1、Designation: D8008 15Standard Practice forRepresentative Field Sampling of Traffic Paints1This standard is issued under the fixed designation D8008; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numbe
2、r in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers procedures for obtaining represen-tative field samples of mixed or unmixed waterborne,solventborne, or other liquid tra
3、ffic paints from drums, totes, ormachine striping tanks. Traffic paint samples are often takenfrom storage containers in the field by paint suppliers orgovernment agencies for laboratory testing to determine prod-uct quality and/or for approvals prior to striping. It is importantthat the samples tak
4、en are “representative” (have a compositionreflecting the overall composition in the container). Althoughtraffic paints can remain homogeneous for weeks or months,some will stratify over time and become non-homogeneous.Obtaining a representative sample can be challenging particu-larly in a field env
5、ironment. The desired method for obtaininga liquid sample is to thoroughly mix the sample until homo-geneous and then sample the mixture from the top. If completemixing cant be verified then an alternative practice is to obtaina sample using a liquid tube sampling device. These deviceshave the abili
6、ty to capture a top-to-bottom core of paint fromthe container. Inner or outer rod tube samplers are recom-mended for sample extraction. The inner rod tube sampler isthe preferred sampler.1.2 The practice selected for representative sampling shouldhave written agreement between the parties providing
7、theproduct and those testing the product.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to addres
8、s all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D562 Test Method
9、 for Consistency of Paints MeasuringKrebs Unit (KU) Viscosity Using a Stormer-Type Viscom-eterD1475 Test Method For Density of Liquid Coatings, Inks,and Related ProductsD3925 Practice for Sampling Liquid Paints and RelatedPigmented CoatingsD5495 Practice for Sampling With a Composite LiquidWaste Sam
10、pler (COLIWASA)2.2 ISO Documents:3ISO 1513 Paints and varnishes Examination and prepa-ration of test samplesISO 15528 Paints, varnishes, and raw materials for paintsand varnishes Sampling3. Terminology3.1 The following terms apply to this practice:3.1.1 COLIWASA (composite liquid waste sampler), nat
11、ube type device that is typically used as a zone sampler formany types of liquids.3.1.2 composite core sampler, na compartmented tubetype sampler that is potentially capable of obtaining a repre-sentative core sample.3.1.3 core sample, na sample extracted from a containertop-to-bottom with a tube ty
12、pe device.3.1.4 liquid scoop, na type of liquid thief sampler withcompartments and slide closure that potentially can be used toobtain a representative core sample3.1.5 liquid thief sampler, na tube or scoop device used toextract a liquid sample.1This practice is under the jurisdiction of ASTM Commi
13、ttee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.44 on Traffic Coatings.Current edition approved July 1, 2015. Published August 2015. DOI: 10.1520/D8008-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orco
14、ntact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyrigh
15、t ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.6 pigment settling/pigment sedimentation, nincreasein pigment concentration toward the bottom of a container overtime mainly due to the effects of gravity.3.1.7 representative sample, na pai
16、nt sample taken from athoroughly mixed container, or a paint sample taken by suitablemeans from a partially mixed or unmixed container that has acomposite composition equivalent to that of a thoroughlymixed container.3.1.8 stratification, nseparation of a mixture of materialsinto layers based on den
17、sity.3.1.9 syneresis, na clear liquid separation at the top of apaint typically resulting from movement of lower densitycontinuous phase components upward in a paint.3.1.10 uniform sample, nsee representative sample.3.1.11 water float, nsmall amount of water added to thetop of a tote or drum of fast
18、-dry waterborne traffic paint toprevent skinning.3.1.12 zone sampler, na sampling device that samplesfrom a selected location within a container; a zone samplerproduces a non-representative sample unless the containercontents are homogeneous.4. Summary of Practice4.1 This practice provides methods f
19、or obtaining “represen-tative” traffic paint samples from storage containers in the field.4.2 Traffc PaintTraffic paints are essentially pigmentdispersions consisting of a continuous phase, a polymericbinder, finely ground pigments (typically white or yellow), andvarious additives in small amounts s
