Milled Lumber
The right cut is what turns a stack of lumber into finished work. Mason’s Mill runs S3S and S4S dimensional stock, custom profiles, slatwall, and moulding-grade runs across a deep species list — hardwoods, softwoods, and modified woods like Accoya® — surfaced to spec on our own equipment and quoted alongside the hardware and finish you need to install it.
Custom Milling, BuiltAround Your Project
Every project has a cut list the yard down the street can’t fill. A non-standard thickness. A one-off slatwall profile. A species the big-box stores don’t carry. Random-width S3S that has to yield efficiently against a specific board foot budget.
That is the work Mason’s Mill was built for. We surface hardwoods, softwoods, and modified woods to your exact dimensions — 1×2 through 1×12 in stock S4S, laminated wide stock, S3S random-width for maximum yield, and custom profiles milled to a drawing. Every run goes across our own moulders and surfacers, so tolerances, grain orientation, and finish quality are ours to own end-to-end.
Browse Our Milled Lumber
Thermac Poplar — Cutek Extreme Clear Finish
Thermac Poplar is a thermally modified Appalachian hardwood produced by Bingaman & Son Lumber from native Pennsylvania yellow poplar. Using only heat and steam — no chemicals, plastics, or additives — the wood is heated in a low-oxygen environment to fundamentally alter its cell structure. This process removes the sugars and moisture that fungi and insects need to survive, while permanently reducing the wood's ability to absorb water. The result is a stable, rot-resistant hardwood with a warm, chocolate-brown color that runs consistently through the entire board, not just the surface.
Yellow poplar is particularly well-suited to thermal modification: it's a domestically abundant, fast-growing hardwood that emerges from the process with excellent dimensional stability, a smooth grain, and a rich color that rivals more exotic species. Independent testing on thermally modified yellow poplar has demonstrated Durability Class 1 ("very durable") performance against wood-destroying fungi, placing it in the same durability tier as many tropical hardwoods.
Each board is finished with Cutek Extreme Clear, a penetrating oil that migrates deep into the wood fibers rather than forming a surface film. Cutek's core function is dimensional stabilization — it works from inside the board to slow moisture movement, which is what causes cupping, checking, and end-splitting in exterior wood. Because the finish penetrates rather than coats, it cannot peel or flake, and maintenance requires no sanding or stripping — just clean the surface and re-apply when it looks dry. The clear formulation adds no pigment, so the poplar's natural thermally-modified brown will show through initially and gradually transition to a silver-gray patina if left unmaintained with a colortone.
Ideal for exterior siding, soffits, porch ceilings, cladding, and covered outdoor applications where a domestic hardwood with contemporary durability is desired.
Specifications
| Spec | Detail |
|---|---|
| Species | Yellow Poplar (Liriodendron tulipifera) — thermally modified |
| Product Line | Thermac by Bingaman & Son Lumber |
| Origin | Appalachian / Pennsylvania hardwood |
| Modification | Thermal modification — heat and steam only, no chemicals |
| Finish | Cutek Extreme Clear (penetrating oil) |
| Finish Type | Oil-based, non-film-forming |
| Color | Rich chocolate brown, consistent through the full board |
| Weathering | Silvers to gray patina over time if not maintained with colortone |
| Durability Class | Class 1 ("very durable") when tested per EN 350 standards |
| Janka Hardness | ~500–615 lbf (thermally modified yellow poplar) |
| Dimensional Stability | Significantly improved vs. untreated poplar; tangential/radial movement ~1.1–1.2% |
| Service Life | Designed for up to 25 years in exterior applications |
| Applications | Exterior siding, soffits, porch ceilings, cladding, covered outdoor living, trim |
| Maintenance | Clean and re-oil with Cutek Extreme as needed — no sanding or stripping required |
| Sustainability | Domestic, fast-growing hardwood; chemical-free modification process |
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What You'll Find on the Shelf
A working milled-lumber inventory for cabinet shops, custom builders, millwork specifiers, and finish carpenters:
S4S Stock Hardwoods
Alder, Knotty Alder, Cherry, Hard Maple, and Cypress surfaced, sanded, and straight on all four sides. Available 1 x 4 through 1 x 12, with laminated 1 x 12 in Alder and Knotty Alder for wide-panel work. Ready for cabinetry, furniture, trim, and one-off shop projects.
