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How hardwood lumber is processed, from the saw to the part
The sawing pattern sets the figure, the kiln sets the stability and the yard sets the edges. Who does which step decides what you can order and how you compare quotes.
Sawing patterns
How the log meets the saw fixes the angle of the growth rings in each board. That angle decides the look, how much the board moves across its width and how much lumber the log yields.
| Pattern | Ring angle to the face | Look | Movement | Yield and price |
|---|---|---|---|---|
| Plain sawn (flat sawn) | Rings meet the face at under about 30 degrees | Cathedral figure on the face | Moves most across the width | Highest yield, lowest price |
| Quarter sawn | Rings at about 60 to 90 degrees to the face | Straight grain, ray fleck in oak and sycamore | Most stable across the width | Lower yield, priced above plain sawn |
| Rift sawn | Rings at about 30 to 60 degrees to the face | Tight straight grain on all four faces, little fleck | Stable, even on legs and rails | Lowest yield in oak, usually the highest price |
| Live sawn (through and through) | All angles in one board | Mixed figure, slabs keep the edge | Mixed | High yield, sold for slabs and character work |
Typical. Many mills sell quartered and rift together as a mixed bundle unless you ask for them sorted.
Drying routes
Green hardwood often carries more than half its dry weight in water. Removing it too fast causes surface checks, honeycomb and internal stress. Removing it too slowly invites stain and mold. Mills combine the routes below to suit species and thickness.
- Air dryingDown to about 20 to 25% before the kiln, or 12 to 20% as finalStickered stacks under a roof. Cheap and gentle, slow and weather dependent. Often the first stage for thick oak.
- Predryer or fan shedControlled first stageLow heat with forced air takes green lumber down evenly before the kiln. Lowers check risk on species that crack easily.
- Conventional kilnTypically 6 to 8% for interior useSteam or hot water heated chambers run a schedule of temperature and humidity steps, then equalize and condition the charge.
- Dehumidification kilnLower temperature, heat pump drying. Common at smaller mills and for species that stain or check at high heat. Typically 6 to 8% for interior use.
- EqualizingAt the end of the schedule the kiln holds conditions so the wettest boards catch up with the driest. This narrows the spread inside a load.
- ConditioningA short high humidity step that relieves the stress left in the shell. Skipped conditioning shows up as boards that cup or pinch the saw when ripped.
- SteamingWalnut is often steamed to darken the sapwood toward the heartwood color. European beech is sold steamed (pinkish) or unsteamed (pale). Say which one you want.
Grading and tally
After drying, an inspector grades each board under the NHLA rules, usually from the poorer face, measuring the clear cuttings it yields, and records surface measure and board feet on a tally. Grade and tally travel together on the invoice.
Grade says how much of a board is clear. It does not say color, figure or sawing pattern. Those are separate sorts you add to the order. The species reference lists the color sorts common for each wood.
- Rough tallyBoard feet on the nominal rough thickness, the normal basis for hardwood prices.
- Net tallySome yards tally surfaced stock on the finished size. Ask before you compare quotes.
- InspectionAsk whether the grade was set by a certified inspector and whether a reinspection is possible in a dispute.
- Color sortWhite maple, sap free walnut or red and white hickory are sorts on top of grade, priced extra.
Surfacing, ripping and dimension work
Everything after the kiln and the grade is secondary processing. A yard may surface and rip. A dimension plant goes further and ships finished blanks, glued panels and machined parts. Tolerances are typical starting points to agree, not standards.
| Step | Where it is done | Typical tolerance or output | What to write on the RFQ |
|---|---|---|---|
| Surfacing (S2S, S4S) | Planer or double surfacer at the mill or yard | Thickness tolerance agreed per order | Final thickness, and whether the tally is rough or net |
| Straight line rip (SLR1E) | SLR saw at the yard | Commonly within about 1/32 to 1/16 in over 8 ft | One edge or two, and the allowed straightness |
| Gang rip to width | Gang rip saw at a dimension plant | Width often held to about plus or minus 1/32 in | Strip widths and the extra allowance for jointing |
| Cut to length and defecting | Optimizing chop saw | Lengths to a cutting list | Clear or sound defects allowed on each face |
| Finger jointing | Dimension plant | Continuous lengths from short clears | Glue type and whether joints may show |
| Edge gluing to panels | Dimension plant | Panel width and thickness to the drawing | Strip width range, color matching and glue type |
| Moulding and turning | Moulder or lathe | Profile to the knife or drawing | Profile drawing and a sample length |
| Sanding | Wide belt or profile sander | Grit agreed per part | Final grit if you finish the part yourself |
Moisture checks that hold up
A load can average 7 percent and still carry boards at 12. Those are the boards that move after machining. A useful moisture spec names the average, the single board limit and how it is measured.
