[peter422]

This chair is made from pressure treated wood. Technically speaking, it is safe to sit on, but personally I'd like to avoid those chemicals against my skin if I could. Regular lumber probably would be preferable, especially when it would take $10 and 20 minutes to replace it after 5 years when it has rotted (or you could spring for redwood or cedar for an extra $10 and double or triple the life of your chair).

[jdhendrickson]

Most pressure treated lumber eschews the old arsenic method. Most only have copper and an anti fungal (Tebuconazole) in it. Perfectly safe for an outdoor chair.

[Bluestrike2]

The problem with using modern pressure treated wood for outdoor furniture is less any cancer risks like with the old CCA treatments, and more that it's just a bad choice for a bunch of different reasons.

Modern copper-based treatments--e.g. ACQ or CA--still cause skin and eye irritation. If you try to sand it so that people sitting in your new chair don't get a nasty splinter somewhere best avoided, you can compromise the effectiveness of the treatment (even when the treatment gets full penetration, it's still most effective on the outer layers you're now sanding away). Plus, while the dust you create when working with it might not include arsenic, it's still nasty to breathe in and can cause respiratory problems. Staining P/T wood can be a whole ordeal in itself, and because interact much more closely with furniture than say a deck, any imperfections will be more noticeable.

Even then, it's not like P/T furniture isn't going to require ongoing maintenance in the future. At which point, you're better off with something like cedar or white oak. Hell, with a decent outdoor grade finish and proper care, even untreated pine is going to last for years without rotting away underneath you.

[b112]

You can buy normal wood, then apply treatments afterwards, then stain or what not.

Still trouble when the chair is at end of life, and you burn or bury it.

[foobarian]

With a product this simple to make and prices of wood and finishing chemicals what they are I don't know if I'd even bother with finishing, but just remake.

[dcrazy]

In many parts of the world, an untreated wood outdoor chair would only survive a season or two before atmospheric moisture ruined it.

[euroderf]

Basic weatherproofing treatments for basic lumber ? There's tar, which nobody does at home. There's wood oil. What else is there ? Do I have other options ?

[harrall]

Varnish like polyutherane.

Here’s what I use for furniture that I build:

- My planters use red cedar, often bare.

- My outdoor furniture use a wood oil plus polyutherane.

- My indoor furniture use just wood oil.

But that’s only in general. There are other considerations like impact resistance and spills that can stain the wood so you have to decide what combination of wood type and treatments work for your goal.

[euroderf]

"wood oil plus polyurethane" sounds interesting. NSo you've had no problems with the two reacting badly to each other ? I'll be drilling screws in, so maybe the wood oil adds extra protection where screws penetrate the polyurethane layer.

[bArray]

We used to treat wood with oil (literally from kitchen oil to motor oil). Apparently the Japanese burn theirs to treat it [1]. I don't think you have to leave it to rot out.

[1] https://www.instructables.com/How-to-Burn-Stain-Wood-Aka-Sho...

[0xbadcafebee]

Keep in mind Yakisugi ("shou sugi ban" is a Western misinterpretation circa ~1995) is traditionally performed on wood which is already weather resistant, particularly Japanese Cedar ("sugi" is cryptomeria japonica, a type of cypress endemic to Japan). Even then they still treat it with oil regularly to improve its longevity. So I wouldn't char some white pine and stick it outside and expect it to last.

[harrall]

We still treat wood with oil. Your local home improvement store should stock a bunch and you’ll find more at a woodworking store.

You can also add a sealant on top like polyutherane if you want it to last even longer at the cost of imparting a different texture.

[asdefghyk]

RE ...pressure treated wood.... In my country such timber is banned in certain situations - for example children's playgrounds ...

[mbrock]

I'd rather have my kids play on pressure treated timber than rotting timber...

[adrianN]

Fortunately those are not the only two options.

[foobarian]

Right, just look at our local playgrounds: no more wood anywhere in sight, just faux-wood plastic that never rots but just slowly sheds microplastics into the environment

[0_____0]

I'd be less concerned about that than the fact that every car that drives by the playground is shedding pounds of tyre plastic into the air/water as a matter of course. At least the playground materials aren't designed to turn into particulates.

[dingdingdang]

So true.. plus all the "plush" plastic pellet "landings" rather than simply dirt cause oh no: someone may get into contact with some microbes.. gotta keep those allergy numbers rolling. /s

[Cthulhu_]

That's a false dichotomy and I'm sure you can do better.

[sgt]

As a parent you just spend a minute or two inspecting a playground. It's easy to spot something that is rotting.

[keyle]

I'm not familiar with this. What are the dangers?

[steamrolled]

Back in the olden days, pressure-treated wood contained compounds of arsenic and chromium. This made it pretty terrible to cut, sand, burn, etc.

The warnings persist in part because older wood still has that problem, so "reclaimed wood" projects can be risky. That said, since mid-2000s, wood in the US and the EU is treated primarily with much safer copper compounds. Copper isn't hugely toxic to humans at the levels you're likely to be exposed to from wood.

To be fair, the treatment often also includes an organic fungicide (the "azole" part in "copper azole"), which is probably not understood as well as copper.

[Cthulhu_]

That puts me in mind of old railway sleepers being used for garden projects like raised beds and low walls. They were treated with ??? something, in summer the black tar would leech out of them.

[dugmartin]

The are treated with creosote: https://en.wikipedia.org/wiki/Creosote

[motorest]

> I'm not familiar with this. What are the dangers?

Wood is typically treated with nasty chemicals. For example, formaldehyde is extensively used in these applications, and it's linked with cancer.

https://www.cancer.org/cancer/risk-prevention/chemicals/form...

[alwa]

Is formaldehyde used in treating PT lumber? That link suggests it shows up in resins for engineered wood products, like particleboard for interior furniture.

I was of the impression that PT lumber to modern standards involved relatively innocuous copper plus an organic biocide like an azole (for antifungal purposes), no?

And I thought the formaldehyde-heavy resins were regulated into obscurity back in like 2009, were they not?

[0_____0]

A simple urethane or even latex paint would suffice to protect untreated wood from the elements