S3S Hardwoods
Alder, Knotty Alder, Cherry, and Hard Maple in random-width, surfaced-3-sides stock with two smooth faces and one straight edge. Built for maximum yield on cut-list-driven runs where board foot economy matters.
Modified & Sustainable Woods
Accoya® S4S decking, acetylated softwood carrying a 50-year above-ground and 25-year in-ground / freshwater guarantee. No additional oil or finish is required to hit those numbers, and it mills cleanly for custom rainscreen, cladding, and exterior trim profiles.
Custom Profiles & Slatwall
MC-1715, MC-3237, and MC-5850 slatwall profiles milled to specification in the species of your choice, plus custom moulding and cladding runs from our profile library or your drawing.
Specialty & Rustic Stock
Including Forever Barnwood reversible shiplap — 100-year-old weathered knotty white pine with a reversible weathered / circle-sawn face for accent walls, ceilings, and rustic feature work.
Milled Lumber That Pairs With the Rest of the Job
We built the milling program around the projects we already supply. That means the S4S stock, S3S random-width, and custom profiles on our rack are the same ones we quote alongside your hardware package from Blum®, King Slide®, or CGS, your CUTEK® finish system, and your Thermory® or Accoya® exterior wood package.
Send us the cut list, the drawing, or the sample. We’ll match species, mill to spec, and bundle lumber, hardware, and finish into one quote — one point of contact, one delivery, one invoice.
Frequently Asked Questions
S4S ("surfaced four sides") is dimensional stock — sanded smooth and straight on all four sides in fixed widths (1 x 4, 1 x 6, 1 x 8, 1 x 12) and ready to go straight into cabinets, furniture, and trim. S3S ("surfaced three sides") is random-width lumber with two smooth faces and one straight edge, sold for maximum yield on a specific cut list. If you're building to standard nominal sizes, order S4S. If you're ripping to a custom width or optimizing board foot cost, order S3S.
Alder, Knotty Alder, Cherry, Cypress, and Hard Maple are stocked as dimensional S4S in 1 x 4, 1 x 6, 1 x 8, and 1 x 12. Alder and Knotty Alder 1 x 12 are laminated wide stock. Additional species can be milled to order — send us the cut list and we'll quote it.
Yes. In addition to our library of stock profiles — including the MC-1715, MC-3237, and MC-5850 slatwall profiles — we run custom moulding, cladding, and slatwall profiles to specification in the species of your choice. Send the drawing or a sample and we'll match it on our moulders.
Accoya® is acetylated softwood — chemically modified so the cell structure no longer absorbs water the way untreated wood does. That gives it a 50-year above-ground and 25-year in-ground / freshwater guarantee, and it doesn't require an oil or finish to hit those numbers. We stock Accoya® as S4S decking and can mill it to custom profiles for rainscreen, cladding, and exterior trim.
Rustic and knotty grades — Knotty Alder, Forever Barnwood, and similar — contain tight, sound knots throughout the boards, which is part of the look. Some knots may shake loose or fall out during the milling process, and Mason's Mill is not liable for those defects in mouldings produced from knotty grades. Order clear grades (Superior Alder, Select & Better Cherry, S&B 1&2 Hard Maple) when you need a knot-free run.
Yes. Most species and profiles are available as $10 samples, and the sample fee is credited back against your full order. It's the fastest way to confirm grain, color, and profile before we cut a job to size.
Both. We work with architects, builders, cabinet shops, and contractors on trade terms, and we're also open to homeowners buying for their own projects. Trade accounts get pricing tiers and dedicated contact support — reach out if you'd like to set one up.
Yes, and we recommend it. Bundling milled lumber with Blum®, King Slide®, or CGS hardware, CUTEK® finishes, and Thermory® or Accoya® decking means one point of contact, one delivery, and one invoice — the same way we already handle M3 Custom Millwork Shop projects.
Use the Request a Quote button on this page, call your Mason's Mill contact, or stop by the yard. Include the species, dimension, quantity, and profile (or attach a drawing). If you're not sure yet, describe the project and we'll do the spec work.