Pin and pinless meters are fine for routine checks within their range. The oven dry method in ASTM D4442 is the reference when a reading is disputed. The Wood Handbook from the USDA Forest Products Laboratory covers drying and moisture in depth.
- At the millKiln samples weighed through the schedule and a final check before unloading.
- Before shippingMeter readings across the lift, top, middle and bottom, not just the outside boards.
- On arrivalYour own check before the stock goes into production, and a record kept with the tally.
- Thick stock8/4 and up can be dry outside and wet in the core. Ask for a core reading or a cut sample.
How we match on processing
We are a matching service, not a sawmill, and we hold no stock. The steps you need tell us which kind of supplier fits. Rough kiln dried lumber goes to mills and concentration yards. Surfaced and ripped mixed lots go to distribution yards. Blanks, panels and parts go to dimension plants. We pass your spec to up to 3 suppliers that already work that way and reply within 24 business hours.
See hardwood applications for the grade, thickness and drying usually ordered for each end use.
What moisture content should kiln dried hardwood be?
For interior cabinets, furniture, millwork and flooring in most of North America and Europe, the usual target is 6 to 8 percent. Put the average and the upper limit for any single board on the RFQ, for example 6 to 8 percent average with no board above 9 percent.
Is quarter sawn lumber worth the extra cost?
It is when width stability or ray fleck matters: wide panels, flooring in rooms with big humidity swings and Arts and Crafts style oak. For paint grade work or narrow parts, plain sawn usually does the job at a lower price.
Can a supplier sell me finished dimension parts instead of boards?
Yes. Dimension plants cut kiln dried lumber into blanks, squares, glued panels and machined parts to a cutting list. You pay for the part rather than the board foot, and you skip the yield loss in your own shop. Say on the RFQ that you want parts and attach the list.
How do I know lumber was dried correctly?
Check moisture with a meter on arrival, and for disputes use the oven dry method. Ask the supplier whether the charge was equalized and conditioned. Boards that bow or cup as soon as they are ripped often carry drying stress, also called case hardening.
Guides on each step
- Grades and Specs
Quarter Sawn vs Rift Sawn vs Plain Sawn Hardwood Lumber
How plain, quarter and rift sawn hardwood differ in grain, stability, yield and price, and how to write the sawing pattern on an RFQ so you get what you mean.
- Grades and Specs
Kiln Drying Hardwood: Schedules, Case Hardening, Checks
How kiln schedules dry hardwood, why boards check or case harden, and what to ask a supplier about conditioning, stress tests and final moisture content.
- Grades and Specs
Lumber Moisture Meter: Pin vs Pinless and Accuracy
Pin and pinless lumber moisture meters compared: how each works, typical accuracy, species and temperature settings, and a simple way to check a hardwood load.
- Grades and Specs
Straight Line Rip and Gang Rip Lumber: Edge Options
Edged, straight line ripped and gang ripped hardwood compared: what each edge option means, how it affects yield and stress, and how to write it on an RFQ.
- Species
Steamed vs Unsteamed Walnut: Color, Yield and Price
Steamed and unsteamed black walnut lumber compared: how steaming changes sapwood color, yield for visible parts, finishing and price, and how to order either.
- Grades and Specs
NHLA Lumber Grades Explained: FAS, Select and Common
How NHLA hardwood grades work: clear cuttings, minimum board sizes and yields for FAS, Select, No.1 and No.2A Common, and how to pick the right grade to order.
Know the processing you need?
Send species, grade, thickness, drying, surfacing and board feet. We pass it to up to 3 mills, yards or dimension plants that fit and reply within 24 business hours.
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