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
Backer Veneer

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

VeneerSupplies.com

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. MDF is notoriously smooth and can be non-porous if it's sanded too smoothly at the factory. It's always a good idea to prep MDF by sanding it first.

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 backed veneers.
  • Yellow glue should not be used with veneer. It doesn't dry hard and it has a tendency to allow bleed-through. This is, by far, 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 veneering, their only benefit is higher moisture and heat resistance.
  • Standard "cold press" veneer glue is the best choice. In my opinion, the Better Bond veneer glue is the ideal blend for veneering because it dries fast and rock-hard. It doesn't require mixing and it's very forgiving in its application.
  • Heat Lock and other iron-on glues can not be used with a veneering project that has seams.

3: Use a Glue Roller

For standard cold press veneer glue and PPR's such as Ultra-CAT, a dedicated glue roller is ideal. I've found that the easiest way is to use a dedicated glue roller. I'm not talking about the $200 imported rollers with the glue hopper on top. I prefer something simple like the one shown on the right. Of course, you can get them at VeneerSupplies.com and help support this ad-free article.

The key to applying glue is to put it on evenly. 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 have the right amount of glue.

Always apply glue to the substrate material, not to the veneer.

 

Glue Roller

Glue Video

4: A Backer or Balance Veneer Minimizes Warping

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 backer or balance veneer should be used on the reverse 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 backer veneer use on this page.

5: Vacuum Press the Panel for Best Results

A vacuum press is the ideal tool for clamping veneer to a substrate because it applies evenly distributed pressure 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 rigids 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

Standard cold press veneer glue needs about 60 minutes of press time to "set" the veneer glue. Remember, the actual cure takes another 4 to 6 hours so be sure to let the panel dry completely before you do any sanding or machining.

PPR's and urea resins require 4 to 6 hours in the press. These glues do not require air to evaporate the liquid in the adhesive so they can generally be machined immediately after they are pulled from the press.

Don't leave a panel in the press for much longer than the glue specifies. For some veneer adhesives, this can cause the glue to get "globby" which won't let the panel cure evenly. Leaving panels in for too long can also allow mold to grow. I've seen cherry develop patches of mold in less than 6 hours.

Prevent panel warp by allowing both sides of the panel to dry evenly. This is another easy technique that only requires you to place the panel on a flat surface with a few dowels under it until the glue has cured. 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 glue runs that have dripped down the sides.

Instead of cutting the substrate to the exact size, I prefer to cut my substrate panels one inch larger in both directions and then apply a veneer that is a half inch smaller than the substrate. I will 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 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.

Cutting veneer with a table saw requires a sharp blade. I prefer a saw blade designed to cross cut plywood but my standard blade typically works very well if I keep the blade high so that the cutting action of the teeth is on the downward movement of the blade. Warning: I don't recommend doing this because it is dangerous to have excess teeth above the part which is being cut.

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 also from 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 pencils if the veneer requires any grain filling or if the raw veneer required a patch piece.

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

Yes, Joe is a practicing Catholic
The Vac FAQ
Heat Lock Veneer Glue