Performance of
`southern
`OSB overlaid with
`resin-impregnated
`paper
`
`Evangelos
`
`J. Biblis
`
`Abstract
`
`oriented
`strandboard
`of southern
`The performance
`paper was
`(OSB) panels overlaid with resin-impregnated
`evaluated
`according to 1) cerLain APA-performance
`stan-
`21-day water-spraying
`dards for siding that
`included
`on
`the overlay; 2) edge weather_tbility
`of ANSI-AHA A135.6
`standards;
`and 3) certain physical
`and mechanical
`tests
`of ASTM D 1037. The results obtained indicate
`that phe-
`nolic resin-impregnated
`paper overlays can be bonded suc-
`cessfully to OSB made of southern
`pine and ]hardwood
`mixtures with a bond stronger
`than the internal bond
`
`pa-
`strength of the OSB substrate. The resin-impre_,mated
`per, when overlaid onto one surface of the OSB substrate,
`can provide
`a structural
`improvement
`of between
`10 and
`15 percent
`for various mechanical
`properties.
`"When OSB
`paper are appro-
`panels overlaid with resin-impregnated
`swel-
`priately primed, painted,
`and edge-sealed,
`thickness
`ling and checking ofthe drip edge, after exposure to 21-day
`continuous water-spraying,
`can be controlled effectively
`is kept d:ry. Under
`if the back surface
`these conditions,
`however,
`the overlaid surface becomes
`rough with unde-
`sirable visual effects known as "telegraphing,"
`which are
`of swollen flakes in the overlayer without
`protrusions
`rup-
`turing the overlay. Telegraphing
`cannot be eliminated
`or
`controlled with application
`of primers
`or paints. More
`work is needed to solve the problem of telegraphing
`of the
`overlaid surface,
`
`In 1988, 50.1 percent of the U.S. structural wood panels
`(OSB)) was manufac-
`(plywood and oriented strandboard
`tured in the South, primarily
`of southern
`yellow pine (2).
`13,609 million ft. 2
`In that
`same year,
`the South produced
`(3/8-in. basis) of structural
`panels; of these, 11.9 billion i_.2
`was southern pine plywood and 1.7 billion ft. 2was OSB (2).
`For the same period,
`the total
`annual
`structural
`panel
`production in the United States was 27.2 billion fl:.2(3/8-in.
`base), comprised of 22.6 billion ft) softwood plywood and
`4.6 billion ft. 2nonveneered
`panels
`(waferboard
`and OSB).
`It has been forecasted
`that production
`capacity :forstruc-
`rural panels will increase in t]he South in the form of non-
`
`of the lower
`to take advantage
`in order
`panels
`veneered
`underutilized
`costs and to utilize the currently
`production
`species (3). Although
`the majority of southern
`hardwood
`hardwoods consists of high density species (oaks and hick-
`ories), OSB manufacturers
`presently
`utilize mixtures
`of
`southern
`pine and medium density hardwoods,
`especially
`ye:Llow-poplar and sweetgum.
`It appears
`that
`as long as
`medium and low density hardwoods
`are available
`in the
`South,
`they will be preferred
`for manufacture
`of OSB in-
`stead of the high density hardwoods.
`
`commercial OSB panels in the South are
`Presently,
`produced from mixtures
`of southern
`pine and sweetgum,
`wilLh approximately
`3 to 5 percent
`liquid phenolic
`resin,
`in 7/16-inch thickness,
`and with densities between
`40 to
`
`45 pcf. These panels
`in
`used as sheathing
`are primarily
`housing and are significantly
`heavier
`than equal
`thick-
`ness panels of southern
`pine plywood and aspen wafer-
`board. They are manufactured
`to meet
`the APA perform-
`ance standards
`for structural
`panels
`(3).
`structural
`More uses have to be found for southern
`fleJkeboards in order to increase utilization
`of the changing
`resources,
`to keep the present
`and future mills producing
`at full capacity,
`and to manufacture
`panels with added
`value. Extending
`the uses of the structural
`flakeboard
`panels will require the development of panels with higher
`strength, dimensional
`stability, and durability for exterior
`uses.New uses couldincludepanels for house siding,con-
`crete forms, and other
`industrial
`and agricultural
`exterior
`uses.
`
`need to
`the following panel properties
`For such uses,
`be :improved:
`thickness
`swelling at edges, edge checking,
`
`is a Professor of Wood Utilization and Technol-
`The author
`ogy, School of Forestry and Alabama Agri. Expt. Sta., Auburn
`Univ., AL 36849-5418. This study was supported by McIntire-
`Stennis fund_,,project 952, and is published as Alabama Agri.
`Expt. Sta. J. Series No. 9-892225P. This paper was received for
`publication in August 1989.
`©Forest Products Research Society 1990.
`Forest Prod. J. 40(4):55-62.
