JoeWoodworker
JoeWoodworker Veneer
The Official Website of this Non-Professional Woodworker ™

Part 1
Introduction

Welcome
Veneering Basics

14 Good Reasons
Vacuum Press Uses
Vacuum Press Options
Overview

Questions & Answers
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Part 2a (Option 1 of 2)
Project: V2 Venturi Press

About Project: V2
Parts List
Build the Manifold
Build the Reservoirs
Assemble the Venturi
Make the Carrier
Wire the Press
Testing and Adjusting
Mods and Options
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Part 2b (Option 2 of 2)
Project: EVS Pump Press

About Project: EVS
Parts List
Pump Selection
Build the Manifold
Build the Sub-Manifold
Build the Reservoirs
Make the Carrier
Final Assembly
Wire the Press
Testing and Adjusting
Mods and Options
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Part 3
Vacuum Bagging

Vacuum Bag Basics
Polyurethane vs. Vinyl
DIY Vacuum Bags (A)
DIY Vacuum Bags (B)
Connect the Bag
Bag Closures
Bag Platens
Breather Mesh
Maintenance
DIY Frame Press

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Part 4
Veneer Information

About Veneer
Veneering Glossary
Veneering Myths
Balancing a Panel

Veneer Glues
Veneering Tips
Substrate Materials
Flattening Veneers
A Sharp Veneer Saw
Jointing Veneers
Taping Veneers
Dealing with Defects
Curing Glued Panels
Veneering w/o Vacuum
Hammer Veneering
Iron-On Veneering
Veneer Storage
Amazing Bookmatches
Copper Veneer Guide
Paperbacked Veneer

Edgebanding Guide
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Part 5
Miscellaneous Info

Vacuum Press FAQ
Veneering FAQ
Veneer Glue FAQ
Copper Veneer FAQ
Vacuum Forming
Vacuum Chucking
Vacuum Clamping Pedal
Vacuum Clamping Jigs
Vacuum Clamp Matrix
DIY Vacuum Manifold
Vacuum Press Gallery 1
Vacuum Press Gallery 2
Downloads (PDF's)

VeneerSupplies.com

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Vacuum Veneering - Tips, Tricks, and More

Veneering Tips: How to Prevent Veneer Panel Failure

No matter how many times you've used a vacuum press, there's always a moment of slight anxiety when you pull a veneered panel out of the press. You're wondering if there will be bubbles, ripples, delamination, or seam separation. Here are a few tips to ease the worry and avoid the most common mistakes when working with veneer.

1: Prepare the Surfaces Properly

For all substrates
Many substrates require a quick scuff sanding with 80 or 100 grit sand paper. This is especially true for MDF, MDO, and some types of plywood. The substrate surface must be porous for most water-based adhesives to bond.

For paper-backed veneer
Test the back of the paper backed veneer by applying a single drop of water to the backing. If there is still a bead of water after 5 seconds, then the backer is creating the problem with the adhesion. The solution is to scuff sand the backer with 80 or 100 grit sand paper. You can also wipe the backer with lacquer thinner to chemically roughen its surface.

For raw wood veneer
No preparation is needed for most raw wood veneers. However some of the oily exotics will adhere better if it is wiped with naphtha just before application.

2: Choose the Right Glue

Contact cement is only suitable for paper backed and 2 ply veneer. It's a common beginner mistake to use contact cement or yellow wood glue on raw wood veneers. Neither of these adhesives dry hard and yellow glue has a tendency to bleed-through. We recommend Better Bond X-Press™ veneer glue since it dries fast, cures hard and requires no mixing. It is made specifically for raw wood veneer and it's very easy to apply.

  • Contact cement is only suitable for paper backed and 2 ply veneers. Wood veneer with no backing should never be used with contact cement.
  • Yellow glue should not be used with veneer. It doesn't dry hard and it has a tendency to allow bleed-through. This is the most common mistake in veneering. More information about veneering adhesives can be found by clicking here.
  • PPR's and urea resin glues are not ideal for those new to veneering. They require careful mixing and long press times. And for basic veneering, their only benefit is higher moisture and heat resistance.
  • Standard "cold press" veneer glue is often the best choice. We recommend Better Bond X-Press™ veneer glue since it dries fast, cures hard and requires no mixing. It is made specifically for raw wood veneer and it's very easy to apply.
  • Heat Lock and other iron-on glues can be used on veneer projects that have seams (joint lines) but it takes practice to get it right.

3: Use a Glue Roller

Always apply glue to the substrate material and not to the veneer. The easiest way to apply most water-based veneer adhesives is with a simple foam rubber glue roller. These rollers are re-usable and inexpensive. You can get them at VeneerSupplies.com to help support our website and keep it free of annoying advertisements.

The key is to apply veneer glue evenly and the rule of thumb is that the surface of the substrate should look evenly painted with veneer glue. It should not be dripping wet. A good test is to place a pencil mark on the substrate and apply the glue. If you can barely see the pencil mark on the substrate through the adhesive, you likely have the right amount of glue.

 

Glue Roller

Glue Video

Bonus Tip: Veneer can have a tendency to curl up when it is placed on the wet glue layer on the substrate. Do not spray the face side of the veneer with water to counteract the curling. The addition of water to the veneer causes excessive expansion of the wood cells which can cause the veneer to split later in the day as the moisture evaporates from the saturated wood cells.

