Veneering Primer

The following is a slightly edited version (mostly for pagination and spelling :) of an excellent article by Keith A. Lahteine of Audio Box Design, followed by some personal thoughts and comments.

Veneering, Wood and Plastic Laminates

by Keith A. Lahteine

Veneering materials are available in any number of formats. The least expensive is probably rotary cut pieces about 1/32" thick. The next is face cut, followed by quarter sawn of the same thickness. Paper backed sheets, 1/32'' and less in thickness, will cost from $50.00 to $100.00 a sheet (4'x8') depending on species and cut. The last, and most expensive of all, is mica backed wood veneer "Formica Ligna" which sells for $120.00 a sheet and up. Straight mica veneers which carry a photographic type face meant to simulate various wood types, sells from $35 to $75 a sheet. The image face on these laminates is very thin and care must be exercised to avoid harming the surface.

Tools needed to handle these materials are, for the most part, simple and not too expensive. Tools for cutting mica backed wood veneers and plastic laminates are a little more specialized than those needed for straight wood and paper backed veneers. For mica and mica backed plastics, a pair of laminate shears is handy. They come in models for cutting straight lines or curves and cost about $35 each. Some well stocked home supply stores as well as cabinet and laminate supply stores should have them. If you have a table saw you can cut straight lines. When ripping thin laminates and veneers on the table saw it helps to raise the laminate above the table surface with a thin piece of material for the veneer or laminate to ride on. This prevents the material your cutting from slipping under the fence and thus jamming. Cut pieces large enough to allow for about a 1/2" overlap. This will be trimmed off in the final stages of finishing.

Whether you are or are not going to use a grill cloth will decide some of the next steps. If you cover the baffle board completely then the decision is moot. The instructions are for a normal rectangular prism (6 sides). The first surface to be covered is the front (baffle board). Even is you have decided to use a grill cloth to cover the front of the enclosure, having the baffle covered allows the grill to be removed or to remain in place depending on your whims. At least a frame of 1'' or wider can be used to start the veneering process. Next is the bottom of the cabinet which will overlap the front piece. Each piece of veneer or laminate must be flushed before the next piece is applied.

I have received queries as to whether or not the pieces meeting at right angles (90 degrees) should be mitered. Apparently some of the tool manufacturers have responded to this same request. In the past five or six years a miter laminate trimmer has become available to effect this kind of treatment. It is used to 45 the edges of the pieces being joined. Given this specialized tool, the joint is still very hard to produce. The reason for producing this effect is still very much a puzzle to me. It is almost always a requirement to relieve 90 degree corners with the use of a file and/or sandpaper. When this is done, flush overlapping or mitering appear pretty much the same without the use of a magnifying glass. Flush overlapping is easier and much more painless to achieve.

In any event you will need (if working with mica backed laminates) a laminate trimmer with a flush (carbide) bit. The type with a roller bearing on the bottom is the easiest to use. Laminate trimmers are manufactured by a number of different companies which I'll list to the best of my recollections : Makita, Ryobi, Bosch and Porter Cable. These are the best and most accepted of them. Porter cable and Bosch make both the regular as well as miter types. A small router can be substituted for the laminate trimmer but the dedicated trimmer is easier to control. Trimmers can also be purchased in kits which include a number of different bases for varying offset and angle. These usually sell for about $200 and up. A standard trimmer will cost about $80 to $150 and a miter trimmer will sell for about $170 to $200. Next is a standard "Mill bastard" file. About 8'' to 12'' in length is ideal. There are files dedicated for use with laminates but are not necessary.

Contact cements are the next concern you'll have. Most petroleum based adhesives are very volatile and should only be used in areas with adequate ventilation. There are formulas which use non volatile, water based mixes but their performance is less than the petroleum based adhesives. Tack time is from 15 to 25 minutes, depending on temperature and humidity. Waiting a little to long rather than not long enough is preferred. A solvent for cleaning the seams and joints is necessary. Acetone is the best and most effective but can soften and remove too much glue if not used with care. Lacquer thinner will not work as well but is safer to use.

