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Thread: Wood Basics

  1. #1
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    Default Wood Basics

    I thought perhaps it a good thread to address the basic things to look for in wood furniture, under the premise that an educated consumer can make a wise decision. So let's give this a try and not target "brand names" so much as general questions on furniture.

    This could be a LONG thread and make take quite a few posts to cover topics, but let's get started!

    Solid wood is preferable to veneers (which are laminates over a secondary wood) Wider boards are more expensive than narrow boards in solid woods, and more desirable. There are different grades of wood within a type. For example, there are over 200 species of pine and while Southern Yellow is not very good for furniture making, Eastern White Pine is. A cabinetmaker selects his wood based on his project and costs. If he is using an aniline dye and shellac coats, he needs a higher grade of lumber than if he is using covering stains that mask the wood flaws and mineral deposit variables.
    Which wood to get? This varies by price and characteristics. Just because a wood is soft, doesn't mean its not suitable for a project. Here's a rundown of some common woods in the USA that are furniture grade:


    Pine. Soft, but relatively stable. Eastern White has good, tight knots that will not fall out. Shrinkage and expansion is moderate. Dent resistance is poor. Takes stains nicely.


    Poplar. Great Secondary wood (drawer bottoms, etc.) and very stable. Inexpensive. Halfway between a soft and hardwood. Takes paint well, but never stains up nicely.


    Cherry. A great lumber! I personally find it more interesting to look at than most mahogany. Its a hardwood, but not as dense as maple. Takes aniline dyes beautifully and requires little or no sealer. Cherry will darken and 'ruby up' with age and exposure to sunlight. If you use it for flooring or kitchen cabinets, expect deeper and more red dish colors to develop over time nearer the windows of your home.


    Mahogany. Poor Mahogany! So misunderstood! Mahogany grows in every part of the world, and varies greatly. Figured mahogany is highly desirable (aka as 'plum pudding' or 'crotch' mahogany) but you rarely see it outside of veneers due to the cost of those logs. The very best furniture grade mahogany is from Central America and Cuba, but is very hard to source. African mahogany is decent, and the stuff from China and the Philippines the least desirable. Mahogany can be done in open pore, semi-closed pore, and fully sealer finishes. Mahogany is a favorite for carvers, as it carves easily and is not prone to splitting when being handled.


    Maple. Both hard and soft maple is an industry standard. Very durable, very dense, accepts many colors nicely and stains up well. Excellent for the best upholstery frames. Stable, and plentiful.


    Figured Maples. Sometimes called Tiger Maple, or Curly Maple (one of my favorites). A small percentage of maple will be highly figured and is pulled off at the mill to sell to furniture makers and musical instrument makes for about 2x the price of regular maple. Tiger maple MUST be board matched and typically a single log will be used to make a project, rather than taking a board from this pile and another from another pile. Consistency is key, and you will hear the term 'bookmatched' used frequently in figured maples. Figured maples look best with aniline dye finishes and hand-scraped surfaces. Birdseye maples are in this category as well, but are so unstable that most shops only use them veneers.


    Walnut: A hard wood to work with. Not many walnut forests, and most cabinentmakers loathe making walnut pieces for two reasons. First it much be bleached before it can be finished, otherwise its ugly. Secondly, it has to be filled and sanded. Very time consuming to do properly, but quite a handsome wood when done right (3/4's of all walnut pieces I see is NOT done right)


    Oak: Another mainstay wood. Very durable, and dense. Not widely used in fine furniture because of the grain pattern.


    Wood has to be milled to make is usable. It is run through planers, joiners and wide belt sanders to get it to size. The larger and thicker the board, the more expensive it will be. Bed posts and pedestal bases on tables are very expensive to do as solid, non-glued-up pieces. So if you buy a bed, check to see if you see a vertical seam in the lumber which signifies a glue-up. Nothing wrong with glue-ups, just don't pay the price of solid 1-board.


