The bulletproof plant undergoing high-velocity growth

October 17, 2023 12:23 AM

The bulletproof plant undergoing high-velocity growth. Hemp is one of the toughest plants on the planet and its potential uses range from bulletproof vests in the US to waterproof flooring for housing and other robust building products in Australia.
posted by chariot pulled by cassowaries (25 comments total)

Speaking from personal experience, I’m a big fan of hemp in home building. The material itself is great, the plant is a huge carbon sink and that means most houses built with it end up capturing more CO2 than is produced in their construction.

Hemp fibre batts instead of fiberglass is easy to handle and has kept my shed warm through the damp winters.

Hempcrete is an amazing material and after having a chance to stay in a proof of concept building here in Northern Ireland, it’s what I’d use to build a house out of if I ever had the luxury to do that. A great example of what can be done are the projects by Will Stanwix. He learned from the builder of the cottage I stayed in and has a ton of practical experience working with a bunch of different materials.
posted by mrzarquon at 4:51 AM on October 17, 2023 [9 favorites]

It is kind of a shock reading FUD about cannabis / hemp, or the equivalent hemp-isn't-cannabis false distinction that wastes several paragraphs in the article. Toronto is still as uptight as it was before legalization, it's just slightly sweeter smelling.
posted by seanmpuckett at 5:35 AM on October 17, 2023 [2 favorites]

It is kind of a shock reading FUD about cannabis / hemp

Yeah, it’s frustrating over here in Ireland (North and South) where hemp growing and CBD oil are still grey areas. In the North to grow hemp you still need an exceedingly difficult medical research like permit, but spreading industrial fertilizers is A-OK even if it makes the largest lake in the country deadly with cyanobacteria.

Hemp could be an amazing resource to use as part of watershed restoration helping break up soils before native wild forests could take hold and using the crop to build housing (also for clothes, hemp feed, etc.). That and re-introducing wolves could do wonders here (now I’m imagining a “Wolves & Weed for Watersheds” campaign slogan).
posted by mrzarquon at 6:04 AM on October 17, 2023 [11 favorites]

It’s every 2am smoked out dorm room conversation come to life.
posted by Tell Me No Lies at 6:24 AM on October 17, 2023 [5 favorites]

Around here it feels like all the hemp-as-miracle-material arguments disappeared as soon as cannabis became legal. There's a pot shop (usually with an empty parking lot) on every corner and you can get various CBD-infused products everywhere from the local CVS to the sketchy kiosk at the mall, but I wouldn't know where to get hemp-based products or even if they're available.
posted by RonButNotStupid at 6:38 AM on October 17, 2023 [8 favorites]

RonButNotStupid could be describing Tulsa, where I live: we have the highest per capita concentrations of medical marijuana cards and the highest per capita numbers of weed dispensaries in the nation (or we did recently—I haven't checked that info in six months or so).

But not a peep about how we could grow hemp in Oklahoma, a major ag state.

Plus ça change, I suppose.
posted by ivanthenotsoterrible at 7:24 AM on October 17, 2023 [4 favorites]

Around here it feels like all the hemp-as-miracle-material arguments disappeared as soon as cannabis became legal.

Same here. I've been reading/hearing arguments for hemp as the solution to all kinds of problems for decades, but that seems to have really tapered off in the past years.
posted by Dip Flash at 7:41 AM on October 17, 2023 [5 favorites]

This is a capitalism thing, right? Like, an acre of industrial hemp isn't gonna get you the same return (at this point) than an acre of hemp for smoking (they're different, right? I'm pretty sure they're different). Mostly cause the infrastructure to make industrial hemp profitable isn't there, whereas smokable hemp is. Could be totally wrong though.
posted by snwod at 7:46 AM on October 17, 2023 [2 favorites]

...the plant is a huge carbon sink

Well... *cough!* *cough!* ...sometimes, maybe. And don't get me started on those hempcrete gummies. Also, imagine the crimson stitching on the bloodshot eyes of the Wolves on Weed for Watersheds shoulder patches, mrzarquon.
posted by y2karl at 7:50 AM on October 17, 2023 [6 favorites]

Ok it’s not like growing hemp is like growing corn or wheat. It’s not open season. Frex in Canada you need a license to grow industrial hemp and there’s loads of regulations on it. Sucks, right. Just because you can buy weed at CVS doesn’t mean you can buy hemp seeds at you local farm coop and go wild. Also as the article says there’s equipment issues where hemp is very difficult to harvest and process. And the lack of readymade demand. Markets for new raw materials don’t appear overnight especially when retooling is needed.

So the right assessment of the success of industrial hemp is tonnage grown over time, and that seems to be expanding at a 15-20% annual rate, which is pretty amazing.
posted by seanmpuckett at 8:06 AM on October 17, 2023 [6 favorites]

Around here it feels like all the hemp-as-miracle-material arguments disappeared as soon as cannabis became legal.

It probably doesn't help that a certain segment of the Legalize It! crowd deliberately muddied the waters between hemp and cannabis, extolling the virtues of the former in an attempt at providing more legitimacy for the latter.