`
`FOREST PRODUCTS JOURNAL
`
`VoL40,No.4
`
`55
`
`Louisiana-Pacific Corporation, Exhibit 1021
`IPR of U.S. Pat. No. 8,474,197
`Page 1
`
`

`

`of the panels
`integrity
`and structural
`surface roughness,
`and temperature
`varia-
`after being subjected to humidity
`tions encountered
`in normal use. To obtain improved panel
`qualities,
`it will be necessary to 1) increase the phenolic
`resin level
`in the board; 2) overlay one or both panel sur-
`faces with resin-impregnated
`stabi-
`paper; and 3) better
`lize the panel edges.
`Numerous
`studies have dealt with the effect of various
`processing variables on the physical and engineering
`prop-
`erties of particleboards
`and structural
`flakeboards. Board
`density, density profile, and compaction ratio are proper-
`ties that
`influence board strength and thickness
`swelling
`with changes
`in moisture
`content
`(9,12,17,18).
`Other factors that
`influence mechanical
`and physical
`properties,
`as well as durability
`of structural
`flakeboards,
`are the resin type and characteristics,
`atomization during
`blending, and percentage
`of resin applied to the furnish.
`investigators
`reported an increase in flexural prop-
`Several
`erties and internal
`bond (IB) strength with increased phe-
`nolic resin content
`in the board (10,:[6,18,21,22).
`In many
`cases,
`the rate of strength
`increase
`decreased
`at resin lev-
`els above 6 percent. The reported results do not indicate
`an optimum adhesive
`level. All of the previously men-
`tioned studies that
`indicate an increase in strength prop-
`erties with increasing
`liquid phenolic
`resin also indicate
`a reduction in percent of thickness
`swelling with increas-
`ingresinlevel.
`flakeboard is its
`property of structural
`An important
`durability,
`i.e., ability to retain a high percentage
`of its
`original properties
`for a long time under the environmental
`conditions
`expected in use. These ,service conditions
`in-
`volve fluctuations
`of temperature
`from below freezing (0 °
`to 5°F) to approximately
`water boiling (212 ° to 220°F),
`fluctuations
`in relative
`humidity
`(.RH) from a low of 15
`to 20 percent up to 100 percent,
`and rainfall
`(a condition
`for high water absorption).
`labora-
`there are several
`In this country and Canada,
`to simu-
`tory methods
`available
`for exposing specimens
`lated weathering
`or accelerated
`a_,dng, and others
`that
`simply expose specimens
`to wet-dry cycling via temper-
`ature and vacuum-pressure
`variations.
`These tests eval-
`uate flakeboard
`durability
`by determining
`dimensional
`of board specimens after
`changes and retention of strength
`exposure. Several
`investigators
`have either used or eval-
`uated a number of these methods
`(11-15,19,20). It has been
`thai; none of the methods
`stated by several
`investigators
`alone simulates
`long-term outdoor natural weathering,
`Surface irregularities
`(roughness)
`of structural
`flake-
`boards increase
`after wetting and even after exposure
`to
`a high RH (90% to 95%), especially
`if followed by redry-
`ing. It has been reported that surface smoothness depends
`on particle geometry (particularly
`thickness),
`the resin
`type and level used, species, moist_tre, and other proces-
`sing factors. Surface roughness
`can be aesthetically
`un-
`acceptable
`and can cause surface degradation
`as well as
`increase moisture
`or water
`absorption,
`thus
`leading to
`increased thickness
`swelling. It has been stated that paper
`overlays improve retention
`of board properties
`(15). It has
`also been demonstrated
`that overlays improve the appear-
`ance, performance,
`and durability
`of exterior plywood and
`particleboard
`(5-7). Performance
`of overlays varies
`con-
`
`siderably depending upon the type of overlay and the resin
`system used (8). One group of overlays includes pigmented
`films, another
`group includes
`resin-treated
`fiber-facings,
`and a third group includes paper overlays
`impregnated
`with phenolic, polyester,
`or melamine;
`resins.
`Scope
`of the
`study
`The overall objectiveofthis research was to evaluate
`the performance
`of smooth-surface
`southern OSB panels
`overlaid with resin-impregnated
`paper used as siding, and
`to determine
`the technical
`factors and variables
`influenc-
`ing their performance.
`It should be pointed out that when this study was ini-
`tiated, performance standards
`for nonveneer panel siding
`did not exist. Presently,
`however,
`such a standard
`does
`exist (3). In addition,
`there is an American National Stan-
`dard for hardboard
`siding (A135.6) (1).
`This study was concerned with all aspects of the be-
`havior and performance
`of overlaid panels as siding. How-
`ever, it concentrated on those critical properties
`that were
`posing serious questions
`as to the performance
`of these
`
`panels as siding.
`The study consists of four experiments, which are con-
`cerned with the evaluation
`of certain properties or the
`effects of materials
`and processes on panel properties
`and
`behavior.
