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Gridcore® Panels User's Guide Instructions for the care and handling of Gridcore panels.  |
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Index
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Introduction to Gridcore® Products Gluing Gridcore® Products |
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User's Guide
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Introduction to Gridcore® Products Welcome to the world of Gridcore® panel products. The Gridcore® User's Guide is intended to provide helpful information to manufacturers and artisans working with this remarkable new material. Gridcore® products can inspire innovative designs, new products and new applications. Our goal is to help you realize your fabrication objectives as quickly and economically as possible.
Working with Gridcore® panels does not require significant capital investment in specialized equipment. Basic wood working tools coupled with proper blades, bits and fasteners yield excellent professional results.
This User's Guide is organized to cover the basics of cutting, fastening, edging, joining, curving and surfacing. Each section provides an overview, description, tool tips, pictures and illustrations.
Please call, write, fax or E-mail them to the Marketing Department (gridcore@worldnet.att.net) GSI is the exclusive licensee of USDA patents in a wide range of commercial applications including exhibits and displays, stage sets, furniture and cabinetry, toys and games,
construction products, building systems, and transportation applications. GSI pays the USDA a royalty for this license and through collaborative research work, GSI and the USDA have formed a public/private partnership which has substantial benefits to the American people.
• Superior Strength-to-Weight Performance C. Characteristics Gridcore® standard 3/4" nominal panels have the approximate bending strength of low density particleboard, but at less than half its weight.
Size 4' x 10' x 3/4" (Nominal) 43 D. Environmental Features Gsi uses no toxic resins or binders in the gridcore® manufacturing process. Gridcore® panels can be made from100% post-consumer waste and agricultural fibers. Gridcore® products can be manufactured with little impact to the environment. E. Recommended Applications
Gridcore® panels are an ideal core material for art boards, graphic signage, point of purchase displays, trade show exhibits, toys and games, furniture and cabinetry and interior design applications. They can be painted, laminated, edged and veneered. They also can be curved to custom radii and compound shapes.
With the addition of additives and coatings for increased water resistant and fire retardation, Gridcore® panel products will eventually be used in a number of building, construction and transportation applications. These advanced product features are currently in development.
However, untreated Gridcore® standard panels are NOT recommended for external applications where exposure to moisture will degrade the material. Gridcore® panels are not currently rated or certified for structural applications such as housing or construction. Cutting Gridcore® Products
A. Overview
Before revving up your power tools, take a moment to get the feel of the material. You will immediately notice that Gridcore® panels are both rigid and light. The panels are remarkably uniform in consistency and quality. As a result, they behave well when being cut. Airborne materials are easier to clean up and less irritating than particleboard or MDF, and you can say "good-bye" to chips and splinters.
Success in getting clean cuts with Gridcore® panels depends on the sharpness of your tools. Standard blades will cut Gridcore® panels, but for superior results we recommend using sharp High ATB (40 degree) blades.
To clean up your edges after a cut, use a fine sandpaper on a sanding block at an angle to the face. A "flap sander" mounted on a drill press also works well to clean up the edge cells, but simply blowing out the edge fuzz with compressed air will yield satisfying results. B. Hand Saws & Knives
A sharp, sturdy utility knife works well with the material, particularly when performing detailed work with Gridcore® sub panels or with Gridboard® flat sheets. There are specialty utility knives which cut very well, particularly when the blade is set at a slight angle to the material.
Hand cutting is best accomplished with a Japanese pull saw type of tool. These saws are razor sharp, with teeth raked forward to cut in the pull direction, and do a superior job cutting Gridcore® panels. (Rip saws tend to fray the edges and are therefore not recommended for anything but fast, rough cuts.) C. Circular Saws
With wood, the stiffness of the fibers and their embodiment with lignin or resin allows a less than sharp blade to shear the fibers and achieve a decent edge. In contrast, Gridcore® panel fibers are mechanically locked together and will pull if cut with a dull or low angle blade. The more the blade's approach to the material approximates a slicing action, the cleaner the cut.
Because Gridcore® panels have a glue line in the center, residual adhesive tends to build
up on the saw face. This should be cleaned regularly to prevent friction and heat. Plywood steel blades (60 teeth) cut very rapidly but do not yield as clean a cut as carbide tipped blades (24 teeth) moving at slightly slower speeds through the material. Lubricants will also improve overall performance.