    Industry standard is 4/4 (pronounced four quarter) lumber, which when milled will finish out to 7/8" thickness. Anything thicker - or even thinner - requires more expensive wood or more planing time if being thinned out.
    Once the wood is planed, it either goes to a wide belt sander or is hand-scraped. If hand-scraped (much more desirable) you will feel a slight ripple when you run your hand over the surface. Belt-sanded items will be perfectly smooth. Cutting the surface of the wood gives you a brighter finish over a sanded surface in a completed product.


    Solid wood MOVES. The wider the board, the more it will move with the seasons. Expands in the summer, shrinks in the winter. The art of the furnituremaker is to build to allow this movement, without sacrificing joinery strength. Narrow board furniture does not move nearly as much, and plywoods and veneers don't move at all.


    Joinery. The gold standard is Mortise and Tenon. That's the strongest joint where you have intersecting pieces of wood. All mortise and tenoned pieces will have one or two distinctive wood pins visible from the outside of the piece that secure that joint. Next up is Dowel joints. Not as durable as mortise and tenon, but superior to a bolt-in leg. Dowel joints look like M&T joints, but don't have the cross pins. Last choice are legs than bolt on, or are held on by screws. Plastic blocks, staples, nails, hot glue and the like are unacceptable as joinery methods.

    Bolts are not good because the joints are not strong. Now if you think about this for a bit, it will become clear to you. Bolts are great for holding metal pieces together, like car engines or machinery, where you can pass the bolt and nut through and clamp it tight, or weld a stud to a piece of steel. You are joining metal to metal.

    What happens to wood if you overclamp it? It crushes. But even more so, wood itself cannot hold a thread, it will pull out under high stress. That means you have to either drill through the wood entirely and use a nut on the other end (too unsightly on your exposed wood plus the crush factor), or you have to drill a hole in the wood and place a nut insert into it. Well, nut inserts can't take much torque at all or they break out or blow out.


    A mortise and tenon joint is the strongest wood-to-wood joint you can make with intersecting pieces. You have a tenon (or the male part) and the mortise (the female part) that if properly cut, mean a very tight fit that will not come lose or wobble. The tenoned part has a shoulder on it as well that rests against the mortise base further stabilizing the joint. The pins you see are the cross-locking devices to keep the tenon from pulling out of the mortise.


    Glue by itself is not satisfactory to hold any joint. It's done supplemental to the joint itself. Glue bonds break over time, and then you get pieces that have a joint that flexes, so the cross-pins are mandatory on a mortise and tenon piece. If a salesman tells you the joint is Mortise and Tenoned, and you don't see the pins, then its NOT ! What you have then is most likely a dowel joint, where two fluted dowels are inset into one piece, two holes drilled in the other side, some glue on the dowels and its clamped together. Won't last.


    One interesting tidbit on Mortise and Tenon joints is that a real cabinetmaker only puts them together once. You don't 'test fit' them, as that weakens the joint. They will be precision cut, then a small amount of glue coated onto the tenon, then lightly pounded into the mortise until bottomed out. The the locking pins are drilled and inserted. Now you have a joint that will last for several generations.


    One other note on M&T joints. This doesn't have to do with strength, but just denotes ones that are done by hand vs. ones done by machines. If the mortise is square in the corners, it's done by hand. If it has a rounded radius, its' done with a plunge router or CNC machine.

    If you're buying a windsor style chair, you really want to purchase "bore and wedge" constructed chairs for longevity. That means each leg penetrate the seat of the chair, and each spindle does the same to the bow. Look closely and you will see a wedge driven into the splines. This method of construction assures the legs and spindle will not loosen over time, and doesn't suffer the glue joint failure of 'pound-in' legs held with just glue (we in the trade call that 'bang up' furniture).


    Dovetails. Just like Mortise and Tenon, the strongest way to hold wood intersecting at 90 degrees. Doesn't matter if they are hand-cut or done on a jig, the key is for the pins to fit tight with no slop. And they can only be fit together one time as well. English dovetails are very finely done, with narrow pins. American dovetails are larger and have fatter pins. Nailed together drawers can't even come close to matching the holding power of a dovetailed drawer. In old-world pieces drawer bottoms should be of solid secondary wood (typically pine or poplar), but many pieces today use laminated plywood to save costs.
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

  2. #2
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    Another thing to touch on is finishes. Folks get confused on finishes but here's a basic primer...not meant to cover every nuance - just the most common.