`Experiment1
`the bond-
`I was designed to 1) determine
`Experiment
`ing quality of the resin-impregnated
`paper
`to the OSB
`2) verify the paper manufacturers'
`substrate;
`recommen-
`dations
`related to bonding variables;
`and 3) determine
`certain
`physical
`and mechanical
`properties
`of the over-
`laid panels according to ANSI/AHA A135.6 standards
`for
`hardboard
`siding.
`Two full-size commercial OSB panels (4 ft. by 8 ft. and
`0.450 in. thick) from each of three southern OSB mills
`were used for this experiment. Each of these panels was
`cut into four 24- by 24-inch sections and two sections 24
`inches by 48 inches. Only the 24- by 24-.inch sections were
`used in this experiment. The four 24- by 24-inch sections
`from each panel were overlaid on one s:[dewith Simpson's
`MEDEN No. 32:[ paper,
`a Kraft paper
`impregnated
`by
`the manufacturer with 35 percent
`thermosetting
`phenolic
`resin. The back side of the overlay sheet has a coating of
`thermosetting
`phenolic
`resin to form s, glueline
`designed
`for hot-press
`bonding
`to the substrate
`panel. The total
`weight of the paper with glue is 75 lb./Mft._, and its thick-
`ness is 0.018 inch. Overlaying was done in a 25- by 30-inch
`laboratory
`press using 0.085-inch steel cauls, and the as-
`semblies were pressed at 285°F and 200 psi for 6-1/2 min-
`utes. After overlaying,
`the sections were cut into speci-
`mens for the following tests:
`swelling, ASTM
`1. Water absorption
`and thickness
`D 1037, Part B (4:).From each full-size panel of each mill,
`three 12-by 12-inch specimens, paper-overlaid
`on one side,
`were used for this test. Specimens were originally
`condi-
`tioned to equilibrium at 65 percent RH and 72°F and the
`weight,
`thickness,
`length,
`and width of each specimen
`was measured. Then specimens were watersoaked
`for 24
`hours and their weight,
`thickness, width, and length were
`remeasured. Water absorption was expressed as a percent-
`
`56
`
`APRIL1990
`
`Louisiana-Pacific Corporation, Exhibit 1021
`IPR of U.S. Pat. No. 8,474,197
`Page 2
`
`

`

`Treatment
`no.
`
`1
`2
`3
`4
`5
`6
`7
`
`TABLE 1. -- Treatments
`
`used in experiment 3.
`
`Surface finish
`
`Drip edge sealer
`
`Primer
`
`Oil-basedprimer
`Oil-based primer
`Oil-based primer
`Oil-based primer
`Oil-based primer
`Oil-based primer
`Oil-based primer
`
`Overcoat
`
`Enamelpaint
`Oil paint
`Glossy ext. latex
`Epoxy paint
`Epoxy resin
`Enamel paint
`Oil paint
`
`Primer
`
`Epoxypaint
`Epoxy paint
`Epoxy paint
`Epoxy paint
`Epoxy paint
`Epoxy resin
`Epoxy resin
`
`Overcoat
`
`Enamelpaint
`Oil paint
`Glossy ext. latex
`Epoxy paint
`Epoxy resin
`Enamel paint
`Oil paint
`
`swelling was ex-
`age of the original weight. Thickness
`thickness,
`pressed as a percentage
`of the original
`2. Weatherability
`of overlaid specimens, ANSI/AHA
`A135.6-84. From each full-size panel,
`four 2- by 12-inch
`specimens, overlaid on one side (two parallel
`and two per-
`pendicular
`to face direction), were used for this test.
`3. Linear
`expansion
`(35% to 90%), ASTM D 1037.
`From each full-size panel,
`five 3- by 12-inch specimens
`overlaid
`on one side (two parallel
`and three perpendic-
`ular
`to face direction) were used for this test, according
`to ANSI/AHA A135.6.
`
`4. Flexure, ASTM D 1037, Part B. From each full-
`size panel,
`ten 3- by 6-inch specimens, overlaid on one side,
`
`load-
`were tested to failure over a 4-inch span with central
`ing, after being conditioned to equilibrium at 65 percent
`RH and 72°F. Five of the specimens were tested parallel
`to the panel's
`length and five perpendicular.
`The paper-
`overlaid surface was on the compression side.
`5. Falling ball
`impact
`test, ASTM D 1037. Specimens
`for this test were 9 by 12 inches
`in size. From each full-
`size panel,
`two specimens, overlaid on one side, were test-
`ed. The paper-overlaid
`surface receiw_d the ball
`impact,
`Specimens were conditioned to equilibrium prior to testing
`at 65 percent RH and 72°F. Resistance
`to failure from
`impact
`loading was measured
`by dropping a 2-inch-diam-
`eter steel ball on the center of the specimen while it was
`clamped between two plywood frames. After an initial
`drop of 9 inches,
`the height of the drop was increased
`by
`1-inch intervals
`until
`fracture was visible on the bottom
`surface,
`bond strength, ASTM D 1037. This test
`6. Internal
`was performed to evaluate
`the quality of bonding between
`the paper overlay and the OSB substrate. Eight specimens
`from each full-size panel were tested,
`7. Rail shear
`strength, ASTM D 1037. Six specimens
`from each full-size panel, paper-overlaid
`on one side, were
`tested
`to determine
`rail
`shear
`strength. All specimens
`were tested after being conditioned to 65 percent RH and
`72°F"
`8. Plate shear modulus, ASTM D 3044. From each
`full-size panel, one 12- by 12-inch specimen, paper over-
`laid on one side, was tested to determine
`the plate shear
`stiffness. Specimens were conditioned[ at 65 percent RH
`and 72°F prior to testing.