Again, carbide tipped blades with a high ATB give the cleanest cuts, with little fray on the exit side. The lower the kerf, the better. Gridcore® sub panels are best cut with the ribs in contact with the table top. You may find that there is some ragging on the trail edge of the internal cell material, which can be cleaned up with fine sandpaper. If your goal is to reveal the hexagonal ribs, you may want to flip the panel over to achieve cleaner rib appearance.
A professional panel saw equipped with an 8" 40-tooth carbide-tipped blade cuts Gridcore® standard panels very well.
Clean curvilinear cuts can be made on Gridcore® panels using a band saw. Several users have utilized 20" wheels top and bottom, with a 7 TPI by 1/2" deep blade. The material cuts quickly, requiring close attention to the line of the cut as the material is fed into the saw. Knocking down the ridge with fine sandpaper is recommended.
A number of band saw blades have been tried, but standard narrow kerf blades seem to work best. Bi-metal blades, while making a cleaner exit cut, tend to have an irregular surface along the edge. Knife blades and scalloped butcher blades leave a very clean edge, but tend to overheat unless care is taken to move the saw slowly through the material. E. Jig Saw
In general, hand-held jig saws work well with Gridcore® products. A smoother cut can be obtained with a universal medium blade (10 teeth per inch). Both require cleanup of the exit surface. A leather cutting smooth blade (razor knife) makes a very smooth cut. Again, the blade can overheat and the surface of the cut may develop a burnished glaze if the cut is done too fast.
Variable speed scroll saws cut Gridcore® panels well. Blades with 12 teeth per inch and .016" thick by 0.43" wide have worked well in some applications.
SANDING Gridcore® products
All Gridcore® standard panels are For best results in cleaning up after cutting Gridcore® panels, use fine grades of sandpaper (200-400 grit). A light touch with a hand block is generally all that is needed.
An orbital sander with 80-grit works well to remove excess fiber from the edges, but beware of oversanding. If you raise some fuzz, it won't go away by pressing harder. Use a finer grit and less pressure for best results. Belt and disc sanders remove fiber very quickly and are recommended only for rougher jobs.
To clean up the edges, mount a "soft sander" on your drill press and run the material across the flexible tool to remove fuzz and fiber. Gluing Gridcore® Products
Most adhesives work extremely well with Gridcore® panels. The material will bond securely to itself as well as to other wood, fiber and plastic materials. Rib alignment will increase strength when gluing up Gridcore® panels. The larger the bonding surface area, the stronger the bond will be.
In many applications, contact cement, epoxy and urethane adhesives have enough initial tack to hold joints together while curing. Other adhesives may require joints to be clamped while the material sets to assure a permanent bond. A. PVAs
Carpenter's glue and any white glue work well with Gridcore® products. In fact, PVA's are used to bond the two sub panels together in the standard 3/4" product. PVA's work well when fastening wood to Gridcore® panels, for example to insert wood edges.
For faster set up times use modified PVAs for fast cure.
(NOTE: If you are veneering or laminating to Gridcore® panels in a hot press, be sure to use a different core adhesive, as the water-based PVAs will steam and delaminate the panels. GSI can supply panels with heat resistant adhesives upon request.) B. Contact cement
Contact cements work well, particularly when constructing mitered corners, box beams, or when applying veneers and laminates in a cold press.
Make sure to remove all frayed or fuzzed fibers from the panel surfaces prior to gluing. Apply contact cement to both surfaces according to manufacturer's instructions. Clean up the edges with a block of fine sandpaper.
Most contact cements will work well. Water-based cements can be slightly more difficult to use due to their slow set up times. Fastening Gridcore® products
Withdrawal resistance is a common measure of the holding power of particular fasteners for a given material. Resistance normally depends upon the density of the material, the diameter of the fastener, and the depth of its penetration.
Because Gridcore® panels have a hollow, honeycomb structure, attention must be paid to appropriate fastening systems. Nails are not recommended in most applications, yielding a resistance of only about 29 pounds for 8d and larger fasteners.
However, there are a number of fasteners that work well with Gridcore® panel products. A. Screws
Screws hold well in Gridcore® panels, particularly when driven through both faces of the panel. Coarse drywall screws and wide profile plastic screws can achieve pull values of over 200 pounds. Using plastic toggle inserts in combination with screws will further increase holding power and provide face protection to reduce denting. "Potting" or filling the cells to be fastened with epoxy will greatly increase screw holding power.
Fastening into the honeycomb edge with 1.5" screws can produce withdrawal resistance of 40 to 60 pounds. Filling the Gridcore® cells with epoxy will improve pull strength. B. Pop Rivets
While drywall and other screws will work with Gridcore® panel rivets work even better. They are cost effective and yield very satisfying results in many Gridcore® product applications.
