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 Ash Dark Roast — Cutek Extreme Clear Finish
Product Description
Thermac Ash Dark Roast is a thermally modified White Ash produced by Bingaman & Son Lumber from responsibly managed Appalachian and Pennsylvania forests. Like all Thermac products, the wood is transformed through a chemical-free process using only heat and steam — no chemicals, plastics, or additives — sustained in an oxygen-deprived kiln for 14–16 hours. The "Dark Roast" designation refers to a higher peak modification temperature, driving the wood to a deep, rich chocolate-brown tone that runs consistently through the entire board — not just on the surface. Because the color is a product of molecular caramelization rather than pigment or stain, the color cannot chip, scratch off, or reveal a lighter tone underneath: whenever the board is milled, cut, sanded, or worn, the same dark brown color remains.
The deeper thermal modification also pushes performance to its peak. Independent testing per EN 350 rates thermally modified ash at Durability Class 1 ("very durable"), on par with tropical hardwoods like teak and ipe, with an expected exterior service life of 25+ years when properly maintained. The high-temperature process breaks down the sugars and hemicellulose that fungi and insects feed on, and dramatically reduces the wood's ability to absorb moisture — cutting water absorption by 60–70% and dropping equilibrium moisture content to just 4–6% (versus 18–22% for untreated ash). This translates to radial and tangential movement under 1%, virtually eliminating the cupping, warping, and seam-opening that plague untreated ash in exterior use.
Each board is finished with Cutek Extreme Clear, a penetrating oil engineered to stabilize exterior wood from the inside out. Rather than forming a surface film like paint or varnish, Cutek carries its oils deep into the wood fibers, where they work continuously to slow moisture movement — the primary driver of cupping, checking, and end-splitting. Because the finish penetrates rather than coats, it cannot peel or flake, and maintenance requires no sanding or stripping — just clean the surface and reapply when it looks dry. The clear formulation adds no pigment, allowing the Dark Roast's deep chocolate-brown tone to show through initially before gradually silvering to a soft gray patina if left unmaintained with a colortone.
Ideal for high-end architectural siding, cladding, soffits, porch ceilings, feature walls, decking, and covered outdoor living spaces where a rich, dramatic dark-wood aesthetic is desired — offering the look of exotic tropical hardwoods with the sustainability of a domestic species.
Specifications
| Spec | Detail |
|---|---|
| Species | White Ash (Fraxinus americana) — thermally modified |
| Product Line | Thermac by Bingaman & Son Lumber |
| Modification Level | Dark Roast — higher-temperature thermal modification for deeper color and maximum durability |
| Origin | Appalachian / Pennsylvania hardwood, USA |
| Modification Process | Heat and steam only, no chemicals; oxygen-deprived kiln for 14–16 hours at ~400°F |
| Finish | Cutek Extreme Clear (penetrating oil) |
| Finish Type | Oil-based, non-film-forming |
| Color | Deep, rich chocolate brown; consistent through full board thickness (not a surface stain) |
| Weathering | Silvers to gray patina over time if not maintained with colortone |
| Durability Class | Class 1 ("very durable") per EN 350 |
| Janka Hardness | ~820–1,325 lbf |
| Dimensional Stability | Radial shrinkage ~0.1–1.0%; tangential ~0.4–1.0% — significantly improved vs. untreated ash |
| Density | ~554 kg/m³ post-modification (roughly 12–20% lighter than untreated ash) |
| Equilibrium Moisture Content | ~4–6% (vs. 18–22% for untreated ash) |
| Water Absorption | Reduced 60–70% vs. untreated ash |
| Service Life | 25+ years in exterior applications with proper maintenance |
| Fire Rating | Class B/C flame spread achievable (ASTM E84) |
| Applications | Exterior siding, cladding, soffits, porch ceilings, feature walls, decking, trim, high-end architectural millwork |
| Fixings | Stainless steel recommended; pre-drilling advised near board ends |
| Maintenance | Clean and re-oil with Cutek Extreme as needed — no sanding or stripping required |
| Sustainability | Domestic hardwood from sustainably managed forests; chemical-free modification; sustainable alternative to tropical hardwoods |
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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.