`Experiment 2
`swel-
`included thickness
`2, evaluation
`In experiment
`ling and checking at the panels' drip edge, panel buckling
`
`between vertical supports, wall frame expansion of framed
`full-size panels, and surface smoothness of panels (APA,
`P-11, P-12)(3). Three full-size commercial OSB panels
`(4 ft.
`by 8 ft. and 0.450 in. thick)
`from each of the three
`south-
`ern mills were used for this experiment. All nine panels
`were overlaid on one side with Simpson's MEDEN No. 321
`phenolic-impregnated
`paper with pressing done in a south-
`ern pine plywood mill. The bonding of the paper overlay
`was made in 3-1/2 minutes at 315°F under 215 psi pressure.
`The overlaid sm'faces and edges of OSB panels were
`first primed with an oil-based primer and then overcoated
`
`flat latex paint. Three pandts from each mill
`with exterior
`were each attached
`(nailed)
`to an 8-foot-.high by 12-foot-
`wide wood frame, w:hich was built with 2- by 4-inch lumber
`and had vertical supports spaced 16 inches on center
`(APA,
`P-11) (3). The top and back of each clad frame were covered
`securely with a plastic sheet
`to insure
`that no spray or
`rainwater
`reached the back side of the ,overlaid panels.
`To facilitate measurements
`of thickness
`swelling at the
`drip edges, nine cutouts (three for each panel) were made
`to water-spraying
`in the bottom plate ,ofeach frame. Prior
`the attached panels, measurements were taken of the orig-
`inal drip edge thickness
`at the three cutout points for each
`panel
`(middle and 8 in. from each corner)
`to 0.001-inch
`accuracy.
`In addition, prior to spraying,
`the original buck-
`ling between vertical
`supports of each panel
`in the frames
`was measured at middl_length
`and 12 inches from the top
`and bottom edge. Prior
`to spraying the original
`frame,
`dimensions were also measured
`at three; horizontal
`and
`three vertical
`lines defined as the distances between the
`permanentlyinsertednails on eachframe.
`A garden sprinkling hose was attached on the top of
`each frame approximately
`4 inches from the panels. After
`the initial measurements were taken,
`a thin film of water
`was sprayed onto the overlaid surface of the panels for
`21 days. Immediately
`after completion of the water-spray-
`ing,
`the following measurements
`were made,
`of drip edges at the same points as mea-
`1. Thickness
`sured originally
`for each panel;
`the same
`suppo:cts at
`2. Buckling
`between
`vertical
`location as measured
`originally for each panel;
`3. Dimensions
`of the framing assembly at the same
`original
`three horizontal
`and three vertical
`lines in each
`frame;
`4. Estimation of the percentage of "telegraphing"
`(protrusionofswollenflakes without rupturing the over-
`lay) on the overlaid surface of each panel;
`checking
`in each panel.
`5. Probe test of' drip-edge
`
`FOREST
`
`PRODUCTS
`
`JOURNAL
`
`Vol.40, No. 4
`
`57
`
`Louisiana-Pacific Corporation, Exhibit 1021
`IPR of U.S. Pat. No. 8,474,197
`Page 3
`
`

`

`3
`
`Experiment
`the results of exper-
`3 was designed after
`Experiment
`iment 2 were known.
`In this experiment,
`three types of
`primers
`and five types of coatings were applied on the
`overlaid surfaces and drip edges of small sections
`(10.5
`or 22 in. wide and 48 in. long) of overlaid OSB.
`Four full-size commercial OSB panels (4 ft. by 8 ft. and
`0.450 in. thick)
`from each of the three mills previously
`mentioned were used for this experiment. All 12 panels
`were overlaid on one side with Simpson's MEDEN No. 321
`phenolic-impregnated
`paper. Bonding was done in a south-
`ern pine plywood mill, using 3-1/2 minutes under 215 psi
`pressure at a temperature
`of 315°F. The overlaid surfaces
`of all panels were primed with an oil-based primer. Two
`full-size overlaid panels from each mill were cut into small
`sections,
`10.5 by 48 inches. One section from each panel
`was coated with one of the first
`fiw_ treatments
`listed in
`Table 1. That provided two replications
`from each mill
`and six total
`replications
`for each treatment.
