Tuesday, November 27, 2007

Sheet Goods, Veneers, Thicknesses

This photo is a piece of Camphor Burl Veneer from the nice folks at Certainly Wood of East Aurora, NY. This piece's actual size is about 13" x 20". Priced by the square foot, at $8.95 this veneer is moderately high priced. By comparison, Amboyna burl veneer, very rare, is $25/sq. ft. Crotch Mahogany veneer, for appearance no slouch compared to either, sells at around $6.00 per square foot. Other quite stunning species can be very low priced, $2.95 per square foot. See Certainly Wood's Designer veneers. I like the Makore veneer, and plan to use it on my now both unfinished, and unedged kitchen cabinets. When I first began my day job, for thirty days in a row I was assigned to work on the same/or similar large cabinets. The company was sub-contracted to build these for another firm west of Minneapolis. The other company provided the sheet goods, quarter-sawn ash-veneer plywood with MDF cores. (At the completion of the job I scrounged what was going to be thrown out, about 14-20" and 32" by 96" pieces. All my kitchen and bathroom cabinet doors are made of this ply. It will take veneer wonderfully. Read on.) Sheet good? MDF? What, you say. Sheet goods are commonly called plywood. But more accurately, all plywood is a sheet good, though not all sheet goods are plywood. Particle board, particle board core melamines, compressed masonite, MDO, MDF et. al. are all sheet goods. There are lots of sheet goods. The hardwood plywoods alone come in all the northern (temperate zone) species, and lots of exotic (tropical) species. The standard sheet size is 4x8, feet. Common thicknesses are 1/4", 1/2", 11/16" and 3/4". (Watch yourself here though; we work with 3/4" stuff that sometimes is 11/16", and 11/16" +. Spoken aloud, read that plus sign as "strong", and understand by strong I mean 1/32". To me/us, the words strong and shy are nomenclature for 1/32". It 's easier to say, "32 and 13/16th's strong", than 32 and 27/32nds.) "With MDF cores..." MDF stands for medium density fiberboard; it's a sheet good made from compressed cellulose. And by God it is compressed! Four by eight sheets of3/4" MDF weigh eighty pounds. What's it good for? When I had 2000 sq. feet of shop space in Montana, and in St. Louis I made 4x8 workbenches for my students using a piece of MDF on top of a piece of laminate grade particle board. (Forty pounds/sheet.) I used 4x4's for legs and 2x6's for stretchers, and mounted a vice at two opposite corners. I addition to weight, MDF is very,very flat, and exceedingly impact resistant. If one intended to build a home work bench for general home use, MDF on top is very nice. Screw it down with screws intended for deck construction, the square-head screws that look light green. Countersink them so the heads are below the surface. If you ever need to move the bench, the top can be easily removed. It's eight pounds, remember. Avoid the gold and/or black drywall/sheet rock screws as the heads can be easily snapped off. The "Oh sh*t" feeling comes .3 seconds after the snapping sound. Not a heh. (If this happen with sheet goods, one can often pry things loose. But avoiding it is preferred.) MDF, because it is so flat, makes an excellent substrate to which to apply veneers. (Substrate: the board(s) to which veneers are glued. Before sheet goods, joiners and cabinetmakers had to make their own substrates from solid lumbers. A tricky proposition at best because of our next topic, "Wood Movement". Stay tuned.) The better hardwood plywoods have plywood cores with a thin (@5/16") layer of MDF to which the veneer is attached. At this writing, fair hardwood plywoods in the common species of red oak, birch and hard maple can be had at your local Home-Men-Lowe-Depot-ard-'s for about $60 per 4x8 sheet. It's OK stuff, not lousy, not premium. For better quality expect to pay $140 per sheet or so. The lower priced goods will not be flat, but bowed, some by 1-2" over four feet. This can cause problems if one is making some sort of door. We like these sorts of thing to be flat. But for rough and better bookshelves etc., the $60 stuff is OK. Build your kitchen cabinets from the good stuff.

One last word about the thickness of veneers. At Certainly Wood's 'thicker veneers' page, the thicker stuff is (!): 1/32nd, 1/20th, 1/16th, 1/10th. How thick/thin then is the 'not thicker' veneer? Very thin: 1/42nd of an inch. Veneer is cut from logs using either rotary cutters or large slicers. When veneers were hand sawn from logs, stumps and burls, the thicknesses were about 1/10th to 1/8th of an inch. Some contemporary furniture makers in small shops will cut their own veneers. We are, to be sure, limited to small boards or logs, but can then obtain thicker stock. Why does this matter? Appearance. I do not think there is enough wood thickness on sheet goods to do justice to any finish except the film finishes, and they are best applied by spraying. My preferred finish is a fast-dry, thinned wiping varnish. Thinner materials do not, to my, do justice to their species. Curiously though, the veneers not already glued to sheets goods behave somewhat more like their thicker kinfolk. Also, I usually double layer my veneers, applying first plain cherry or mahogany, $1.25-1.75/ sq. ft. I believe the improvement in thickness translates to improved appearance.

One more last word. Why use veneers at all? The log goes further. All the Brazilian Rosewood veneer currently on the market, (the cutting of Brazilian Rosewood has been banned since about 1992), comes from logs cut and/or harvested before the ban. It starts at about $12/sq. ft. But it is beautiful stuff. I'll show you sometime.