3/16" peel (pop) rivets are recommended. They can be placed blind into the Gridcore® face material, without regard for rib alignment. A pilot hole is required. Both manual and pneumatic rivet guns are available. Pre-threaded rivets which have screw tapping capabilities are also available.
(NOTE: The snapped off steel mandrels end up inside the honeycomb cells and may rattle around inside. This can be reduced by putting a drop of glue on the head of the rivet before inserting into the panel.) C. Staples
Staples can fasten Gridcore® products. Keep the air pressure on the staple gun low so that the fastener does not blow through the face of the panel. 2" long x 7/16" wide staples deliver a withdrawal resistance of over 100 pounds. Finishing staples also work well. Pneumatic nails are not recommended for most applications.
D. Tapes
In general, tapes do not adhere exceptionally well to untreated Gridcore® panels because of the fibrous nature of the material. However, once Gridcore® panels have been sealed, the holding power of a number of tapes is quite good, making it an acceptable fastening solution for temporary assemblies. Duct tape has good holding power and can even be used to apply a fast edge to the material.
E. Bolts
Bolts are another effective means of fastening Gridcore® panels. Wide, flat-head bolts which thread into each other are a fastening solution often used in honeycomb construction. The use of washers will increase their holding power and reduce face deformation of the panels.
Flathead stove bolts are also effective. Countersinking the head of the bolt does not seem to effect the fastener's performance, and does sit flatter and have a cleaner appearance. Bolting within 3/4" inches from the perimeter is not recommended because it tends to crush the edge. F. Insert fasteners
There are many types of insert fasteners which have been designed for honeycomb applications. Filling a Gridcore® cell with epoxy compound in conjunction with an insert fastener can yield exceptional holding power.
G. RTA Fasteners
A wide range of fasteners are available from companies such as Hettich and Haeffele, which can achieve blind fastening, particularly for making 90 degree angles. We recommend filling the panel cells with reinforced epoxy, or using wood inserts or dowels in combination with these fasteners, for more structural applications.
H. Biscuit Joinery
Plastic or wood biscuits can work well, particularly for joining panels or wall assemblies edge-to-edge. We recommended using these fasteners in conjunction with wood inserts dadoed into the edge of the Gridcore® panel. Use plastic friction biscuits for knock-down assemblies, and wood biscuits with PVA adhesives for permanent installations.
Edging Gridcore® products A. Raw
While there are many ways to edge Gridcore® panels, there is a certain aesthetic to revealing the inner core. If desired, you can seal the honeycomb edges with clear acrylic or polyurethane coatings to provide some protection from moisture absorption. Try humidity crosslinking polyurethane based adhesives.
B. Gridboard
GSI manufactures Gridboard® flat sheets, a thin sheet stock material which can be cut in strips and used as a natural edge-banding material. It can be hand applied or run through a commercial edge-banding machine in 10-foot lengths. The fiber material bonds to itself with most adhesives. Sanding is required for clean-up.
C. Commercial Edge-banding
Gridcore® panels can be successfully run through commercial edge-banding equipment, but some adjustments are required for satisfactory results. Edge-banders are set up to pull much heavier sheet stock down the line. As a result, the pinch rollers tend to dent or crush Gridcore® panels. Reducing the pressure on the pinch rollers and slowing down the line speed will improve performance.
Unlike particleboard or plywood, Gridcore® panels have a honeycomb interior. As a result, the edge material must span from rib to rib. Thin material such as 1mm veneer or PVC tends to telegraph this rib pattern. We recommend using thicker edge-banding stock (for example 2mm or 3mm PVC) for best results.
Standard hot melt glues will hold both wood and plastic edging. For best results, use a reverse roll coat running against the feed. This will increase the glue bond significantly. Laminating the part or component first, then running it through the bander will also improve overall results. D. Wood Inserts
Mortised wood inserts are another excellent way to edge Gridcore® panels. Dado out the Gridcore® edge material, leaving the top and bottom faces intact. Insert the wood molding using a PVA adhesive, then trim and sand to specification. This edge will provide increased crush strength to the panel, as well as provide hard points for hinges, biscuits and RTA fasteners.
E. Edge Fillers
Several varieties of filling compounds have been used to seal Gridcore® edges. Quick dry fillers and epoxy-based syntactic foams work best. (Drywall joint compound is too thin to stay in the ribs and creates an uneven surface.) After applying filler, sand the edge with 80-grit paper, or trim the edges on your table saw for clean results.