4: Minimize Warping with a Balance Veneer

One of the most common veneering problems is the tendency of the panel to warp after it is removed from the press. You can eliminate this issue by veneering both sides of the panel. A balance veneer is a veneer that is applied to the back side of the substrate. This will even out the stress placed on the substrate as the glue dries and the veneer settles into its final position on the panel. Learn more about balance veneer use on this page.

Large Panels
A backer or balance veneer can be applied to the panel before or after the face veneer. Most vacuum press users will find it easier to apply glue to the back of the panel and press the backer veneer first. Follow the instructions on the glue bottle regarding clamping time. Better Bond X-Press™ veneer glue requires just 60 minutes of clamping time. When the appropriate amount of time has passed, remove the panel from the press and immediately apply glue to the face side of the panel. Then set the face veneer in place and press the panel for another 60 minutes or as described on the veneer glue instruction label.

Small & Medium Panels
You can save time if your project calls for a small to medium size panel to be pressed. In this case, you can press both sides at the same time. Simply apply the glue to the back side of the substrate and lay the backer veneer onto that surface. Then quickly move on to applying veneer glue to the face side of the panel. Put the face veneer in place and get it under clamping pressure as soon as possible. Press the panel for 60 minutes or as described on the veneer glue instruction label.

5: Vacuum Press the Panel for Best Results

A vacuum press is the ideal tool for clamping veneer to a substrate because it applies a significant amount of even pressure distributed across the entire surface. If you do not have a vacuum press, you can usually get a good finished panel with clamps and weights. The key is to make sure the pressure is evenly distributed. Otherwise, the glue may create ridges and bubbles in the veneer. This will ruin the panel. Click here for more information about veneering without a vacuum.

6: Allow the Panel to Dry Correctly

Better Bond X-Press ™ veneer glue requires 60 minutes of clamping time to "set". Remember that the actual curing takes another 4 to 6 hours outside of the bag. Be sure to let the panel dry completely before you do any sanding or machining.

Don't leave the veneered panel in the press longer than the glue specifies because some veneer adhesives can get "globby" which then causes ripples and bubbles to form in the veneer. Additionally, panels left in the press for too long can develop patches of mold. I've seen cherry and maple develop mold with less than 6 hours of clamping time.

Panel warping can be prevented by allowing both sides of the panel to dry evenly. Small light-weight panels can simply be hung by spring clamps suspended from rope or string. Large panels can be placed on a flat surface with dowels or PVC pipe underneath to allow air flow which creates an even drying of both sides of the panel. For more information, be sure to check out the "Curing Glued Panels" page.

7: Trim the Panel Using the Right Tool

If the substrate was cut to the exact size before the veneer was applied then a flush cutting router bit is typically used to trim the edges. This works very well as long as the edge of the substrate is square, free of voids, and has no dried glue drops that would interfere with the pilot bearing.

Instead of cutting the substrate to the exact size, I often prefer to cut my substrate panels one-half inch larger on each side and then apply a veneer that is a half inch smaller (on all sides) than the substrate. I typically line up one edge of the veneer with one edge of the substrate so that the veneer is inside the edge of the substrate by an eighth of an inch. Then I use blue painter's tape to hold it in place. Once the panel has cured, I use my table saw, with a plywood cross cutting blade, to do the final cutting of the panel. I start by cutting the side opposite from where I lined up the edge of the veneer slightly off the edge of the substrate. Then I go back to the other side and trim the panel to its final side.

8: Avoid Sanding Through the Veneer

It is every veneer user's nightmare to have a perfect panel ruined because the sander cut through the veneer. It's no less than instant disappointment when the glue surface becomes visible. Don't let a worry about sanding through a panel prevent you from veneering a project. I've been there and I've learned from it.

Do yourself a favor and make a couple of test panels using a softwood veneer like walnut or redwood and a hardwood veneer like maple or Karelian birch burl. These panels don't have to be large. Even an 8" x 10" sample works fine. Apply the glue to the substrate, press the panel, and let it cure.

Draw a dozen or more lines across the veneer surface with a pencil. Be sure the pencil lines go all the way out to to the edges of the panel since this is where many sand-through mistakes can happen. Then use your favorite tool to sand the panel. I use a random orbit sander typically starting with 120 grit. Watch the sanding lines disappear and note where they are removed easiest. You will likely find that the edges of the panel are where the pencil lines are removed with the least amount of effort.

Continue sanding the panel and trying various amounts of pressure on the tool to see how it affects the removal of the pencil markings. You would normally stop sanding when the pencil lines are removed and the panel is smooth, but in this case go ahead and keep sanding. The goal here is to sand down to the glue layer so that you get a feel for exactly how long you can sand before disaster strikes.


In the picture above, I used a random orbit sander (with 120 grit sand paper) for
80 seconds on this spot to sand through the veneer.

Consider making a few of these test panels and test mistakes and with that you will have gained invaluable knowledge that will help you avoid sanding through a project veneer panel.

I draw pencil lines on every veneered project in my shop as a reference for the softness of the veneer. If the line is difficult to remove, then I know I have a hard veneer which I will not easily sand through. I also use the pencil trick to help avoid sanding through if the veneer requires any grain filling or if the raw veneer required a patch piece. Sometimes I end up with some light pencil markings left on the veneer but these are easily removed with a little denatured alcohol on a paper towel.

Be sure to check out the Veneering FAQ for more information.

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