We’ve written of wood glues, clamps, and edge gluing in the past here on Obsessed Woodworking, and we’ve either included in our projects or seen wide boards glued edge to edge to create tabletops.
In those edge gluing projects, we were creating width for tabletops and desktops. Clamps held the pieces together while the glue dried, and a chisel or scraper cleaned up the dried glue that had oozed out between the edges.
But what about face gluing? Gluing wood pieces face to face to create a greater thickness to work with? Maybe pine or cherry, gluing wood together to make thicker pieces for table legs, for instance? Or face gluing thinner pieces to make a thicker tabletop?
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Some General Tips on Face Gluing
Glue application and clamping are the two major considerations to surface gluing for additional thickness.
Glue. Be sure to wet both faces of the boards and use a roller to make sure the glue coat is thin and covers the entire surface evenly. You’ll want to give the glue a full 24 hours to cure fully. Don’t worry about glue oozing out along the seam; wipe away excess glue seepage with a damp cloth, and if more oozes during curing, it can be chiseled or sanded away. Don’t skimp on the curing time, either.
Clamping. Have a plan and your clamps ready before you apply the glue, and then when the glue has been applied and rolled, don’t waste time with the clamping. Clamp the pieces evenly across both the width and length of the workpieces. We found a very helpful video that shows an effective way to laminate wood together using both a parallel clamp and a series of F-clamps spaced evenly along the length of the pieces, and you’ll find that video here.
Slip-Sliding. The workpieces are going to want to slip and slide as you clamp. There are several solutions:
- Shooting brads into the ends of the woods both to prevent sliding and to keep them aligned;
- Using a little salt sprinkled in the glue to act as an abrasive to prevent sliding. The salt will dissolve in the glue and present no problem after curing.
But, again, check out the video to show how using clamps effectively can eliminate sliding.
Questions To Consider When Surface Gluing for Additional Thickness
What about the wood grain?
What’s the project? How important to it is the wood grain? If, for instance, it’s a furniture top, and if the board you are using is long enough, cut it in half and fold the pieces together like a book. This will give you a similar, if not exact, grain edge when the pieces are glued together.
Is the additional thickness really necessary?
Could the project still succeed without additional thickness? Let’s stay with the furniture top thought, and your boards are ¾” thick. Does the top really need to be 1 ½” for strength? It’s likely the top at ¾” would be strong enough. In this instance, you can do what cabinet and furniture makers often do – – join a thicker edge all around to give the appearance of thickness all across. It’s a less expensive alternative and economizes on wood use for future projects.
Can plywood be glued face to face?
Sure you can. The same general approach to surface gluing applies when using plywood – – glue application, clamping, and time to cure. Here’s a video that discusses the process using plywood.
As you will see in the video, the ply orientation and direction come into play when using plywood, as well.
Can you glue 2x4s together to make 4x4s?
Once again, the answer is sure you can. The process remains the same, although your project will determine whether all of the steps we’ve outlined above are actually necessary. Here’s a video that shows a very informal use of the 4x4s created by face bluing 2x4s. You’ll save money, too.
Can you face glue bowed boards?
This question gets a qualified yes. Sure, you could try the face glue process we’ve outlined above and use the tightest clamping configuration you can muster. But, over time, that stress may prove to be too much, even with the glue.
The wiser course of action is to remove the bow. Run the board through a planer bow side up to create a smooth and level surface, and then run the board through the planer again cup side up, relying upon the level surface the first run through created.
With the bow now cured, you have a level surface that will take gluing to another level surface well using the basic surface gluing process above.
Your project will determine whether you genuinely need the extra thickness, along with your stock inventory and budget. Extra thickness may be desirable for table legs and for less formal uses such as the 2×4 example we mentioned earlier, and for shorter spans, it can be a pretty easy process.
For furniture tops, you also have the option of following the practices of cabinet and furniture makers and join a thicker edge around the perimeter.
A good glue, plenty of clamps, and time to cure. The basic rules of joining wood apply in surface gluing for thickness, just as in edge gluing for span.