1、Designation: D5235 13Standard Test Method forMicroscopical Measurement of Dry Film Thickness ofCoatings on Wood Products1This standard is issued under the fixed designation D5235; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、 year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of dry filmthickness of coatings applied to a smooth, textured or cur
3、vedrigid substrate of wood or a wood-based product1.2 This test method covers the preparation of wood orwood-based specimens for the purpose of microscopical mea-surement of dry film thickness.1.3 This test method suggests an interpretation of dry filmthickness of coatings on wood or wood-based prod
4、ucts whenporous substrates are coated.1.4 This test method suggests an interpretation of dry filmthickness of coatings on wood or wood-based products whensubstrate attached or non-attached fibers occur in the dry film.1.5 The values stated in inch-pound units are to be regardedas standard. The value
5、s given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to estab
6、lish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Some specifichazards statements are given in Section 7 on Hazards.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 dry film thickness, nthat layer of thickness
7、 of driedcoating above the microscopically visible board surface thatalso comprises attached fibers but excludes free fibers that areencapsulated in the layer itself.2.1.2 edge face, nthat part of the specimen that is a planeperpendicular to the surface showing a cross section of thecoating and subs
8、trate.2.1.3 soak in, nrefers to a coating on a porous substratewhere the coating does not lie essentially on the surface of thewood or wood-based product, but has penetrated into the fiberstructure of the wood or wood-based material.2.1.3.1 DiscussionWood or wood-based products are gen-erally of a p
9、orous nature; sometimes exhibiting uniformabsorption of coatings. Frequently absorption of coatings is ofa nonuniform nature and influenced by localized surfacedensity differences or wood pore size. These conditions ofcoating absorption are commonly referred to as soak in.3. Summary of Test Method3.
10、1 A specimen of coated wood or wood-based product iscut to convenient size and edge polished with sandpaper.3.2 The polished edge of the specimen is viewed through acalibrated microscope in order to measure dry film thickness.3.3 Suggestions regarding interpretation of dry film thick-ness on porous
11、wood or wood-based material are offered.3.4 Suggestions regarding interpretation of dry film thick-ness on wood or wood-based material that have attached orencapsulated fibers in the coating are offered.4. Significance and Use4.1 The dry film thickness of coatings on wood or wood-based products is s
12、pecified in written product warranties forproper decorative and protective performance of coatings onwood or wood-based products.4.2 The minimum and maximum dry film thickness ofcoatings is recommended by coating companies for satisfactorydecorative and protective performance on wood or wood-basedpr
13、oducts.4.3 The average dry film thickness of coatings on wood orwood-based material may be used by manufacturing compa-nies to calculate theoretical cost of applied coatings. Bycomparison with actual cost, utilization efficiency may becalculated.4.4 The ratio of peak to valley dry film thickness on
14、texturedproducts is used as an indication of coating uniformity.4.5 Specific coated product requirements may dictate cer-tain film thickness determinations to be made. Discussions1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applicatio
15、ns and is the direct responsibility ofSubcommittee D01.52 on Factory Coated Wood Products.Current edition approved Nov. 1, 2013. Published December 2013. Originallyapproved in 1992. Last previous edition approved in 1997 as D5235 97 which waswithdrawn January 2006 and reinstated in November 2013. DO
16、I: 10.1520/D5235-13.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1between buyer and seller may be advisable to accommodateproduct needs relative to dry film thickness.5. Apparatus5.1 Calibrated Monocular Microscope2, equipped with a
17、noptical system3providing sufficient resolution of 0.1-mil (2.54-m) dry film thickness. One system consisting of a 16-mmobjective and a 10-power filar micrometer eyepiece, resultingin a magnification of at least 100 diameters, has been foundsatisfactory. Other combinations of objectives and eyepiece
18、sand other magnifications may also be suitable, although mag-nifications above 200 diameters may result in distortion of theviewed cross section.5.2 Source of Oblique Illumination, for the microscope.5.3 Cutoff Saw.5.4 Belt or Disc Sander.5.5 C-Type Clamp.6. Materials6.1 200 and 600-Grit Sand Paper.