    If you have high-quality wood, you can use ANILINE DYES on your finish, which highlights a beautiful grain in the wood, particularly if used with Shellac build coats. If your wood is of lesser quality, or they don't take the time to bookmatch the boards, then you'll most likely have an oil-based OPAQUE stain applied, which is almost paintlike. It covers the flaws in the woods and makes a uniform appearance across the surface. Obviously, the aniline dyes make for a nicer piece, but they will fade in direct sunlight.
    One you have the color coats set up, you most commonly will have a heat-resistant lacquer or a polyurethane topcoat. Shellac by itself cannot stand water or high heat, so while it makes a beautiful mid-coat, its poor as a final topcoat. Either lacquer or the poly is good, doesn't matter too much as long as your piece doesn't have too much on it. If you have a high build on it, it tends to scratch easily and looks bad over time. The best pieces tend to have light topcoats on them. If the build is heavy, its because the wood underneath is not a very good grade.


    How to protect your table tops. I never fail to be amazed at how few people won't order table pads to cover their expensive new dining room table. Typically $ 200 to $ 250 a set, they really save your topcoat when used while dining.


    Its not water that kills your table finish, its HEAT. Hot items on your table 'relax' the finish and allow humidity to come under the topcoat, then when the topcoat firms up again you have a white blush under the surface. The most damage I see is from Pizza Boxes, where you place the just-delivered pizza on the table while you pay the driver, and that minute it sits there is long enough to cause heat damage. Always use a trivet to place hot items on the table, napkins and placemats are not enough. If a box, plate or bowl is too hot for you to hold barehanded, its too hot for your table top.
    While I think about it....little girls with fingernail polish remover (acetone) will wreck havoc on any wood finish. Don't let your pre-teens paint their nails on your table tops.

    Waxes and Polishes. You can use silicone-based products like PLEDGE, but it you do, it makes it VERY difficult for a craftsman to ever refinish your table top. The silicone penetrates the finish and goes deep into the wood. Any subsequent attempt to refinish will cause a new finish to 'fish-eye' (which looks like motor oil on a driveway after a rainstorm). Use non-silicone products if you ever think you may want to refinish a piece.
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

  3. #3
    cindyloowoo Guest

    Default Ash case goods

    What about Ash for case goods? I am considering Vermont Tubbs for furniture for my daughter and the salesperson told me they use ash solids.

    Also, what should I look for as far as painted wood furniture (Vermont Tubbs)? Should I have glass cut for the tops of the night table, dresser and desk to protect the surfaces or is that overkill?

    Thanks - great forum!

    Cindy

  4. #4
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    Hi Cindy, and welcome!

    Ash is a very strong wood, in fact its the strongest wood relative to weight, which is why its a favorite for baseball bats. Its very stable, and excellent for steam bending as well. It has an open, porous grain and it actually related to the Olive tree.

    In furniture, it has an unremarkable pattern and as such is seldom used on fine furniture where the craftsman is looking to make a 'showy' piece. You won't get the interesting curl or crotch patterns as you do with cherry, maples, and mahogany.

    Buy it for durability and stability, less so for interesting grain patterns.
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

  5. #5
    Bea Guest

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    Duane, it's so interesting to read above re the making and finishing of wood pieces. Thank you for sharing that with us.

    I have long wondered about shellac, and it seemed like something in the past till someone else mentioned it recently, and then I just read what you said about it above. Did I understand you to say that furniture makers will stain, shellac, and then finish with a different topcoat such as polyurethane or lacquer? What is the purpose of the shallac? Why not just stain and then apply the poly or lacquer topcoat?

    Can shellac be applied over an unknown finish? I have a pair of old dressers, Drexel brand, I'd say 1950s maybe, purchased from an antique store, that have an unpleasant sweet odor in the drawers that I associate with them being "old" and probalby having been in a moist climate (got them from Georgia). Someone said I could remedy this by cleaning the insides of the drawers with denatured alcohol, then coating with shellac. I was going to do this. Does that sound like a good thing to do to you?