`The other two full-size overlaid :panels from each mill
`were cut into sections 22 by 48 inches. Two sections, one
`with the drip edge parallel
`to flake orientation
`and the
`Other with perpendicular
`orientation,
`from the same panel
`were coated with one each of the listed treatments
`1, 2,
`6 and 7. That provided three replications
`for each treat-
`ment and for each orientation,
`swelling determination,
`For use in drip-edge thickness
`the thickness
`of drip edges of all treated
`sections were
`measured prior to exposure to 0.001-inch accuracy at mid-
`length
`and 12 inches from each corner.
`In addition,
`the
`weight of all sections 10.5 inches wide was measured
`to
`0.01 pound for water absorption determination,
`All the 10.5- by 48-inch sections (a total of 30 sections)
`were installed on a wood frame 16 feet wide by 8 feet high
`as lap-siding, using a 1-inch overlap,
`single nailing,
`and
`with the sealed drip edge of each section exposed. The side
`edges of each section were caulked to prevent water
`from
`entering the side edges and back ,_ide of the sections,
`All of the 22- by 48-inch surface-, and edge-treated
`sec-
`tions (a total of 24 sections) were installed
`on two wood
`frames 8 feet high by 12 feet wide with a 2-inch horizontal
`spacing between them. A thin plastic strip flashing was
`installed
`in the spacing. This arrangement
`permits
`the
`of small panel
`exposure
`sections
`simulating
`the use of
`full-size panels as siding rather
`than as lap siding. The
`side edges of each section were caulked to prevent water
`from entering their edges and back side. The top and back
`side of frames were covered securely with plastic
`sheet
`to insure that no spray or rainwater
`reached the back
`side ofthe sections,
`
`to the three
`attached
`to all sections
`Water-spraying
`frames was applied with garden hoses attached at the top
`of each frame approximately
`4 inches from the top sec-
`tions. The water pressure was adjusted to allow a thin
`film of water
`to cover the sections continuously for 21 days
`and nights,
`after the 21-day period. The
`Spraying was terminated
`10.5-inch-wide small sections were removed carefully from
`the frames to prevent damage. The weight of each section
`and thicknesses,
`at the previously measured
`points along
`
`the drip edges, were recorded. Probe tests of the drip-edge
`checking for each section and an estimation
`oftelegraph-
`ing were also made. The same procedure was followed for
`the 22-inch-wide sections after spraying,
`except
`that no
`water absorption was determined
`on those sections.
`Experiment
`4
`4 was designed after the results of exper-
`Experiment
`iment 3 were known. In this experiment,
`the effort to elim-
`inate or substantially
`reduce the su_ace
`irregularities
`of the overlaid surface after exposure to wetting consisted
`of overlaying
`the OSB with a factory preprimed
`resin-
`impregnated
`paper of high resin content.
`In addition,
`in
`an effort
`drip-edge checking,
`to eliminate
`a different
`for-
`mulation
`of edge sealer was used on the drip edges of the
`panels.
`
`resin-impregnated
`paper was Catalin's
`The preprimed
`is impregnated with
`Ltd., CATAPRIME-15.
`This paper
`37 percent phenolic resin. Unprimed paper weight was
`31 lb./Mft._; weight with primer was 49 lb./Mft.2; thickness
`was 0.014 inch. The back side of this paper did not have
`a dry glueline and therefore
`required
`a phenolic film for
`bonding it to the OSB substrate.
`In addition,
`this paper
`requires
`a release film to avoid sticking of the primed sur-
`face to platens or cauls in the hot-press. The edge sealer
`used was Nox-Crete Chemicals' Edge Flex, which is a car-
`boxylated copolymer, water-based, latex emulsion.
`Six full-size experimental OSB panels, 4 feet by 8 feet
`by 0.450 inch thick,
`fabricated
`from 60 percent
`southern
`yellow pine and 40 percent of a mixture
`of sweetgum and
`yellow-poplar, were used in this experiment. Three of the
`panels were from a batch with a target 4.5 percent phenol-
`ic resin solids content and the other
`three with a target
`6.5 percent phenolic resin solids content
`(10). All six pan-
`els were overlaid on one side with Catalin's CATAPRIME-
`in a southern pine plywood
`15 phenolic-impregnated
`paper
`mill. A dry phenolic resin film, 0.008 inch thick, was used
`to bond the CATAPRIME-15
`to the OSB substrate. Bond-
`ing was done in the hot-press with a press time of 5 min-
`utes and at 300°F under 200 psi pressure. Dupont's MY-
`LAR polyester
`release film was used to eliminate
`sticking
`of the primed paper surface to the press. The overlaid sur-
`faces of all panels were painted with a coat of exterior
`enamel paint and all panel edges were sealed with one
`coat of Edge Flex sealer. The drip edges received a second
`coat. Paint and sealer were left to dry for 72 hours before
`exposure
`to wetting.
`Three overlaid panels from each OSB resin level were
`nailed to a 8-foot by 12-foot wood frame built
`according
`to the APA test method (P-11) (3) and described in detail
`in experiment 2. Prior to water-spraying ofthe panels on
`
`of drip-edge thick-
`
`three measurements
`the two frames,
`ness were taken for each panel.
