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A substrate is the material to which a veneer is bonded. With careful preparation and adhesive selection, almost any smooth surface can be veneered. Let's begin this article with one of the most common substrate questions.
"What size should I make my substrate in relation to the veneer?"
When building a veneered panel from scratch, try to avoid having any veneer overhang by simply cutting the substrate larger than the required final panel size. Cut the substrate 1" larger than the required size of the finished panel on all 4 sides. Then lay up the veneer .5" larger than the required size of the finished panel on all sides. Then center the veneer on the substrate after the veneer glue is applied.
After the panel cures, trim the panel to size on the table saw with a plywood crosscutting blade. If the veneer isn't perfectly aligned on the substrate, cut a starting straight edge with a band saw or jig saw and then clean up edges on the table saw.
| Example: |
| Step 1 |
Required Panel Size |
22" x 46" |
| Step 2 |
Substrate Size
|
24" x 48" |
| Step 3 |
Veneer Size |
23" x 47" |
| Step 4 |
Finished Panel Size |
22" x 46" |
| Tips: Trimming Finished Panels |
- Be sure to allow the panel to fully cure before trimming to final size. If the glue has not cured, the veneer may splinter heavily at the cut.
- To minimize tear out on the face side, set the blade height a little higher than normal and cut the panel with the face side up.
| Here are some common substrates used with wood veneer. |
MDF/MDO (medium density fiberboard/overlay)
MDF
is used frequently used on the finest veneered furniture pieces.
Its uniformity and stability make it an excellent substrate for veneer
work. When
using MDF or MDO as a substrate, thoroughly sand the surface
with 80 grit sandpaper to provide a better grip for the glue. To test the substrate, place a drop of water on the surface. If the water keeps a bead shape after ten seconds, it needs more sanding. However, if the water flattens out and is absorbed by the substrate, then it is ready for application of veneer glue.
Plywood
Plywood has the advantage of being lighter, more sag resistant, and it grips fasteners better. It generally does not require any kind of surface preparation prior to applying the glue. There is one caveat of plywood. Shoddy plywood is everywhere these days. The face veneer on these sheets will often peel off with little effort. Check your plywood before veneering it to make sure the veneer face is not loose or poorly bonded. If the veneer peels off easily, it is pointless to apply a nicer veneer over it.
Particle
Board
Particle board is also a good veneering substrate but not as
fine as MDF. When
using particle board as a substrate, lightly sand the surface
with 80 grit sandpaper to provide a better grip for the glue. To test the substrate, place a drop of water on the surface. If the water keeps a bead shape after ten seconds, it needs more sanding. However, if the water flattens out and starts to be absorbed by the substrate, then it is ready for application of veneer glue.
Hardwood/Softwood Lumber
The problem with solid wood is that it will expand and contract with seasonal humidity changes in the house. When a solid wood substrate is needed, you'll find that quartersawn or rift cut lumber is ideal since it has less seasonal movement than flat cut lumber. You'll also want to use a hard-setting PPR adhesive like Ultra-Cat. You'll need a vacuum press to clamp the veneer while the glue dries (4 to 6 hours).
Metal
Metal substrates are not porous and therefor require a slightly different process for veneering. Start by adhering a backer grade veneer to the surface using polyurethane glue. Metal epoxy can also be used but it is expensive and messy. When this has cured, you can then apply a face grade veneer to the backer veneer using veneer glue. If the project will be subjected to high heat and humidity, you'll want to use a powdered urea resin glue such as Ultra-Cat.
Masonite/HDF/Hardboard
The glues used to make hardboard sheets are sometimes thin and weak. This makes it difficult to get a durable bond between the top surface of the substrate and the veneer. I've been able to peel a veneer off a hardboard substrate and in doing so, I also removed the top layer of the hardboard material. Regardless, some have reported success using hardboard that has been thoroughly scuff sanded with 60 grit. If you apply veneer to this kind of material, it is very possible that the edges will eventually start to lift so its important to capture or frame the edges of the panel with hardwood to prevent any delamination issues.
Glass
The truth is that there are no adhesives designed for this type of application and finding one that works consistently is not easy. Instead of gluing the veneer onto a substrate like this, consider purchasing a paper-backed veneer with a pressure sensitive adhesive (PSA) backing. With this type of veneer backing, you simply peel the wax paper sheet from back of the veneer and stick it to any non-porous surface. It sounds cheap but it sticks surprisingly well.
Plexiglass or Acrylic
This is a another tricky substrate but veneer can be bonded to plexiglass with epoxy as long as the substrate will be supported and not allowed to bend. The key is to scuff sand the substrate material with 100 grit sand paper until it is thoroughly opaque. The tiny grooves created by sanding will give the epoxy a place to "bite".
Drywall
I do not recommend application of paperbacked veneer directly to drywall. Instead, cover the drywall with ½" MDF using construction adhesive. Then a paperbacked veneer can be applied to the MDF. Contact cement and PSA are the most commonly used adhesives options.
The PSA backing is an available option on all of the paperbacked veneers at VeneerSupplies.com and is applied to the veneer at the factory. Simply peel off the protective backing and stick it to the project. It works surprisingly well and the bond is as strong as contact cement. To get the best possible bond, apply a coat of shellac (available at most hardware stores) to the drywall before applying the veneer.
 Regardless of the adhesive option you chose, you will need to "set" the bond to the drywall with a scraper tool. Begin at the center of the veneer and work toward the edges in the sequence shown below. This method will prevent bubbles in the veneer and create an excellent bond.
Start in the center and drag the scraper tool in the direction of the arrows. Be sure to pass the tool over each inch of the veneer to get the best possible bond.
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