19、6.2 Mold, such as a paper cup, aluminum weighing dish, ora 2 in. (50.8 mm) or larger diameter plastic pipe that is at least1 in. (25.4 mm) high.6.3 Source of Sanding Adhesive, which is used as encapsu-lating medium such as:6.3.1 Hot Melt Glue,6.3.2 Fast-Cure Acrylic Mounting Kit4, and6.3.3 Epoxy.6.4
20、 Solvent-borne Tint Dispersion, which is compatible withthe sanding adhesive.6.5 Mineral Oil.6.6 Automotive Red Transmission Oil.6.7 Zinc Stearate Powder.7. Hazards7.1 Use saws and sanders with goggles, dust mask, andproper machine safeguards to prevent injury to body limbs.7.2 Solvent-based tint di
21、spersions and adhesives may beflammable and contain toxic solvents. See manufacturersinstructions for use and proper disposal.8. Procedure8.1 Specimen Preparation:8.1.1 Select the desired coated area of a wood or wood-based material that is to be measured for dry film thickness.With the cutoff saw,
22、cut off a sample at least 112 in. (38.1 mm)wide from this area.8.1.2 Cut this specimen to a length that is at least12 in. (12.7mm) less than the inside diameter of the mold to be used.8.1.3 Place the specimen, with the sample edge to bemeasured, face down and approximately centered in the mold.8.1.4
23、 Prepare the sanding adhesive according to the manu-facturers direction for use. A dispersed pigment may be addedto the adhesive for better microscopic contrast between the dryfilm and the adhesive.8.1.5 Pour the sanding adhesive around the sample in themold and allow to harden according to the manu
24、facturersdirections.8.1.6 Remove the mold from the hardened and encapsulatedspecimen edge.8.1.7 Using a disc sander, belt sander or 200-grit sandpapermounted on a glass plate, sand the edge face of the encapsu-lated specimen to be measured until the edge face is relativelysmooth. Maintain the edge f
25、ace of the specimen as flat aspossible during sanding. Avoid heat buildup of the sandingadhesive by intermittent sanding if necessary.8.1.8 Polish the edge face of the rough sanded specimen asfollows:8.1.8.1 Mount a piece of 600-grit sandpaper on a flat glassplate. Rub the edge face of the rough san
26、ded specimen over the600-grit sandpaper in one direction, then reverse direction by180 for several more rubs. Zinc stearate powder can besprinkled on the 600-grit sandpaper or the 600-grit sandpapercan be wetted with mineral oil to produce a highly polishededge face free of scratches.8.1.9 To improv
27、e the microscopic contrast between thecoating and the wood or wood-based product, wipe a light filmof mineral oil or automotive red transmission oil across thepolished edge face with a clean cotton rag or equivalent.8.1.10 Some coatings and substrates are hard enough thatencapsulation with a sanding
28、 adhesive is not necessary. Al-though in all cases, use of the encapsulating sanding adhesivewill lead to the sharpest microscopic edge face and the highestdegree of accuracy.8.1.11 Some laboratories find that a mold for the specimenencapsulation with sanding adhesive is not necessary. In thiscase t
29、wo specimens are prepared with the cut off saw. Thesanding adhesive after proper mixing is generously applied tothe coated face of each specimen, the specimens are placedtogether and a C-clamp is used to squeeze out some of thesanding adhesive. The C-clamp is not removed until thesanding adhesive ha
30、s hardened.8.2 Measurement for the Microscopic Dry Film Thickness ofthe Polished Edge Face of the Specimen:8.2.1 Place the polished edge face under the microscopelens.8.2.2 Adjust the illuminating light at a convenient obliqueangle.8.2.3 Focus the 10-power filar micrometer eyepiece on oneside of the
31、 dry film thickness spot to be measured.8.2.4 Advance 10-power filar micrometer so as to reach theother side of the spot to be measured in 8.2.3.8.2.5 Read the micrometer and calculate the dry film thick-ness by multiplying the distance in millimetres or inches per2Consult the microscope manufacture
32、rs operational manual for the correctcalibration procedure.3Video microscope instruments are available that are also capable of the requiredresolution and measurement accuracy.4The sole source of supply of this item known to the committee at this time isBuehler Ltd., 41 Waukegan Rd., P. O. Box 1, La
33、ke Bluff, IL 60044. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.D5235 132drum division on the micrometer by the n
34、umber of drumdivisions in the reading by the calibration factor.8.2.6 Multiply the calculated number in 8.2.5 by 1000 forEnglish units (39.37 for metric units), for conversion to a dryfilm thickness in mils.8.2.7 Porous substrates tend to have the coating soaked intothe open fiber structure of the w
35、ood or wood-based product. Aclear demarcation line between substrate and coating is notdiscernible. In this case, it is suggested that film thickness isthat layer of dry film thickness above the microscopicallyvisible board surface that also comprises attached fibers butexcludes free fibers that are
36、 encapsulated in the layer itself (seeFig. 1, Fig. 2 and Fig. 3).8.2.8 Several microscope companies have advanced opticalsystems and useful accessories for measuring dry film thick-ness of coatings on properly prepared coated wood or wood-based specimens. The use of their equipment for the measure-m
37、ent of dry film thickness on wood or wood-based products ishighly recommended. The directions for use of the equipmentare specific to each microscope company. Closely follow themanufacturers instructions.9. Report9.1 Report the dry film thickness of the spot to be measuredin mils or microns.9.2 For
38、textured substrates, report the following information(see Fig. 4):9.2.1 The dry film thickness in the valleys,9.2.2 The dry film thickness on the shoulders or slopes,9.2.3 The dry film thickness on the peaks,9.2.4 The dry film thickness on the flat areas if any, and9.2.5 Optionally some laboratories
39、 report the ratio of thepeak to valley dry film thickness or the average of multiple dryfilm readings of one or all of these substrate areas.9.3 For woods with large pores ignore the soak in of coatinginto the wood pore or cell and report only the dry film thicknessabove the microscopically visible
40、board surface (see Fig. 5).10. Precision and Bias10.1 The precision and bias for this test method are primar-ily dependent upon each operator choosing exactly the samespot on the polished specimen for measurement.10.2 The precision and bias statements will be developed inround-robin testing.11. Keyw
41、ords11.1 coated wood or wood-based product; dry film thick-ness; microscopic measurementFIG. 1 Illustrates Film Thickness above the Wood Surface wherethe Coating Layer Encapsulates Free Wood FibersFIG. 2 Illustrates Film Thickness with Wood Fibers Attached tothe Wood Surface and Surrounded by a Coat
42、ing LayerFIG. 3 Illustrates Coating Soak In, not Reportable as FilmThicknessFIG. 4 Illustrates the Peaks, Shoulders (Slopes), Valleys and FlatAreas of a Textured SubstrateFIG. 5 Illustrates Film Thickness on Wood Substrates with LargePoresD5235 133ASTM International takes no position respecting the
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44、subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Head
45、quarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This sta
46、ndard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D5235 134
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