ASTM D4414-95(2007)
(Practice)Standard Practice for Measurement of Wet Film Thickness by Notch Gages
Standard Practice for Measurement of Wet Film Thickness by Notch Gages
SIGNIFICANCE AND USE
Wet film thickness measurements of coatings applied on articles can be very helpful in controlling the thickness of the final dry coating, although in some specifications the wet film thickness is specified. Most protective and high performance coatings are applied to meet a requirement or specification for dry film thickness for each coat or for the completed coating system, or for both.
There is a direct relationship between dry film thickness and wet film thickness. The wet film/dry film ratio is determined by the volume of volatiles in the coating as applied, including permitted thinning. With some flat coatings the dry film thickness is higher than that calculated from the wet film thickness. Consequently, the results from the notch gage are not to be used to verify the nonvolatile content of a coating.
Measurement of wet film thickness at the time of application is most appropriate as it permits correction and adjustment of the film by the applicator at the time of application. Correction of the film after it has dried or chemically cured requires costly extra labor time, may lead to contamination of the film, and may introduce problems of adhesion and integrity of the coating system.
The procedures using notched gages do not provide as accurate or sensitive measurements of wet film thickness as do the Interchemical and Pfund gages described in Test Methods D 1212. Notch gages may, however, be used on nonuniform surfaces, like concrete block, that are too rough to use the Interchemical and Pfund gages. Also notched gages can be very useful in the shop and field for determining the approximate thickness of wet films over commercial articles where size(s) and shape(s) are not suitable for measurements by other types of gages. Examples of such items are ellipses, thin edges, and corners.
An operator experienced in the use of a notched gage can monitor the coating application well enough to ensure the minimum required film thickness will be obtained.
App...
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 Test Methods D 1212.
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 m (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 m (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.
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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4414 − 95 (Reapproved2007)
Standard Practice for
Measurement of Wet Film Thickness by Notch Gages
This standard is issued under the fixed designation D4414; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice describes the use of thin rigid metal
D1212 Test Methods for Measurement of Wet Film Thick-
notched gages, also called step or comb gages, in the measure-
ness of Organic Coatings
ment of wet film thickness of organic coatings, such as paint,
varnish, and lacquer.
3. Summary of Practice
1.2 Notched gage measurements are neither accurate nor
3.1 The material is applied to the articles to be coated and
sensitive, but they are useful in determining approximate wet
the wet film thickness measured with a notched gage.
filmthicknessofcoatingsonarticleswheresize(s)andshape(s)
3.2 Procedure A—A square or rectangular thin rigid metal
prohibit the use of the more precise methods given in Test
gage with notched sides, having tabs of varying lengths, is
Methods D1212.
pushed perpendicularly into the film. After removal from the
1.3 This practice is divided into the following two proce-
film, the gage is examined and the film thickness is determined
dures:
to lie between the clearance of the shortest tab wet by the film
1.3.1 Procedure A—A square or rectangular rigid metal
and the clearance of the next shorter tab not wetted by the film.
gage with notched sides is used to measure wet film thick-
3.3 Procedure B—A circular thin rigid metal gage having
nesses ranging from 3 to 2000 µm (0.5 to 80 mils 1). Such a
spaced notches of varying depths around its periphery is rolled
gage is applicable to coatings on flat substrates and to coatings
perpendicularly across the film. After removal from the film,
on articles of various sizes and complex shapes where it is
the gage is examined and the film thickness is determined as
possible to get the end tabs of the gage to rest in the same plane
being between the clearance of the deepest face wetted and the
on the substrate.
clearance of the next deepest notch face not wetted by the film.
1.3.2 ProcedureB—Acircular thin rigid metal notched gage
is used to measure wet film thicknesses ranging from 25 to
4. Significance and Use
2500 µm (1 to 100 mils ). Such a gage is applicable to coatings
4.1 Wet film thickness measurements of coatings applied on
onflatsubstratesandtocoatingsonobjectsofvarioussizesand
articles can be very helpful in controlling the thickness of the
complex shapes.
final dry coating, although in some specifications the wet film
1.4 The values stated in SI units are to be regarded as the thickness is specified. Most protective and high performance
coatings are applied to meet a requirement or specification for
standard. The values given in parentheses are for information
only. dry film thickness for each coat or for the completed coating
system, or for both.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 4.2 There is a direct relationship between dry film thickness
and wet film thickness. The wet film/dry film ratio is deter-
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- mined by the volume of volatiles in the coating as applied,
including permitted thinning. With some flat coatings the dry
bility of regulatory limitations prior to use.
film thickness is higher than that calculated from the wet film
thickness. Consequently, the results from the notch gage are
not to be used to verify the nonvolatile content of a coating.
This practice is under the jurisdiction of ASTM Committee D01 on Paint and
Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.23 on Physical Properties of Applied Paint Films. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2007. Published June 2007. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1984. Last previous edition approved in 2001 as D4414 – 01 (2001). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D4414-95R07.
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4414 − 95 (2007)
aluminum (Note 1). Nonmetallic gages shall not be used.
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.
FIG. 1 Rectangular Notched Gage
7.1.2 As an example, the tabs on one row of a gage may
differ in length as follows:
4.3 Measurement of wet film thickness at the time of By 13 µm (0.5 mil) between 0 to 150µm(0and6 mils),
By 25 µm (1 mil) between 150 to 250 µm (6 and 10 mils),
application is most appropriate as it permits correction and
adjustment of the film by the applicator at the time of By 50 µm (2 mils) between 250 to 750 µm (10 and 30 mils),
and
application. Correction of the film after it has dried or
chemically cured requires costly extra labor time, may lead to By 125 µm (5 mils) over 750 µm (30 mils).
contamination of the film, and may introduce problems of
8. Procedure
adhesion and integrity of the coating system.
8.1 Apply the coating material to a rigid substrate and test
4.4 The procedures using notched gages do not provide as
withthegageimmediately.Thegagemustbeusedimmediately
accurate or sensitive measurements of wet film thickness as do
following application of the coating. Some coatings lose
the Interchemical and Pfund gages described in Test Methods
solvents quickly and spray application increases the speed.The
D1212. Notch gages may, however, be used on nonuniform
resulting rapid reduction in wet film thickness can cause
surfaces, like concrete block, that are too rough to use the
misleading readings.
Interchemical and Pfund gages. Also notched gages can be
very useful in the shop and field for determining the approxi-
8.2 Locate an area sufficiently large to permit both end tabs
mate thic
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