Syntactic foams are used widely in aerospace and marine applications for filling honeycomb materials and can be adopted when fabricating with Gridcore® panels. The foams can be formulated to harden either rapidly or slowly, to accept screws or not, and to yield exceptional crush strengths. They can also be pigmented to match other finishes.
The advantage of using filler edge materials is that they will go around any shape or form. The disadvantage is that in most cases they require manual application. G. T-molding
It is possible to use plastic and metal T-molding with Gridcore® products. Using an epoxy adhesive to assure a secure hold is advised. Molding with teeth on the inserted edge provides more permanent bonding. Plastic and aluminum molding has been successfully used in a number of applications.
H. Picture framing
A number of fabricators have created a box construction with Gridcore® products by building a frame around the material. This can be accomplished either by dadoing out the edges and inserting the picture frame, or running the wood framing around the periphery of the Gridcore® panel, then laminating or veneering the entire assembly together.
I. Extrusions
There are a wide variety of plastic and metal extrusions on the market that work well with Gridcore® panel products. They are easy to apply, protect the edge of the honeycomb and can be purchased in many colors and profiles. Some of these extrusions, for example "H" channel, also provide panel-to-panel fastening. Extrusions can be secured to Gridcore® panels using either glue or pop rivets.
Joining Gridcore® products
Building elegant, structural, three dimensional assemblies with Gridcore® panels is very easy. However, the honeycomb nature of the material does present challenges. Here are some suggestions.
A. Butt Joint
While it is possible to simply glue Gridcore® pieces together at a 90 degree angle, this type of joint can be strengthened significantly by inserting hard edges and using appropriate fasteners or hinges in combination with adhesives or pop rivets.
"L" shaped angle aluminum or "H" channel extrusions can be used on either side of the joint to support the structure. It is also possible to use wooden dowels glued into Gridcore® panels to serve as hard points for screws and other fasteners. B. Miter Joint
Mitered joints are an excellent assembly technique. Follow standard safety procedures when setting up your 45 degree saw cut. Make sure to clean the surface areas of all fuzz and fiber prior to applying glue.
Contact cement is a good choice for this joint because it does not require clamping. Apply two coats to each surface, letting them dry for the period recommended by the manufacturer, then join the pieces to form a strong bond. Clean up edges with fine sandpaper. Epoxy or urethane adhesives can be used to make an even stronger miter joint, but it is also more difficult to clean up after the process, and may require clamping. C. Rabbet Joint
Rabbet joints can also be accomplished with Gridcore® panels. A dado blade installed on your table saw can be used to remove one face and the adjoining hexagonal ribs, leaving a notch. Glue the next panel directly into the notch.
D. Wall or "flat" assembly
A wonderful feature of Gridcore® products is their ability to make light-weight vertical walls or "flats" for theatrical, exhibit and interior design applications. One set builder has constructed an 8'x10' rectilinear flat using only peripheral 1"x3" pine framing. The final assembly can be easily moved by two people. This construction technique reduces time and materials, provides a smooth, grainless surface, and has a fastener-free surface.
1.24" drywall screws fastened through the framing and into the back face of the Gridcore® panel have more than enough holding power for most applications. Peripheral framing is all that is required, but framing along the adjoining seems is suggested for panel-to-panel alignment and gap reduction. Wall units can be fastened together using wood or plastic biscuits, dowels or cam locks.
E. Seam Treatments
When more than one Gridcore® panel is used to make an assembly and a seamless look is required, the joint can be treated in several ways. A layer of material such as muslin, cheesecloth or kraft paper can be glued on the front of the panel over the seam prior to painting or surfacing. Muslin seems to work best since the material smoothes out well. The edges fray slightly, eliminating the harsh line of the seam.
Putty can be used to fill the seams. This method treats Gridcore® panels similarly to drywall panels in home construction. Curving Gridcore® Products
A. Bending Over Form
The most common way to curve Gridcore® panels is to create a rigid form in the shape of the desired radius. We have used everything from hardboard bent over a wood frame to paper tubes and drums for tighter radii. If the desired radius is very tight, lightly misting the sub panels with water on both sides prior to curving will make it more pliable.
Apply PVA glue to the honeycomb ribs of the first sub panel. Place the next sub panel (or Gridboard® flat sheet if thinner curves are required) face down onto the first sub panel. Bend it over the frame, clamp it securely and let it dry. When the curve is removed from the frame, it will maintain its shape with very little spring-back.
