It was my understanding that fast growing or undergrown wood has poor stability against humidity.

Walnut isn't difficult to source because it grows slowly, though it doesn't grow fast; a walnut tree can grow upwards of a foot a year given good conditions. The problem is that most varieties of walnut are scraggly and actually getting decent boards out of them is difficult.

North American Black Walnut, when grown in it's preferred conditions, is anything but scraggly. Getting good, straight timber from it isn't hard, but it does take good soil, rainfall, and time - from nut to harvestable high quality timber takes something on the order of a human lifetime.

Walnut is basically a weed on my farm - I cut down 25 as saplings for every one I leave to grow to maturity - as it's preferred habitat is in colonizing grassy and weedy areas, where it's huge seed, and rapid growth as a young tree, allow it to get ahead of and above weeds, brush, and many other hardwood species.

Getting good straight timber from black walnut (or most walnuts) is absolutely doable (as evidenced by...us doing it for centuries!). At the same time it's more difficult than you're giving it credit for, though--"its preferred conditions" is a really load-bearing statement! It's not just soil and rainfall, though those of course matter a lot--as I understand it the biggest blocker to quality American walnut production is spacing. Those huge walnut trees have space to grow, and walnut trees grown under natural conditions tend to fight for sunlight. When they grow in natural distributions, they do tend to be thinner and have odd kinks in the trunk. Like you say, they're scrub trees. You can make them not be them, but it's work!

Contrast this to other hardwoods like maples or (most) oaks, which don't really care much about being relatively tightly packed. Silviculture is very much about strategizing how to grow trees in effective ways to get the outcomes you describe, and it's pretty fascinating stuff.

Spacing is indeed important, and if you are going to grow walnut on a plantation, you want to manage spacing over the first 20 years of the plantation pretty closely, with very dense competition in the early years to force straight upward growth, followed by thinning to allow space for crowns to gather enough light to maintain growth rates. You don't have to do that with most conifers, which tend to grow straight single boles regardless, but you do with most other North American hardwoods, including timber maples, and most species of oak.

You can't make Ikea-style furniture out of high-quality wood: particle board is FAR higher quality than real wood. Quality is a synonym for consistency (not luxury), and particle board is far more consistent than real wood. Most importantly, particle board is dimensionally stable. This is why even high-end furniture uses a lot of plywood. Real wood has horrible dimensional stability: it warps as humidity levels change. That would never work with Ikea-style furniture.

If you wanted to make Ikea-style furniture with higher-end materials than particle-board, you'd use Baltic Birch plywood, and certainly not solid Walnut.

I think you mean plywood, not particle board. Very different things. Particle board is crap.

You can also construct with hardwoods in a way that prevents warping and cupping, like using rift sawn cuts and orthogonal grain joiniery. It’s not some secret, this is taught in woodworking 101.

I’ve built a lot of my own furniture with hardwoods and none of it has warped in a decade.

>You can also construct with hardwoods in a way that prevents warping and cupping, like using rift sawn cuts and orthogonal grain joiniery.

No, you can't. Not if you're making IKEA furniture that customers assemble themselves.

>I think you mean plywood, not particle board. Very different things. Particle board is crap.

No, it's not, if you're making inexpensive furniture that customers self-assemble. Good plywood is very expensive.

>I’ve built a lot of my own furniture with hardwoods and none of it has warped in a decade.

Great, let's see you make something that way that ships in a flat box, and which some idiot can put together with pictogram instructions using no tools except a screwdriver for turning cam-lock fasteners.

>Great, let's see you make something that way that ships in a flat box, and which some idiot can put together with pictogram instructions using no tools except a screwdriver for turning cam-lock fasteners.

You've clearly never dealt with old furniture. Tables, chairs and beds used to be and some still are packaged and assembled in this manner. Granted they used threaded inserts instead of cam-lock stuff.

You seem to conflate "good" with "cheap"; particle board is "just" cheap, it's not good.

Plywood will be stronger, lighter, and deal better with humidity, it is "better" as material on pretty much every measure.

Plywood is far more expensive.

Good, cheap, fast: pick any two.

For the price, particle board is good.

IKEA used to ship solid wood products -- and laminated pine-strip items too -- in flat boxes.

Back in the 90s, I bought a solid wood bookshelf and a laminated pine strip coffee table from them. They were structurally sound and very durable. In fact, a couple of years ago, I repurposed the bookshelf to create a built-in.

So it's definitely do-able!

They still do this, fwiw. I have a TARVA dresser in my spare room which came unfinished. I used...probably too-expensive (for what it is) gel stain and lacquer on it and it came out pretty nice for a couple evenings' work.

A fast growing birch tree would be amazing. Baltic birch is an incredible material, I have two torsion box workbenches made of it.

I hate this sort of Reddit-engineer comment where you redefine a word and then use that redefinition to back up some garbage opinion.

No, particle board is not "high quality". It has inferior mechanical and weathering properties to real wood, chip board and plywood. What particle board is is cheap enough and good enough.

properly done glued wood boards don't have a warping problem, and sometimes are even stronger than whole wooden planks. In fact most of Ikea furniture is made from those, except wardrobes and cupboards, which are not expected to have much pushes from aside.