If you are going to use paper backed veneer or straight wood veneer you really don't need a laminate trimmer. What you will need instead is a small veneer saw. This is a small hand tool that costs about $10 . You can't use a laminate trimmer on non mica backed veneers; it will tear them up to easily. When you use the veneer saw to flush the edges always saw in a direction which will be pulling the veneer down. If the veneer starts to separate you're sawing 180 degrees in the wrong direction. Finish up with a sanding block with 150 or 180 aluminum oxide paper. You shouldn't have more than about 1/32'' to remove.

Why I think mitering is such a waste of time and effort has to do with the material thickness you're dealing with. The overlap is only about 1/32'' (thickness of the veneer). Unless you want the corners as sharp as a knife they will have to be relieved with sanding. The radius for each corner can only be the veneer thickness (about 1/32''). That is, potentially, the largest end grain you have to worry about. Even if you were to miter the corners together, you would still have to relieve the corners. That's why I think mitering is a waste of time. If you do a proper job you'll see no difference in the end result.

Okay. Now that I've gotten that off my chest we can get back to the task at hand. Even though you probably won't see the difference, I maintain an order to the sequence of applying the sheets of laminate or veneer. After the front (baffle) is applied, the edges are flushed, the bottom piece is the next to deal with. The sides follow. Remember, each piece has to be flushed to accept the next piece. Don't do any relieving of corners until the entire piece is covered. The last surface, to be applied, is the top. This overlaps both sides as well as the front. If you have any areas that need fill, this is the time to do it. There is an excellent product for filling gaps, scratches and gouges. It is like plastic wood but is available in a number of wood colors as well as natural. It is called "Famowood" and I have found nothing superior. This, or any filler, should be applied before any stain or oil based finish. It accepts stains very well and you would be hard pressed to notice it's use if applied carefully. It also sands easily and this should be done just prior to staining. When you are applying contact cement to the surfaces to be joined only apply to two joining surfaces at a time. Don't forget the edge has to be flushed before the next piece can be joined. When coating the mating surfaces with adhesive, determine which of the surfaces is the more porous and coat this piece second. This way each should reach the same state of dryness at, approximately, the same time. One tool, I have not mentioned, that comes in handy is a J-Roller for applying pressure to the glued surfaces. It makes the job that much easier. A small wood block struck with a hammer all over the glued pieces will work as well. Pre-cut all of your veneer or laminate pieces about 1'' larger than the finish dimension. This allows about 1/2'' overlap all around. After the veneer is applied sand with 220 and stain and finish with good varnish or polyurethane. Very light sanding with 220 between coats. It takes a minimum of four coats (six is even better) to achieve a good finish.

A few tips follow : In order to position the veneer pieces before the glue makes contact, use 1/2'' to 3/4'' dowels to separate the surfaces. (Wax paper will work with smaller pieces) . When you are satisfied with the position slide the dowels or wax paper out and let the glue do it's job. Get it right before making contact; the cement won't give you a second chance. Once contact is made picking it up and re-applying is impossible.  When you're using a veneer saw use a couple layers of masking tape on the surface that the saw will be riding on. This prevents damage to the veneer and the small overlap can be flushed with a sanding block and 180 or 220 paper. The choice depends on caution and courage. Don't hesitate to ask questions or disagree with me about my system. It works for me but then criticism never hurt anybody.

Keith A. Lahteine   "Audio Box Design"   http://www.audiobox.com

Some personal thoughts and comments

1. One very important consideration for non-pre-processed veneers (such as raw wood stock) is that the veneer must be perfectly flat. Veneer conditioners exist for doing this. Pre-processed veneers should be flat already, but check first.
2. I find it easier and more accurate to flush the edges with a hand plane. I find saws to be too rough and more prone to tearing.
3. I'm not a fan of sanding veneers. Many are too thin to begin with and run the risk of sanding through if not done with care. But more important is that I like the beauty of the wood to show through. I prefer to use a cabinet scraper, which never leaves the surface dull looking as sanding does. The result is a surface with more depth, and just as smooth if not smoother than sanding alone.
4. Not all woods will glue correctly with all glues due to their properties. When in doubt, experiment with scrap pieces before commiting your veneer to the glue.
5. Different glues have different properties that may affect their choice for use. For example, the traditional veneering glue of choice - hide glue - allows repairs to be made more easily but is more difficult to use and to apply by today's standards. Contact cement is quick but much less forgiving of mistakes.
6. For those doing this for the first time, invest in extra materials and practice, practice, practice.

28-September-2000

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