20、uch as a pigmentdispersant, thickener, defoamer, and biocide. The continuousphase in a typical waterborne traffic paint is water with smalleramounts of methanol and/or coalescing solvent, and the binderis a synthetic latex. The continuous phase for solventbornetraffic paint is one or more organic so
21、lvents, and the binder istypically an alkyd resin.4.3 Traffc Paint ContainersThe paint containers mostoften sampled in the field are drums, totes, or striping machinetanks. Common traffic paint tote sizes are 250 gal (946 L), 275gal (1040 L), or 330 gal (1249 L), and they are typically ofplastic (po
22、ly) or stainless steel construction. The heights ofstandard containers are: 55 gal drums, 34 in (86 cm); 250 galtotes, 40 in. (102 cm); 275 gal totes, 46 in. (117 cm); and 330gal totes, 54 in. (137 cm). Striping tank containers vary in size.Tube type sampling devices should be long enough to reach t
23、hebottom of the container being sampled.4.4 Field SamplingGovernment agencies such as Depart-ments of Transportation (DOTs) often conduct field samplingof traffic paints from containers for laboratory testing todetermine the paints conformity to specifications and forapproval before application to a
24、 roadway. Suppliers alsosometimes sample field containers if there is an issue reportedor a quality check is needed. The sample size typically requiredfor laboratory testing is on the order of about 1 qt to 1 gal (1to 4 L).4.5 Change in Paint Composition over TimeLike mostother types of liquid paint
25、s, traffic paints are very uniformwhen first made in production and also initially in the storagecontainers when shipped out into the field for striping. Thepaints can be very stable and homogeneous for weeks ormonths. However, depending on a paint formulations inherentstability, the paints viscosit
26、y, its storage environment (internaland external), and time in storage, traffic paint in a containermay change composition from top to bottom over time. Thechange in paint uniformity within a container is often simplydue to the effect of gravity resulting in the gradual downwardsettling or sedimenta
27、tion of the more dense pigments and/ormigration of lower density continuous or disperse phasecomponents upward toward the surface. Pigment settling isminimized in the production of traffic paint with a sufficientgrind (reduction of pigment particle size), proper stabilization(with optimized dispersa
28、nts and surfactants) and also byincreasing the viscosity of the paint to within specification witha thickener. An eventual non-homogeneous composition ofpaint within a container is often a vertical gradient distributionof pigment with a corresponding gradient change in solidscontent (lower at the to
29、p and higher at bottom of the container).Over time, this can produce soft settling at the bottom of thecontainer, or in more extreme cases, hard settling (compaction)may occur. Sometimes the continuous phase components(solvents or water) being of lower density can migrate upwardtoward the surface of
30、 the container eventually resulting in aclear liquid separation at the top (syneresis). Another contribu-tor to non-uniformity of waterborne traffic paint in a containeris the common practice of adding a small “water float” on topof the paint after filling to prevent skinning. Paint in containersexp
31、osed to extreme heat, to long periods of elevatedtemperature, or to one or more freeze-thaw cycles may haveaccelerated compositional changes. Obtaining representativesamples from non-homogeneous paint containers are addressedin this practice.4.6 Sampling MethodsPractice D3925 addresses proce-dures f
32、or the mixing of liquid paints of any type and in mostany size container to obtain representative samples for testing.In that method, thorough mixing of the paint is verified whendensities match for zone samples taken from the top andbottom of the container. With the availability of appropriatemixin
33、g equipment and a suitable power source, the proceduresin Practice D3925 can be used for sampling traffic paint in thefield. Since sample uniformity is assured when thoroughmixing is achieved, this is a preferred option. However, mixingis often not practical or even possible in a field environment,a
34、nd complete mixing may not be verifiable. In this situation, analternative preferred practice is to obtain a representativesample using a liquid thief device that has the ability to capturea top-to-bottom core of paint that is representative whenhomogenized. The core sample would include any water f