It was especially odd here in Canada where, as far as I know, industrial hemp was never outlawed like it was in some other countries. So the weird "Hemp is good, man, so also make weed legal" argument never made much sense, since the legal status of one had nothing to do with the other.
posted by asnider at 8:08 AM on October 17, 2023 [3 favorites]

since the legal status of one had nothing to do with the other

To expand on my own comment: I'm oversimplifying here. Industrial hemp is heavily regulated and you need special licenses to grow it, probably due to concerns about people growing cannabis instead. This didn't change after cannabis legalization, because that industry is still highly regulated and tightly controlled in terms of who is allowed to be a licensed producer, etc.
posted by asnider at 8:10 AM on October 17, 2023 [1 favorite]

Yeah, the group of people who promote hemp for various commercial uses shrinks dramatically when the people who mainly just want to get high legally are weeded out.
posted by pracowity at 8:45 AM on October 17, 2023 [1 favorite]

With respect to the "gee there's not much action on the industrial hemp front in legalization States," a couple of things:

1. The Feds still have not gotten off their asses and changed the legal status quo. In their eyes weed is weed, and you can't legally grow weed. Not growing whole fields of it, the way fiber crop farmers would have to, with borrowed money and all that. There's enough money in the pharmaceutical variety that people can put up with doing business in cash and all that, but when you need to grow and harvest tons of plant matter for a crop, and have there be a legal market for it with a price that you can take to the bank to talk about loans...

2. If you clicked through to TFA, you would see a picture captioned

At Wentworth in New South Wales, Gavin Hopkins has adapted a massive 510-horsepower harvester fitted with tungsten steel blades, to harvest his industrial hemp crop.

That is, you don't just add a hemp step to your corn-soybeans rotation without some significant adjustments and investments. I mean, we are talking about a plant whose fiber is talked about as a replacement for Kevlar. See also point #1, you'll probably want to finance the purchase of that special harvester.

3. It is true that there were a lot of people who didn't give a shit about industrial hemp, who talked it up or gave talkers a platform, as long as that could help lend credibility to the anti-prohibition cause. Prohibition is a bad thing, and I cannot get too exercised about whether the end justified the means in this particular case.
posted by Aardvark Cheeselog at 9:29 AM on October 17, 2023 [6 favorites]

the infrastructure to make industrial hemp profitable isn't there

AIUI lots of the world doesnt have or has lost the infrastructure to make best use even of linen, hemp’s slightly less tough and vastly more legal cousin. Long fibers are harder to process than short.
posted by clew at 9:57 AM on October 17, 2023 [2 favorites]

mrzarquon, how do hemp batts do if you ever have a damp intrusion problem?
posted by clew at 9:59 AM on October 17, 2023

Hemp for Victory
posted by hortense at 2:47 PM on October 17, 2023 [1 favorite]

I thought that the barrier to industrial scale hemp cultivation was that the fiber extraction process depends on basically soaking the stalks in water until they just start to rot. Not very amenable to factory automation.
posted by anthill at 6:58 PM on October 17, 2023 [1 favorite]

...when the people who mainly just want to get high legally are weeded out.

I see what you did there.
posted by Thorzdad at 8:41 PM on October 17, 2023 [1 favorite]

Hemp as a building material has been around for a long time and is more than just a guy in a parka at a farmers market talking about the evils of Monsanto. It's frustrating because there are real companies and businesses proving successful and efficient home designs with the material. In Ireland it's particularly frustrating because it's a proven and useful building material but we can't grow it domestically and instead have to import it from mainland Europe. Even with the carbon cost of transporting the material, it's still net negative due to how much carbon is sequestered in the material and how energy efficient it is to build with it (you don't need massive cement trucks or complicated pouring equipment).

Note: the below links are all to actual commercial vendors that provide fire code information and relevant tech data sheets for building and engineering safety purposes.

IsoHemp is probably the leading manufacturer of premade hempcrete blocks, which helps alleviate one of the more common issues with hempcrete construction: drying time. Having precast blocks means that the exterior skin can go up quickly and the interior filled with the traditional formed hempcrete. This process leads to a minimal thermal bridging (you have a continuous layer of hempcrete for the interior) while having a cured exterior surface to finish and make the home water tight.

clew my shed uses Hemp/Jute combination that is treated (so not 100% green). It's rated for mold resistance and there is a vapor barrier only over one side of it, allowing for any moisture that does get in to also leave. Compared to fiberglass or rock wool insulation it was much easier to handle. In the states Hempitecture is a manufacturer of similar material and appears to make them in a wider range of applications.

Hempcretes lack of adoption is now more about making it common knowledge and it would be nice if local governments that are struggling to build greenhousing (or housing at all) would invest in something that could achieve multiple positive benefits. Tom Woolley is the architect behind the Hemp Cottage and has written extensively about the process and science behind it. The cottage itself was built as a proof of concept to get building permission from Northern Ireland housing groups and has made it possible for others to build with it as a result.

