NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
`Contact ASTM International (www.astm.org) for the latest information
`
`Designation: D 5795 – 95 (Reapproved 2000)
`
`Standard Test Method for
`Determination of Liquid Water Absorption of Coated
`Hardboard and Other Composite Wood Products Via
`“Cobb Ring” Apparatus1
`
`This standard is issued under the fixed designation D 5795; 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 (e) indicates an editorial change since the last revision or reapproval.
`
`3.1.2.1 Discussion—The C.U. factor is calculated as fol-
`lows:
`
`C.U. Factor 5
`
`100
`Area ~ring! 5
`
`100
`pr 2
`
`(1)
`
`1. Scope
`1.1 This test method is intended to serve as a means for
`measurement of liquid water that passes through a wetted paint
`film, and which is subsequently absorbed and retained by the
`underlying wood substrate. Alternative techniques for the use
`of the “Cobb Ring” apparatus are described.
`1.2 The values stated in SI units are to be regarded as the
`standard. The values given in parentheses are for information
`only.
`1.3 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 appro-
`priate safety and health practices and determine the applica-
`bility of regulatory limitations prior to use.
`
`2. Referenced Documents
`2.1 ASTM Standards:
`D 1193 Specification for Reagent Water2
`E 177 Practice for the Use of the Terms Precision and Bias
`in ASTM Test Methods3
`E 691 Practice for Conducting an Interlaboratory Study to
`Determine the Precision of a Test Method3
`
`3. Terminology
`3.1 Definitions of Terms Specific to This Standard:
`3.1.1 Cobb unit (C.U.), n—The weight of distilled water
`absorbed by the underlying wood substrate in grams per 645
`cm2(100 in.2 ) of surface area (discounting additional areas
`contributed by texturing or grooves) per 24-h time period.
`3.1.2 Cobb unit (C.U.) factor, n—a dimensionless math-
`ematical term which, for a given ring size, may be multiplied
`times the weight change after 24 h to calculate the Cobb unit
`value.
`
`C.U. Factor 5
`
`5
`
`100
`12.56
`
`where:
`r = radius
`For example, for 101.6-mm (4-in.) inside diameter ring.
`or
`100
`3.14~2!2
`3.1.3 composite wood products—boards or other structured
`or decorative materials manufactured from wood fibers, flakes
`or strands and various resin binders.
`3.1.3.1 Discussion—One example is hardboard.
`3.1.4 hardboard—a generic term for a panel manufactured
`primarily from interfelted lignocellulose fibers consolidated
`under heat and pressures in a hot press to density of at least 31
`lbs (13.95 kg) per cubic foot (cubic meter).4
`
`5 7.96
`
`(2)
`
`4. Summary of Test Method
`4.1 Suitable size rings of metal or plastic are adhered or
`clamped to the flat, coated surface of composite wood panels to
`be tested.
`4.2 The assembly is equilibrated at a constant temperature
`and humidity and weighed.
`4.3 The weighed assembly is placed on horizontal5 surface
`in a controlled temperature and humidity room or environmen-
`tal chamber. Water is placed in the ring and left in contact with
`the board face for 24 h.
`4.4 After 24 h the remaining water is removed from the ring,
`the assembly blotted dry and reweighed.
`
`1 This test method is under the jurisdiction of ASTM Committee D-1 on Paint
`and Related Coatings, Materials, and Applications and is the direct responsibility of
`Subcommittee D01.52 on Factory-Coated Wood Products.
`Current edition approved Oct. 10, 1995. Published December 1995.
`2 Annual Book of ASTM Standards, Vol 11.01.
`3 Annual Book of ASTM Standards, Vol 14.02.
`
`4 “Today’s Hardboard”, American Hardboard Association, 1210 W. Northwest
`Highway, Palatine, IL 60067.
`5 The specification of a solid, continuous horizontal surface or a discontinuous
`(wire rack, expanded metal, etc.) is required. Surface must be consistent from
`laboratory to laboratory since this can influence the rate of evaporation of moisture
`and, thus, retention of moisture and Cobb values.
`
`Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
`
`1
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`Louisiana-Pacific Corporation, Exhibit 1006
`IPR of U.S. Pat. No. 8,474,197
`Page 1
`
`

`

`4.5 The increase in weight of the assembly due to water
`uptake is calculated by simple subtraction and then converted
`to Cobb units through the use of the C.U. factor (see 3.1.2 ).
`
`8.2 Caulking compounds may be flammable and contain
`toxic solvents. See manufacturer’s instructions for proper use
`and disposal.