`On the top of each frame, a garden hose was attached
`approximately
`4 inches from the panels, and, after
`the
`initial measurements were taken, a thin film of water was
`sprayedontothe overlaidpanel surfacesfor21 days.Im-
`mediately
`after completion of water-spraying,
`the follow-
`ing measurements
`were made.
`1. Thickness of drip edges at the same points as orig-
`inally measured
`for each panel;
`
`58
`
`APRIL1990
`
`Louisiana-Pacific Corporation, Exhibit 1021
`IPR of U.S. Pat. No. 8,474,197
`Page 4
`
`

`

`checking for each panel;
`2. Probe test of drip-edge
`3. Estimation
`of the percentage
`of telegraphing
`on
`the overlaid
`surface of each panel,
`Results
`and discussion
`
`1
`Experiment
`on the physical
`treatments
`Results of experimental
`(Table 2) indi-
`properties
`of the paper-overlaid
`specimens
`cate that
`the tested specimens meet the ANSI/AHA A135.6
`requirement
`in linear swelling (paralle]D and in edge swel-
`but &)not meet require-
`ling (weatherability
`ofsubstrate),
`ments
`for water
`absorption
`and thidkness
`swelling.
`It
`should be pointed
`out
`that
`these
`requirements
`are for
`hardboard
`siding,
`properl_ies (Table 3) indi-
`Results
`for the mechanical
`cate that
`flexural
`strength (MOR) and[ ball
`impact meet
`
`the ANSI/AHA A135.6 requirements. The :[Btest indicated
`that
`the bonding of"the impregnated
`paper
`to the OSB
`substrate was very good, since all failures Lookplace with-
`in the OSB. This also verifies
`the paper
`:manufacturer's
`recommendations
`for bonding the paper
`to substrates.
`The
`results
`also indicate
`that
`the overlaid
`paper provides
`a
`structural
`reinforcement
`of approximately
`15 percent
`in
`rail shear strength and 10 percent
`in plate shear stiffness.
`
`Experiment
`2
`Results of this experiment
`the av-
`(Table 4) show that
`erage drip-edge
`swelling
`of nine panels
`from three mills
`is 25 percent, which is the maximum allowed (3). Three
`panels,
`from a total of nine tested, exceed the 25 percent
`permissible
`level.
`It is believed, however,
`that
`this was
`the result of wetting of the back side by wicking, which
`
`TABLE 2. -- Physical properties of OSB specimens overlaid on one side with resin-impregnated
`requirements, a
`to ANSI/AHA
`
`paper,
`
`tested according to ASTM D 1037, Part B, and compared
`
`OSB
`mill no.
`
`1
`2
`3
`
`Density
`(pcf)
`47.2
`40.2
`40.0
`
`Water absorption
`Thickness
`(65% RH to
`from 65% RH
`24 hr. soak)
`to 24 hr. soak
`........................................................................
`35.0
`14.6
`40.7
`15.9
`38.9
`14.2
`
`(from 30 to 90% RH)
`Linear
`Edge
`Parallel
`Perpendicular
`(weatherability)
`(%).......................................................................
`22.0
`0.16
`0.23
`14.8
`0.14
`0.25
`13.0
`0.10
`0.20
`
`aANSI]AHA A135.6 requirements: Maximum waber absorption = 15 percent; maximum thickness swell = 10 percent; maximum linear expansion = 0.40
`percent; and maximum edge swell (weatherability
`of substrate) = 25 percent.
`
`Swelling
`
`TABLE 3. -- Mechanical properties of OSB specimens overlaid on one side with resin-impregnated
`pared to ANSI/AHA
`requirements, a
`
`paper,
`
`tested according to ASTM D 1037, Part B, and com-
`
`Flexure
`
`OSB
`millno.
`
`Parallel
`
`MOE
`
`MOR
`
`Perpendicular
`MOR
`
`MOE
`
`Falling
`ballimpact
`
`IB
`
`Rail
`shear
`
`(10_ psi)
`(psi)
`(psi)
`(10_ psi)
`(in.)
`5,550
`319
`3,903
`59
`1
`444
`2
`414
`5,436
`310
`3,734
`42
`362
`3
`424
`4,762
`4,191
`36
`a ANSI/AHA A135.6 requirements: Minimum MOR (parallel) = 1,800 psi; minimum impact = 9 inches.
`
`.........(psi).........
`1,689
`77
`41
`1,735
`55
`1,985
`
`Plate
`shear
`
`(I(Ppsi)
`218
`176
`256
`
`TABLE 4.- Performance characteristics
`
`(4 by 8 ft.) attached to 8- by 12-ft. wood frames, after 21 days of water-spraying
`of paper_verlaid
`OSB panels
`the overlaid surface according to APA test methods
`(P-2, P-11, P-12).a
`
`on
`
`Panel
`I.D. b
`
`1-1
`1-2
`1-3
`Average
`
`2-1
`2-2
`2-3
`Average
`
`3-1
`3-2
`3-3
`Average
`
`Thickness
`swelling of
`drip edge
`(%)
`24.1
`25.9
`27.1
`25.7
`
`22.0
`20.3
`25.9
`22.7
`
`23.9
`31.6
`24.4
`26.6
`
`Edge gap-
`depth c
`(in.)
