articles to be coated and
varnish, and lacquer.
the wet film thickness measured with a notched gage.
1.2 Notched gage measurements are neither accurate nor
3.2 Procedure A—A square or rectangular thin rigid metal
sensitive, but they are useful in determining approximate wet
gage with notched sides, having tabs of varying lengths, is
filmthicknessofcoatingsonarticleswheresize(s)andshape(s)
pushed perpendicularly into the film. After removal from the
prohibit the use of the more precise methods given in Methods
film, the gage is examined and the film thickness is determined
D 1212.
to lie between the clearance of the shortest tab wet by the film
1.3 This practice is divided into the following two proce-
and the clearance of the next shorter tab not wetted by the film.
dures:
3.3 Procedure B—A circular thin rigid metal gage having
1.3.1 Procedure A—A square or rectangular rigid metal
spaced notches of varying depths around its periphery is rolled
gage with notched sides is used to measure wet film thick-
perpendicularly across the film. After removal from the film,
nesses ranging from 3 to 2000 µm (0.5 to 80 mils 1). Such a
the gage is examined and the film thickness is determined as
gage is applicable to coatings on flat substrates and to coatings
being between the clearance of the deepest face wetted and the
on articles of various sizes and complex shapes where it is
clearance of the next deepest notch face not wetted by the film.
possible to get the end tabs of the gage to rest in the same plane
on the substrate. 4. Significance and Use
1.3.2 ProcedureB—Acircularthinrigidmetalnotchedgage
4.1 Wet film thickness measurements of coatings applied on
is used to measure wet film thicknesses ranging from 25 to
articles can be very helpful in controlling the thickness of the
2500 µm (1 to 100 mils ). Such a gage is applicable to coatings
final dry coating, although in some specifications the wet film
onflatsubstratesandtocoatingsonobjectsofvarioussizesand
thickness is specified. Most protective and high performance
complex shapes.
coatings are applied to meet a requirement or specification for
1.4 The values stated in SI units are to be regarded as the
dry film thickness for each coat or for the completed coating
standard. The values given in parentheses are for information
system, or for both.
only.
4.2 There is a direct relationship between dry film thickness
1.5 This standard does not purport to address all of the
and wet film thickness. The wet film/dry film ratio is deter-
safety concerns, if any, associated with its use. It is the
mined by the volume of volatiles in the coating as applied,
responsibility of the user of this standard to establish appro-
including permitted thinning. With some flat coatings the dry
priate safety and health practices and determine the applica-
film thickness is higher than that calculated from the wet film
bility of regulatory limitations prior to use.
thickness. Consequently, the results from the notch gage are
not to be used to verify the nonvolatile content of a coating.
2. Referenced Documents
4.3 Measurement of wet film thickness at the time of
2.1 ASTM Standards:
application is most appropriate as it permits correction and
adjustment of the film by the applicator at the time of
1 application. Correction of the film after it has dried or
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
chemically cured requires costly extra labor time, may lead to
Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Current edition approved Nov. 10, 1995. Published January 1996. Originally
ε1 2
published as D 4414 – 84. Last previous edition D 4414 – 84 (1990) . Annual Book of ASTM Standards, Vol 06.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D4414–95 (2001)
NOTE 1—Aluminum or aluminum alloy gages are more easily distorted
and may exhibit greater wear than steel gages. Gages made of plastic or
deformable metal are not suitable.
7.1.1 Each notched side shall consist of a series of tabs
(between notches) varying in length and located in a line
between two end tabs equal in length and longest in the row.
7.1.2 As an example, the tabs on one row of a gage may
FIG. 1 Rectangular Notched Gage
differ in length as follows:
By 13 µm ( 0.5 mil) between 0 to 150 µm (0 and 6 mils),
By 25 µm (1 mil) between 150 to 250 µm (6 and 10 mils),
contamination of the film, and may introduce problems of
By 50 µm (2 mils) between 250 to 750 µm (10 and 30 mils),
adhesion and integrity of the coating system.
and
4.4 The procedures using notched gages do not provide as
By 125 µm(5 mils) over 750 µm (30 mils).
accurate or sensitive measurements of wet film thickness as do
the Interchemical and Pfund gages described in Methods
8. Procedure
D 1212. Notch gages may, however, be used on nonuniform
surfaces, like concrete block, that are too rough to use the
8.1 Apply the coating material to a rigid substrate and test
Interchemical and Pfund gages. Also notched gages can be
withthegageimmediately.Thegagemustbeusedimmediately
very useful in the shop and field for determining the approxi-
following application of the coating. Some coatings lose
mate thickness of wet films over commercial articles where
solvents quickly and spray application increases the speed.The
size(s) and shape(s) are not suitable for measurements by other
resulting rapid reduction in wet film thickness can cause
types of gages. Examples of such items are ellipses, thin edges,
misleading readi
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