New process for preserving lumber could offer advantages over pressure treating | Hacker News Reader

New process for preserving lumber could offer advantages over pressure treating

phys.org

23 pointselijahparker9 comments

One advantage they don't discuss is perhaps lack of toxicity. I used to do Carpentry during summer break and sometimes we'd burn scraps for heat. I was advised not to throw treated lumber into the pile as it's toxic so this would be a good step in the right direction towards less toxins introduced into homes and groundwater.

Agreed, but looking at the three substances they mention in the article - Oxides of Zinc, Aluminium and Titanium, I guess there could be other considerations in terms of groundwater issues?

Also, how practical, cost-wise would this be? It's not mentioned in the article, but surely titanium would be prohibitive in terms of cost? (Even for small amounts)

Let's see if I can multiply up the numbers correctly. Please let me know if I'm messing these up.

Article is closed, but supplementary material is free.

Each experiment is 3 blocks of wood, each 5 grams. So 15g of wood.

They say they need 2x10^20 molecules of TiCl4 for one experiment (perhaps the final deposited amount in the extreme 'all cells covered' case). Or 3x10^-4 moles. That's 200x10^-4 or 2x10^-2 for 1kg wood. Making it up to 1 mole gives us 50kg of wood. 1 mole is 190g of TiCl4. Or about 250kg wood per kg TiCl4.

Alibaba costs (I'm not in the field so that's based on it being there first link) puts that at maybe a dollar or two.

Caveats: may require less because completely covering all cells is not realistic. May require more because you don't use things completely efficiently. Alibaba may not be representative (either direction) and the "99.9%" pure stuff there may not be good enough and going higher may get exponentially more expensive.

But it doesn't seem like the raw cost of the materials necessarily would be a problem to me.

Chromated copper arsenate, which is highly toxic, used to be used to make pressure treated wood. Throwing a piece on the fire would have released a good bit of arsenic.

Since 2003 pressure treated wood is made with alkaline copper quanternary, copper azole or micronized copper azole. They are all very much all less toxic since they are believed not be be able to be absorbed by the body, but I still wouldn't throw any on a fire.

The article is credited "by Georgia Institute of Technology", so it is a press release. This is just early research, but presumably the problems of toxicity are what inspired the study in the first place. But, they can't make any claims yet, because lawyers. And cost would be a huge factor, unless regulation were involved. There is a potential public good in reducing toxins in the environment. But what about their idea of using it for framing lumber? Nobody uses pressure treated for framing today, do they? It would help insulate, they say, but there's no way that would make any sense unless the cost were much lower than today's treated lumber, which... well it's just an early research project.

The thing about toxins in treated lumber, it isn't a bug in the product. It is actually the feature. Treated lumber is just as porous and traps water like any other lumber. It has so much copper compounds trapped in it that almost nothing can ever break it down. If you bury treated lumber in the ground you will find it sterilizes a small layer of soil around it. This is why it is so effective.

Anything trying to reduce the toxicity of treated lumber by swapping on a coating runs into the same problem as traditional methods like painting the lumber: a single tiny hole in the coating allows the entire piece of lumber to be compromised.

Why are all of the comparisons to untreated lumber? Shouldn’t they have tested against pressure-treated lumber too to see how well it performs against that?

It depends what you're trying to show. "Does this process change the wood in certain ways" and "does this process change those properties more than other processes" are different questions, and it seems reasonable to start with the former.

I'm not familiar with all types, but most pressure treatments don't attempt to stop water uptake, they just impregnate the wood with pesticides/fungicides.

It's not there to stop the water, it's there to stop termites, fungi, mites and other pests that can degrade or threaten the integrity of wood. That's why most exterior decking should be sitting on something like this (https://www.amazon.com/Simpson-Strong-Tie-ABA44Z-Gauge-20-Pa...) to prevent water uptake.

I'd be curious to see how this compares to treated wood for their mold test, though. That seems like a really valid test.

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