Materials · Solid woodbeginner~2 min read

Softwoods: pine, cedar, fir and redwood

Short answer

Softwoods cut easily and finish badly. The problem is not hardness, it is that the soft spring wood and hard summer wood in each growth ring cut differently, so edges fuzz and detail crumbles. Sharp tools, downcut bits and light finishing passes are the answer.

The thing that makes softwood tricky

Every growth ring in a softwood has two parts: light coloured early wood that grew fast and is soft, and dark late wood that grew slowly and is much harder. The density difference between them is far larger than in most hardwoods.

A cutting edge crossing that boundary meets a sudden change in resistance. The soft part compresses and tears rather than shearing cleanly, and the hard part cuts fine. The result is an edge that alternates between crisp and fuzzy, which is why a V-carved letter in pine can look sharp in one stroke and ragged in the next.

Species notes

Pine

Cheap and everywhere. Resinous, knotty, fuzzy. Good for learning and painted work.

Cedar

Aromatic, weather resistant, very soft. Dust is a known respiratory sensitiser.

Douglas fir

Stronger, very pronounced ring contrast, tears out readily

Redwood

Soft, stable outdoors, expensive, fragile detail

Resin and knots

Resin builds up on the bit. A gummy bit cuts badly and burns. Clean bits with a resin remover, not by scraping, which damages the edge.
Knots are much harder than the wood around them. The tool hits one, deflects, and often leaves a visible step. Design around knots where you can, or embrace them.
Pitch pockets can be liquid inside. They will make a mess of a finish and sometimes of your spoilboard.

Getting a clean result anyway

Use a sharp bit. More important here than in hardwood, because a dull edge compresses soft fibres rather than cutting them.
Downcut for the top surface. It presses fibres down while cutting, which is exactly the problem softwood has.
Take a light finishing pass. Leaving about 0.02 inches and cleaning it up at full depth removes most of the fuzz.
Do not slow down. A slow feed compresses rather than cuts. Keep the chipload real.
Sand before finishing, then again after the first coat. The first coat raises the remaining fuzz so you can cut it off.
Consider a sanding sealer on anything that will be stained, because softwood absorbs stain unevenly and blotches.

Construction lumber is worth testing

A kiln dried 2x10 from the lumber yard can be genuinely good material for signs once it acclimates, and it costs a fraction of hardwood. It is also wet, twisted and full of stress when you buy it. Buy it, sticker it in the shop for a few weeks, then flatten it before you machine anything that needs to stay flat.

Moisture, the hidden variable

Construction softwood is often sold at a much higher moisture content than furniture hardwood. Wet wood gums the bit, cuts fuzzy, and moves after you cut it. A piece that was flat on the machine can cup within a week in a heated shop. If the finished piece needs to stay flat, dry it first and machine it second. See wood movement.