`F> .125
`F> .125
`F> .125
`F > .125
`
`M <.125
`F>.125
`F >. 125
`F > .125
`
`F< .125
`M > .125
`M< .125
`F> .125
`
`Telegraphing
`(%)
`60
`60
`60
`60
`
`70
`70
`65
`68
`
`50
`55
`50
`52
`
`aOverlaid surfaces and drip edges were primed with oil-based primer and then painted with flat exterior latex paint prior to testing.
`bThe first number designates
`the mill that preduced the OSB, the second number is the panel number.
`The lettersM and F designateMany and Few gaps.Example:M <.125 indicatesmany checkslessthan 0.125inchdeep.
`
`FOREST
`
`PRODUCTS
`
`JOURNAL
`
`VoL40, No. 4
`
`Top
`.....................
`0.017
`0.041
`0.030
`0.029
`
`Additional buckling
`Bottom
`Middle
`(in.) .................................
`0.020
`0.022
`0.080
`0.023
`0.034
`0.027
`0.045
`0.024
`
`Frame expansion
`Width
`Length
`(%) ...........
`0.00
`0.14
`0.13
`0.09
`
`0.11
`0.13
`0.22
`0.16
`
`0.017
`0.026
`0.032
`0.025
`
`0.023
`0.026
`0.041
`0.030
`
`0.007
`0.017
`0.009
`O.011
`
`0.020
`0.037
`0.023
`0.027
`
`0.020
`0.020
`0.014
`0.018
`
`0.020
`0.044
`0.022
`0.029
`
`0.17
`0.31
`0.17
`0.22
`
`0.10
`0.08
`0.13
`0.11
`
`0.13
`0.13
`0.06
`0.11
`
`0.33
`0.06
`0.19
`0.19
`
`59
`
`Louisiana-Pacific Corporation, Exhibit 1021
`IPR of U.S. Pat. No. 8,474,197
`Page 5
`
`

`

`cannot be avoided for every panel. Drip-edge
`apparently
`checking was evident
`in all panels (see example in Fig. 1).
`In six of the panels, edge checking was deeper and wider
`than is allowable
`(3). The average
`expansion,
`in both di-
`rections, of the restrained
`panels
`in the frames was less
`than 0.20 percent of that
`required (3). The average buck-
`ling between supports was approxima_ly
`0.029 inch, which
`is within the permissible
`requirements
`(3). The average
`surface telegraphing was visually estimated at between 50
`and 70 percent. These amounts of telegraphing
`give the
`panels an unattractive and objectionable appearance (Fig. 2).
`Experiment 3
`
`for small overlaid panels (10.5 in. wide by 48
`Results
`in. long) that were framed as lap siding with a 1-inch over-
`lap and exposed to 21 days of water-spraying
`are shown in
`Table 5. In this group, average
`thickness
`swelling of the
`drip edge varied between
`11.7 percent
`and 21.1 percent.
`Checking
`of the drip edge was evident
`in all sections.
`In
`each section tested,
`there were several checks in the drip
`edge that were deeper and wider
`than allowed (3). The
`average
`surface
`telegraphing
`in es,ch section was visual-
`ly estimated
`at between 40 and 65 percent. The overlaid
`
`or cracks dur-
`
`surface did not develop any delaminations
`ing exposure.
`Results
`for the small overlaid panels that were 22
`long, framed with drip edges
`inches wide by 48 inches
`not overlapping,
`primed and coated "with four combina-
`tions of primers, paints, and resin and[ exposed to 21 days
`of water-spraying
`are shown in Table 6. In this group,
`average
`thickness
`swelling of the drip edge varied be-
`tween 14 and 21 percent. The thickness
`swelling of drip
`edges oriented perpendicular
`to face flakes was 2.5 per-
`cent
`larger. Checking
`of the drip edge was evident
`in all
`sections.In 18out of 24 tested sections,the checksthat
`developed in the drip edge were deeper
`and wider
`than
`allowed (3). The average surface telegraphing
`in each sec-
`
`tion was visually estimated
`
`at between 35 and 50 percent.
`
`Figure 1. -- An example of excessivedrip-edge checking in
`panels and sectionssealed withoil-basedpaint,enamel, or
`epoxyprimerand overcoaters,
`
`Figure 2. -- An example of telegraphingthat developedon
`alltestedoverlaidpanelsandsectionsafter 21 daysofwater-
`spraying.
