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Wood Veneers: Flattening and Cutting Techniques From "Wood Works" episode WWK-609

A vacuum press is used to create wood-veneer panels. Pressure of 1500 pounds per square foot bonds the thin veneer sheets to both sides of the MDF or plywood substrate.

In this episode of Wood Works, the topic is wood veneers. In this segment, host David Marks offers tips on flattening and prepping burl veneer.

Veneer-Storage Tip: Store valuable veneers on a flat shelf sandwiched between sheets of MDF or plywood and taped securely. Keep them in a cool, dry place to minimize warping or damage.

Materials used in this segment:

Vacuum press
Jointer
Band saw
Hand-held router
Water
Glycerine
Alcohol
Slow-setting plastic-resin glue
Mixing container
Fiberglass window-screen
Newsprint paper
Carpenter's tape
Straight-edge
Paintbrushes
Clamps
Safety glasses or goggles

Safety Alert: Always wear safety goggles or safety glasses, and follow proper safety precautions, when working with wood, power-tools, saws, drills, routers, etc.

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Figure A

Flattening Veneers


Veneers -- especially those from burls -- have a tendency to buckle and warp over time (figure A). Here's a technique for flattening veneers while enhancing their strength and flexibility:

Create a flattening solution using the following formula (figure B):

• Four parts water;
  
• Two parts glycerine;
  
• One part alcohol and
  
• Two parts plastic-resin glue.

• Mix thoroughly.

• Use a paintbrush to apply the solution to both sides of the veneer until they are saturated (figure C).

  Figure B

  Figure C

  
  

  
  

• Then, to dry the sheets flat, place the sheets within a "sandwich" made using wood cauls, a few sheets of newsprint paper to absorb moisture, and fiberglass window-screen. Lay the veneer flat (figure D), adding a piece of fiberglass window-screen on both sides of each veneer. The screen prevents the veneers from sticking to the newsprint as they dry.

• Top the sandwich with a second wood caul (figure E).

  Figure D

  Figure E

  
  

  
  

• Use even clamping pressure (figure F) to squeeze out the excess solution and make the veneers flat.

• After waiting a few days, and replacing the wet newsprint with fresh, dry sheets a few times, the warped veneers should come out perfectly flat (figure G).

  Figure F

  Figure G

  
  

  Figure H

  
  

Commercial veneers are typically cut very thin, and have a tendency to split when handled. To prevent this, tape the edges of the veneer. The tape will prevent the edges from cracking further. You can use the same taping technique when you cut commercial veneers:

Tape off the intended seam, and carefully cut the veneer using a razor knife (figure H). The tape will prevent the edges of the veneer from splitting.

When working with multiple sheets of veneers, here's a tip for getting all of the edges flat so that they line up evenly when edge-gluing.

• Neatly stack the veneer strips between two boards of poplar. Once the package is temporarily clamped together (figure I), use screws to secure the poplar boards tightly together.

• Use a straight-edge to draw a straight line near the edge of the poplar, then cut to the line at the band saw (figure J).

  Figure I

  Figure J

  
  

  
  

• Next, flatten the same edge at the jointer (figure K). This will leave the edges of the sandwich flat and square.

• To compress the veneers between the cauls, add a lot of clamps. Then make one pass using a hand-held router and flush-trim bit between the clamps (figure L).

• Reposition the clamps one at a time, then make a final pass to finish the ends. This technique will also leave the edges flat, square and ready for glue-up.

  Figure K

  Figure L

  
  

  	Figure M
  	Figure N

  
  

Veneer panels are created by placing veneers on the top and bottom of a substrate -- typically made from MDF or plywood. Plywood is a good choice as long as it's flat and smooth, but many woodworkers prefer MDF as a substrate. Placement of veneers on both sides of the substrate is necessary to achieve proper balance and equilibrium. Even thin veneers can undergo seasonal movements. Adding a veneer only to one side creates an imbalance that could eventually warp the substrate.

David suggests balancing a featured veneer on the top surface with a lesser-quality veneer on the underside. For the demilune table created in an earlier episode, the substrate featured a madrone-burl veneer top balanced with a cherry wood veneer on the bottom (figure M).

The occasional table featured in another episode used a walnut-burl top (figure N) balanced with straight walnut veneer on the bottom. Since the bottom veneer is not generally visible, this was a good method for saving considerably on cost while still offering the necessary structural balance.

	Figure O
	Figure P
	Figure Q
	Figure R

Here are the basic steps for creating a veneer panel. We used karelian-birch burl for the top veneer and curly oak for the underside of the substrate.

• Apply slow-setting resin glue to the first side of the substrate (figure O) and spread it evenly using a glue roller.

• Place the first veneer sheet on the flat surface, then set the substrate -- glue-side down -- on top of the veneer.

• Apply glue to the top side of the substrate and spread it with a roller so that the glue is evenly spread, without gaps.

• Set the second veneer in position on top of the substrate (figure P).

• Align the edges of the wood "sandwich" with blue carpenter's tape (figure Q).

• Position the taped veneer sandwich between two cauls that have been covered in plastic, then slide the whole assembly into the vacuum press. The plastic will prevent the glue squeeze-out from sticking to the cauls.

• Turn on the vacuum press to allow the veneers to bond (figure R). With the air pulled out of the vacuum press, it forces more than 1500 pounds of pressure per square-foot onto the wood sandwich. The consistent pressure, left overnight, will bond the veneers to the substrate as if it were a solid piece of wood.
  

  
  

RESOURCES :

Woodworking Techniques: Best Methods for Building Furniture from Fine Woodworking
Author: Editors of Fine Woodworking magazine
Publisher: Taunton Press
ISBN: 1561583456

David Marks Website
David Marks, DIY's Wood Works host, is a master woodworker. For more information on cut sizes and project details, please contact him via his Website at www.djmarks.com

Woodworker's Guide to Wood: Softwoods, Hardwoods, Plywoods, Composite, Veneers
Model: 080836878
Author: Rick Peters
(2000)
Sterling Publishing Co. Inc.
Website: www.sterlingpub.com

Fine Woodworking
A magazine devoted to high-quality craftsmanship in woodworking.
The Taunton Press Inc.
Website: www.taunton.com

GUESTS :

Bob Nichols
Exotic Hardwoods & Veneers
Oakland, CA
Website: www.exotichardwoods.com