Grand Designs featured a house built it with it a few times (and Kevin McCloud is a big advocate of it in general), this is one building. Here is another house (Will Stanwix consulted on the building of this one). BBC just published an article on that second house.

This is an area I've genuinely considered switching careers to work in and focus on. Ireland currently has a massive housing shortage, including thousands of houses that were built with substandard materials that need to be replaced. There are other economic reasons for the shortage (vacant, hedge fund landlords squatting on apartments for one), but building more concrete houses that are either inefficient or require massive amounts of petroleum products to make energy efficient doesn't help in the long term. (The double edged sword of the Mica issue is that trying to convince people to replace their house with an 'unknown' to them material might be another PR challenge).

Part of the problem is lack of demand locally for houses built with it, because it is expensive due to having to be imported and there aren't a lot of builders who know how to work with it. Funding local production (including removing regulation hurdles around growing it) helps put the thumb on the scale for cheaper hempcrete buildings, which would also incentivize builders to become familiar with it, etc. etc. It's particularly popular already for self builds and co-housing projects (where neighborhoods self build their own house) because it's easily scaled up with low skilled manual labor vs complicated SIP or wood frame construction methods. Getting a group of people to pack hempcrete into walls for a few weeks is easy to do. But self builds and co-housing led projects are only a fraction of homes being built at the moment, so finding ways for larger development firms to adopt means getting the checkbooks to balance out also.
posted by mrzarquon at 2:03 AM on October 18, 2023 [6 favorites]

Thank you mrzarquon that was incredibly useful!

I am worried by the combination of novel-ish building techniques and low-cost and semi-amateur building because I knew a bunch of people in the 80s and 90s dealing with 70s builds that weren’t panning out. Like, holes in the walls not panning out. BUT currently completely conventional buildings are cutting corners enough to do that too, so we might as well try something better.

Also the US building code is, I think, too standardized wrt different environments, so I really appreciate pointers into techniques developed in climates like my own.
posted by clew at 11:17 AM on October 19, 2023

I lived in the PacNW for 15 years before I moved to Ireland, so I know the climate and damp concerns of which you speak. The first time I visited the Hemp Cottage was during a cold dark and damp Irish February but the interior was warm and comfortable. I was surprised to learn that it didn’t have fancy, argon filled, triple glazed windows - making the fact that it stayed warm with it’s very high ceilings in the kitchen/dining/living area all the more amazing. A foot thick wall of hempcrete provides plenty of thermal mass to keep a space warm while its lime binder acts as a natural humidity regulator.

The Hempcrete Book by Will Stanwix and Natural Building Techniques by Tom Woolley are great references into the practical design and some of the science between how those spaces work. The hempcrete book covers some of the horror stories from early adopters who went entirely DIY without any training - one of the reasons they wrote the book really. Hempcrete as a material came about from building conservation engineers - old buildings were meant to breath and prevented rot (and damp) by ensuring there was adequate airflow to keep moisture from collecting. Reinforcing those buildings with portland cement (such as repointing brick walls originally made with lime mortar) or using spray foam insulation that everyone loves in new builds, only caused those buildings to fail even faster (and triggering rising damp and black mold). The result is hempcrete has probably undergone more scrutiny for longevity and healthiness because it was used with an eye towards the sustainability of the space and not just solving the short term problem of “water comes in here / hot air leaves through this crack”.
posted by mrzarquon at 2:13 AM on October 20, 2023

how do hemp batts do if you ever have a damp intrusion problem?

Moisture generally has to be kept out of any building but wood framed buildings especially. Cellulose insulation, mostly in ceilings but also in walls, is widely used for insulation and it has all the moisture resistance of a piece of paper because it is essentially just ground up paper. Boric acid is added to the milled paper for mold and pest resistance.
posted by Mitheral at 9:24 AM on October 20, 2023 [1 favorite]

Cellulose insulation, mostly in ceilings but also in walls

Hemp is not like cellulose wood pulp insulation (which I used when I lived stateside). While the fiber batts in my shed are treated with a soda like compound (probably something similar to boric acid), hemp itself is hydrophobic (one of the many reasons its been used as rope on sailing ships for centuries) so it's not going to act like the moisture sponge that cellulose does. If there's a place for the moisture vapor to go, it will evaporate / dry out on the rare chance water gets into it. For reference this is what the interior of my shed looked like before I put the vapor barrier up.

Hemp fiber batt insulation is also an entirely different material than hempcrete, the fiber batt is a great drop in replacement for pink fiberglass, expanded foam board, or rock wool in many situations. Hempcrete is more a complete "we need to build a new wall" however people do use it for retrofit insulation over masonry buildings (or insulating interiors of historic brick buildings).
posted by mrzarquon at 9:54 AM on October 22, 2023 [1 favorite]

Sorry wasn't trying to make an equivalency, just noting that keeping insulation dry is already a concern with known solutions. No wall or roof insulation should be getting wet because that is a serious problem for the entire building even if the insulation would handle it
posted by Mitheral at 1:24 PM on October 22, 2023 [1 favorite]