`
`D 5795 – 95 (2000)
`
`5. Significance and Use
`5.1 This test method provides a simple quantitative measure
`of water absorption by coated composite wood products.
`Although primarily used to evaluate factory-primed composite
`wood products, this test method may be of service for other
`wood substrates and coating systems.
`5.2 This test method has demonstrated utility for composite
`wood siding products ranging in thickness from approximately
`6.35 to 25.4 mm (1⁄4 to 1 in.). Extension of this test method to
`wood substrates of other types and thickness may be useful.
`5.3 Conditioning of substrate, coated sample preparation,
`application method, dry film thickness, cure conditions, and
`number of replicate specimens should be agreed upon between
`the purchaser and the supplier of the coating material.
`5.4 Such measurements are used as indicators or predictors
`of the anticipated performance of coated composite wood
`products during exterior exposure. They may be used for
`developmental evaluation of coatings, substrates, or both. They
`may also be useful for quality control or monitoring of the
`production of coated composite wood products.
`
`6. Apparatus
`6.1 Rings, may be cut from stainless steel, aluminum or
`PVC pipe. The ring diameter can be any size, but useful results
`have been obtained with rings of 101.6 mm (4 in.) or larger6
`inside diameter, wall thickness of 9.53 mm (3⁄8 in.) and height
`of 25.4 mm (1 in.).
`6.2 Environmental Chamber, set at 23 6 2°C (73 6 4°F)
`and 50 6 5 % relative humidity, or other agreed upon options.
`6.3 Saw, suitable for cutting of samples.
`6.4 Caulk Gun or Applicator, or, a clamp and gasket device
`for holding the ring tightly against the board is needed.
`6.5 Balance, with sufficient capacity (typically 400 g) and
`0.01-g accuracy.
`
`7. Materials
`7.1 Butyl or Silicone Caulk, which has been determined not
`to contribute to assembly weight change through absorption of
`water or interaction with the coating.
`7.2 Distilled Water, (see Specification D 1193).
`7.3 Test Boards, appropriately identified, coated or un-
`coated,7 cut to a square size that is 25.4 mm (1 in.) greater than
`the ring diameter. A minimum of three replicates is recom-
`mended.
`7.4 Control Samples, coated or uncoated without rings will
`also be required. These will be used to assess the degree of
`equilibration that is achieved.
`
`8. Hazards
`8.1 Use saws with goggles, dust mask, and proper machine
`safeguards to prevent injury.
`
`9. Procedure
`9.1 Sealing of Rings to the Coated Face of the Samples:
`9.1.1 A continuous bead of caulk is applied to one edge of
`the ring. The caulked side of the ring is then attached to the
`sample with gentle pressure and a slight twisting motion; to
`maintain an accurate and uniform test area, only minor caulk
`“squeeze-out” should occur inside of the ring. Carefully wipe
`out this minor caulk“ squeeze-out” to prevent errors in later
`calculations.
`9.1.2 Alternatively, the assembly may be produced with a
`clamp and gasket device.8 Satisfactory results can also be
`obtained from clamp and gasket devices that are of self design
`and locally produced by any machine shop.
`9.1.3 To inhance reproducibility, do not generate data by a
`combination of the caulk procedure and the clamp and gasket
`procedure.
`9.1.4 Also, for improved reproducibility, all rings must be of
`the same nominal internal diameter.
`9.2 Equilibration:
`9.2.1 Allow the samples with rings and controls without
`rings to equilibrate for seven days at 23 6 2°C (73 6 4°F) and
`50 6 5 % relative humidity.
`9.3 Initial Weighing:
`9.3.1 Weigh (grams) the controls and samples with rings to
`the nearest 0.01 g; record the weight.
`9.4 Fill each ring with the volume of distilled water required
`to achieve a depth of 12.7 6 3.2 mm (1⁄2 6 1⁄8 in.) of distilled
`water.
`9.5 Store test assemblies at the same conditions used for
`equilibrating the panels.
`9.6 Final Weighing:
`9.6.1 After 24 h, pour out the water and blot the surface
`inside the ring completely dry with a soft paper towel.
`Immediately weigh (grams); record the new weight of the
`samples with rings.
`9.6.2 After all measurements from 9.6.1 have been com-
`pleted, weigh (grams) and record the weights of the control
`boards without rings. Compare the weights with the initial
`weights. If the weight change of the control boards is more
`than 20 % of the weight change of the test boards, the absolute
`values of the test results may be questionable.