35、loatbut would typically not include any hard sediment if present.ISO 15528 provides general procedures and various types ofdevices for sampling liquids and solids. However, many of thesampling devices described in ISO 15528 are zone samplersand therefore not capable of capturing a representative pai
36、ntsample. This practice describes the particular issues involvedD8008 152with the field sampling of traffic paint and best practices forobtaining representative samples from mixed or unmixedcontainers.5. Significance of Practice5.1 For quality assessment and/or approval for use of trafficpaint store
37、d in the field, it is often necessary to obtain arepresentative sample for testing. Correct sampling of trafficpaint is a skilled operation, and if not properly conducted withthe right equipment and procedures, a sample may inadver-tently fail one or more specification tests when evaluated by atesti
38、ng laboratory. Among the test results that could be affectedare solids content, resin content, TiO2content, heat-agestability, freeze-thaw stability, and dry time.Any of these couldinadvertently result in non-approval or penalties.6. Apparatus and Procedures6.1 Sampling from Thoroughly Mixing Contai
39、ners:6.1.1 Thorough Mixing with VerificationA most preferredpractice for obtaining a representative sample from a containeris thorough mixing of the container contents prior to sampling.Practice D5495 provides guidelines for types of mixers, sampleremoval, and verification for thorough mixing. Some
40、types ofmixers that can be used are impellers, drum rollers, and drumshakers, or the practice of “boxing” where fluid is pumpedback and forth between containers for mixing. With PracticeD5495, complete mixing is indicated when a sample pulledfrom the top of a container has a density very close to a
41、samplepulled from the bottom of the container within 0.5 lb/gal (60g/L). Density is typically determined using a weight/gal cup inaccordance with Test Method D1475. If available, efficientmixing can be accomplished using a high speed portable drumor tote mixer. The mixer should have sufficient power
42、, largeimpeller blades, and shaft long enough to reach the bottom ofthe container and ideally into the corners of the container. Asmall blade mixer or under-powered mixer may not produceenough mixing action to efficiently turn over the contents of thecontainer. The mixer can be driven by air, electr
43、icity, orhydraulics but should be appropriate for efficiently movingviscous fluids (traffic paints) of moderately high viscosity.Traffic paint viscosity is commonly measured with a StormerType viscometer using Practice D562, and a typical viscosityrange is 75 to 95 Krebs Units (KU). Over time, the v
44、iscosity oftraffic paint can increase or decrease during storage, and theviscosity near top of the container may be different (usuallylower) than that near the bottom.6.1.2 Samplers for Thoroughly Mixed ContainersIf thereis assurance (by density comparison or other means) that acontainers contents h
45、ave been thoroughly mixed, a represen-tative sample can be removed using a wide variety of samplingdevices from most any location within the container. One suchdevice is a zone sampler. The zone sampler takes a samplefrom a single location within a container. The recommendedsampling location for zon
46、e sampling of a thoroughly mixedcontainer is near the horizontal/vertical center of the container.As noted in 6.1.1, zone samples taken from top and bottom willconfirm homogeneity with a density match. Some commonexamples of zone samplers are bottle or can samplers, dipsamplers, or bottom zone sampl
47、ers as shown in ISO 15528sections 5.1.4 and 5.15. Various tube type samplers such as aCOLIWASA can also be used as zone samplers.6.1.3 Sampling from an Outlet ValveIf there is an outletvalve at the bottom of the container (some totes and tanks), athoroughly mixed container can be sampled through thi
48、s port.When sampling from an outlet valve, some paint, about 5 gal(about 20 L) should first be drained from the container into aclean bucket before getting the final sample for testing. Theusual sample size for testing is approximately 1 qt to 1 gal (1to 4 L). Any drained material in the bucket not
49、used for testingcan be returned to the top of the container.6.2 Sampling from Unmixed Containers or when Mixingmight be Incomplete:6.2.1 Often it is not possible to conduct mixing of fielddrums, totes, or striping tanks before obtaining a sample fortesting. In those instances, a tube or closed scoop samplingdevice that has the ability to capture a representative paint“core” from top to bottom of the container is required. Ifundisturbed, the contents of a container may vary from top tobottom for the reasons discussed in 4.4. However, the compo-sition wit