`
`TABLE 5. -- Performance
`
`characteristics
`
`of paper-overlaid OSB sections (10.5 in. wide by 48 in. long) after 21 days of water-spraying
`to modified APA tests (P-2, P-11, P-12). a
`
`according
`
`Surfacefinish
`
`Enamel paint
`
`Oil paint
`
`Glossy exterior
`
`latex
`
`Epoxy paint
`
`Epoxy resin
`
`OSB
`mill
`
`1
`2
`3
`
`1
`2
`3
`
`1
`2
`3
`
`1
`2
`3
`
`Average
`
`Average
`
`Average
`
`Average
`
`1
`2
`3
`Average
`
`Thicknessswelling
`ofdripedgeb
`..........................
`19.0
`21.4
`22.8
`21.1
`
`Water
`absorption
`(%) ..........................
`19.6
`22.5
`31.8
`24.7
`
`15.7
`14.1
`20.8
`16.9
`
`13.9
`18.0
`13.2
`15.0
`
`13.7
`15.6
`5.6
`11.7
`
`22.8
`21.8
`16.6
`20.4
`
`23.3
`21.7
`26.2
`23.7
`
`13.6
`18.5
`16.9
`16.4
`
`16.2
`18.8
`13.2
`16.0
`
`20.6
`25.7
`21.6
`22.6
`
`Gap
`depth
`(in.)
`M>.125
`M>.250
`M> .200
`
`M> .125
`M>.250
`M>.225
`
`M > .165
`M>.200
`M>.150
`
`M>.125
`M>.300
`M> .200
`
`M> .125
`M> .200
`M>.200
`
`Telegraphing
`(%)
`38
`45
`55
`46
`
`45
`45
`45
`45
`
`60
`65
`62
`63
`
`32
`42
`35
`37
`
`45
`45
`28
`39
`
`a Paper-overlaid surfaces were primed with oil-based primer while edges were primed with epoxy paint. Afterward,
`painted with the finish indicated. Each wLlue represents
`the average of two sections.
`the direction
`bThe drip edge represents
`perpendicular
`to the panel
`length.
`
`surfaces and edges of each group were
`
`60
`
`APRIL1990
`
`Louisiana-Pacific Corporation, Exhibit 1021
`IPR of U.S. Pat. No. 8,474,197
`Page 6
`
`

`

`TABLE 6. --Performance
`
`characteristics
`
`(22 in. wide by 48 in. long) after 21 days of water-spraying according
`of paper-overlaid OSB specimens
`to APA tests (P-2, P-11, P-12).a
`
`Face
`
`Enamel
`
`Surface finish
`
`Edge
`
`Epoxypaint
`+ enamel
`
`Oil
`
`Epoxy paint
`+ oil paint
`
`Enamel
`
`Epoxy resin
`+ enamel
`
`Oil
`
`Epoxy resin
`+ oilpaint
`
`Section
`I.D. b
`
`__
`
`1-Pa
`2-Pa
`3-Pa
`
`1-Pe
`2-Pe
`3-Pe
`
`1-Pa
`2-Pa
`3-Pa
`
`1-Pe
`2-Pe
`3-Pe
`
`1-Pa
`2-Pa
`3-Pa
`
`1-Pe
`2-Pe
`3-Pe
`
`1-Pa
`2-Pe
`3-Pa
`
`1-Pe
`2-Pe
`3-Pe
`
`swelling
`Thickness
`of drip edge
`(%)
`20.2
`17.4
`11.2
`16.2
`21.3
`21.4
`9.7
`Average 17.5
`
`Average
`
`13.4
`15.7
`17.1
`Average 15.4
`16.9
`23.7
`11.7
`17.4
`
`Average
`
`20.0
`21.8
`16.2
`19,3
`16.7
`23.3
`23.0
`21.0
`
`Average
`
`Average
`
`16.2
`14.1
`11.8
`Average 14.0
`18.4
`18.3
`20.4
`19.0
`
`Average
`
`Gap
`depth
`(in.)
`F< .125
`F>.125
`F<.125
`
`M>.125
`M>.125
`M>.125
`
`F=.125
`M< .125
`M=.125
`
`M> .125
`M > .125
`F >. 125
`
`F > .125
`M>.125
`F<.125
`
`M>.125
`M>.125
`M>.125
`
`F < .125
`M<.125
`F=.125
`
`M > .125
`M>.125
`M>. 125
`
`Telegraphing
`(%)
`40
`40
`45
`42
`35
`50
`35
`40
`
`40
`40
`45
`42
`30
`35
`50
`38
`
`30
`50
`45
`42
`25
`50
`50
`42
`
`30
`40
`30
`33
`30
`50
`40
`40
`
`a Paper-overlaid surfaces were primed with oil-based ]primer and then painted as indicated. Drip edges were primed with either epoxy paint or epoxy resin
`and then painted as indicated.
`bPa and Pe designate
`drip edge directions parallel and perpendicular
`
`to the panel
`
`length.
`
`TABLE7.- PerformancecharacteristicsofOSBpanelswithfactory-primed
`resin-impregnated
`pape