Wrapping the curve using plastic non-stick caution tape or plastic wrap works well as a uniform clamping system. B. Positive/Negative Forms
For tight curves and compound shapes, a top and bottom form can be created similar to those used to make plywood seat backs and bottoms. Moistening the panel prior to insertion into the mold will increase its bendability. Heat is not required for this process.
C. Vacuum Bagging
For multiple parts and industrial quantity manufacturing, vacuum bagging over a form can be an effective way to curve a Gridcore® panel. Again, heat is not required or recommended.
D. Kerfing
It is also possible to create temporary or permanent curves in Gridcore® panels by using a kerfing method. Simply make a series of cuts across the panel, from edge to edge, through the face and ribs, leaving the bottom face of the panel intact. The radius of the curve is determined by the spacing of the kerf cuts and the width of the cuts themselves. For a permanent curve, simply apply glue into cuts and bend to form. Secure the assembly until the glue has dried.
Surfacing Gridcore® Products
A. Sealing
Priming or sealing Gridcore® panels contributes to the dimensional stability of the panels, and can improve their final appearance. Dry wall primer is a cost-effective product that works very well with Gridcore® panels. They can be sprayed, rolled or brush applied.
We encourage the use of low VOC, water-based paints. Water based acrylics and latex primers as well as mineral spirit based polyurethanes yield fine, smooth surface finishes. The first coat will often raise the honeycomb pattern of the fibers, requiring a second base coat or a thicker finish coat. Fine sanding between coats yields best results.
We have found that ultra-violet light (UV) cured epoxy coatings provide exceptional finishes B. Painting
Gridcore® panels can be painted with virtually all commercially available products. Again, we encourage water-based low VOC paints. The fiber orientation of the ribs is different than those spanning the hex pattern, which causes uneven paint absorption. For best results, use a primer prior to the finish coat.
Paint on Gridcore® panels will often dry to the touch faster than on plywood or particleboard. Make sure to coat both sides to avoid warping. Once the paint dries, it yields a very hard Brushes, sprayguns and rollers all work well on the material. Thicker, less diluted solutions tend to hide the hex pattern better than thinner applications. C. Texturing
Exciting textures can be applied to Gridcore® products for theatrical, interior design and exhibit applications. To create a stucco or concrete appearance, flexible glue and potters clay (one part clay, three parts glue) can be applied with a putty knife or trowel. Mixtures of sawdust and paint or glue can also be used to texture Gridcore® panels. Once dried, paint can be applied.
Some customers have found that Gridcore® panels hold plaster extremely well. Textured paints also deliver professional results. D. Flame Proofing
Many theatrical, exhibit and interior design applications require non-combustible materials. A number of fire retardent coatings are available which are formulated for cellulose and synthetic textile fibers. Many of these are compatible with Gridcore® products. Retardent can be mixed into the primer and/or into the final paint coat. Most solutions will not effect the color or appearance of the finished panel.
E. Laminating
As with all panel products, it is important to balance the panel, particularly when applying laminates or veneers. Using a phenolic-impregnated backer material will accomplish this while saving time and money. For cold press laminates, use PVA adhesives.
If you are applying laminates without a press, we recommend using contact cement. F. Veneering
Wood veneers can be effectively applied to Gridcore® panels. Make sure to achieve a balanced component by covering both sides with a similar veneer or appropriate phenolic paper backer.
The maximum pressure Gridcore® panels can safely withstand in a press is about 50 PSI. If using a hot press, epoxy or modified PVA adhesives must be used to bond the panels. Please contact GSI and ask about custom orders of epoxy or modified PVA bonded panels in order to prevent delamination during hot pressing. G. Fiberglassing
Gridcore® panels bond very well to fiberglass and resin. For best results, pour the resin evenly over the surface and brush in or squeegee down the cloth against the surface. Let dry and apply finish coats according to manufacturer's recommendations. Make sure to work in a well ventilated area and properly dispose of all waste materials. Gridcore® products as a Graphic Substrate
Gridcore® panels provide an exceptional substrate for painters and graphic artists. Unlike canvas, it does not have to be stretched or framed. It will not warp as readily as hardboard or foam panels. It also contains no toxic binders and will not off gas.
Gridcore® panels are a perfect medium for mounting photography, interior signage and other graphics. They can also be silk screened on to directly. Solid edges can be accomplished using commercial edge-banding equipment, solid wood profiles or Gridboard® flat sheets.
Latex gesso works well as a primer/sealer for acrylic and oil painting. We recommend sealing both sides of the panel to assure balance and reduce warping. |
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