    Thank you!

  6. #6
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    Shellac is actually an organic product and hypoallergenic (safe to eat!), made from the cocoon of the Lac bug in india and Thailand. Its sold in flakes, and then you cut it with denatured alcohol, typically in a 50/50 mix. The fresh stuff is always superior to the pre-mixed in the can, by far. It has a short shelf life once mixes, and requires about 8 hours to dissolve the flakes so its best to make the prep ahead of time.

    Shellac was THE finish before the invention of nitrocellulose lacquers. Uses as build and sealer coats it imparts a warm glo to the finish that one can never get with modern industry products. Its easy to use, dries fast. However it has two major flaws. One is it cannot stand up to water, and will turn white if moisture hits it. So its largely unsuitable for table tops unless an additional protective topcoat of lacquer or poly is put over it. Second, it cannot tolerate high heat and will break down or crystalize when exposed to it. We used to have shellac failures in the back of our delivery truck in the summertime, when heat would get to be about 180 degrees in the box. Solved that problem by installing vents in the truck body to keep it below that.

    Yes, top flight makers will use shellac as the build and color coat during a finish layup as it provides spectacular depth to the finish (use orange shellac). However you dont' see this in normal furniture - its too time intensive. Its pretty much limited to hand-made premium pieces.

    Shellac is also excellent as a primer for sealing pine knot holes before painting or staining to prevent bleed through. It would work on your drawers to seal it as well, but I would probably sand the drawers lightly on the interior before cleaning with the denatured alcohol, then apply the shellac THINLY with a brush. Not too much build!
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

  7. #7
    Bea Guest

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    Thanks for that info, Duane, I will lightly sand as you indicate. I already bought the CANNED shellac (clear, not orange). Do you think this will be good enough for the inside of my drawers? They honestly already have a nice rosy glow, I'm betting they were shellacked and are real wood.

    As long as we're on the subject of finishes, what do you think of Bartley's wipe on gel stain and varnish?

    Also -- do you have any idea why the inside of the dresser has the smell? It is a sickly sweet odor. I've sometimes smelled the same smell on clothes that have hung in the closet way too long unworn.

    Bea

  8. #8
    Liz H Guest

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    Hi Bea,

    If you do decide to refinish your furniture, a great place to get advice is the Sawmill Creek forums. A lot of great wood craftsmen hang out there. Sometimes I just love to browse the wood-turning pics they've uploaded.

    http://www.sawmillcreek.org/index.php

    Liz

  9. #9
    Bea Guest

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    Thanks Liz, I'll keep that in mind.

  10. #10
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    Quote Originally Posted by Bea View Post
    Thanks for that info, Duane, I will lightly sand as you indicate. I already bought the CANNED shellac (clear, not orange). Do you think this will be good enough for the inside of my drawers? They honestly already have a nice rosy glow, I'm betting they were shellacked and are real wood.

    As long as we're on the subject of finishes, what do you think of Bartley's wipe on gel stain and varnish?

    Also -- do you have any idea why the inside of the dresser has the smell? It is a sickly sweet odor. I've sometimes smelled the same smell on clothes that have hung in the closet way too long unworn.

    Bea
    Oh sure, canned shellac will be fine for an interior drawer, just don't put it on too heavy.

    Bartley's is a wiping paste varnish. I use it in a rather odd way, to cover the nylon scrub marks when knocking down a poly topcoat, or to lock in a shellac coat to give some water resistance. As a standalone finish out of the can its pretty gross (used as a finish over bare wood). But its excellent to final topcoat with. The secret there on the finals is to put it on so dry with a rag that its barely covering. Most people lather on finish topcoats like they were painting a room with a latex roller. The trick when doing topcoats is to keep the dry and light.

    As to the odor? Probably the wood used as secondary in the drawer. If its plywood or laminate, the outgassing of the glues used in the bonding.
    Duane Collie
    Straight answers from thirty-six years in the business.
    My Private Messages are Disabled - Please ask questions here in the forum.

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