`9.7 Additional Procedures:
`9.7.1 Caulked rings can be removed from the coated boards
`by pulling the ring from the board and cleaning in lacquer
`solvent.
`9.7.2 For textured boards without a groove in the coated
`panel, apply additional caulk to the outside of the ring to get a
`satisfactory seal after attaching the ring to the coated board.
`
`6 Rings of 01.6 to 254.0 mm (4 to 10 in. 1) are commonly used.
`7 The use of the uncoated test boards is not intended for direct comparison with
`the coated samples, but may be used to ascertain the substrate variability and suggest
`the number of replicates needed.
`
`8 The sole source of supply of clamp and gasket devices known to the committee
`at this time is the Teledyne Gurley Cobb Sizing Tester, T.M.I., 400 Bay View Ave.,
`Amityville, NY 11701. If you are aware of alternative suppliers, please provide this
`information to ASTM Headquarters. Your comments will receive careful consider-
`ation at a meeting of the responsible technical committee,1 which you may attend.
`
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`Louisiana-Pacific Corporation, Exhibit 1006
`IPR of U.S. Pat. No. 8,474,197
`Page 2
`
`

`

`D 5795 – 95 (2000)
`
`Material
`
`24-h
`Average,
`gm/100 in.2
`
`TABLE 1 Precision
`Reproducibility,
`Standard
`Deviation,
`SR
`
`Repeatability,
`Standard
`Deviation, Sr
`
`Repeatability
`Limit, Y
`
`Reproducibility
`Limit, R
`
`E
`C
`A
`D
`B
`
`5.225
`6.629
`7.185
`14.020
`20.545
`
`0.851
`1.780
`2.256
`1.055
`1.146
`
`0.880
`1.917
`2.398
`1.596
`2.117
`
`2.38
`4.98
`6.32
`2.95
`3.21
`
`2.46
`5.37
`6.72
`4.47
`5.93
`
`9.7.3 For boards with a groove in the coated board, attach
`the ring to the board so that at least one groove length will be
`the same as the diameter of the ring. Apply extra caulk in the
`groove at the appropriate spot before attaching the ring in order
`to get a good seal. Extra caulk may have to be applied in the
`groove outside the ring after attaching the ring in order to get
`a good seal.
`9.7.4 During equilibration and testing of the boards with
`rings, store the boards test side up and single high on a flat
`surface that is impervious to moisture.
`the control
`9.7.5 If an environmental chamber is used,
`boards with ring assemblies must not be stacked upon each
`other. It is recommended that the control boards and ring
`assemblies be stored coated side up and single high on wire
`racks at least 50.8 mm (2 in.) above or below adjacent rings.
`Care must be taken so as not to overload the humidity chamber
`with rings containing water.
`
`10. Calculations
`10.1 Calculate and record the weight change by subtraction
`of the initial weight of 9.3.1 from the final weight of 9.6.1.
`10.2 Calculate the Cobb unit (C.U.) factor for the ring sizes
`used (see 3.1.2.1).
`10.3 Multiply the C.U. factor times the weight change
`recorded in 10.1.1 and record the Cobb unit values for the
`samples.
`
`10.4 Average, then record the replicate results.
`
`11. Precision and Bias 9
`11.1 Precision—Interlaboratory Test Program—An inter-
`laboratory study of Hardboard Siding “Cobb Ring” water
`permeability was conducted in accordance with Practice E 691
`in seven laboratories with five materials, with each laboratory
`obtaining seven test results for each material (see Table 1).
`11.1.1 The terms repeatability limit and reproducibility limit
`in Table 1 are used as specified in Practice E 177.
`11.1.2 Some of the deviations in Table 1 are believed due to
`the concern expressed in 4.3, 9.1.3 and 9.1.4. This will be
`addressed in a future round robin.
`11.2 Bias—Since there is no accepted reference material,
`method, or laboratory suitable for determining the bias for the
`procedure in this test method, no statement on bias is being
`made.
`
`12. Keywords
`12.1 absorption; coated hardboard; Cobb ring; composite
`wood products
`
`9 Supporting data are available from ASTM Headquarters. Request RR:
`D01–1093.
`
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`in this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk
`of infringement of such rights, are entirely their own responsibility.
`
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`if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards
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`
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`United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the above
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`through the ASTM website
`(www.astm.org).
`
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`Louisiana-Pacific Corporation, Exhibit 1006
`IPR of U.S. Pat. No. 8,474,197
`Page 3
`
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