6 ms·

New lubricated mussel-proof coating

90 points by tribonet 9y ago

SeanDav 9y ago
> "Large accumulations of mussels can weigh as much as 1,700 pounds per square foot." I really find it hard to believe that is a number based in reality. Disclaimer: I am no expert! EDIT: Even if the mussels were solid gold and it was a cubic foot of them, they would "only" weigh 1206 pounds. source: http://www.coolmagnetman.com/magconda.htm http://www.coolmagnetman.com/magconda.htm
- blacksmith_tb 9y ago
  A little digging around suggests 35kg per square meter is a more reasonable estimate[1], which is about 8lbs per sqft. I suppose it's possible some measures include the weight of the water in the mussels, and others don't? 1: https://www.boatdesign.net/threads/boat-weight-increase-due-to-the-marine-growth.48041/ https://www.boatdesign.net/threads/boat-weight-increase-due-...
  - Retric 9y ago
    That's ignoring the buoyancy from displacing water and only covers two years. I could see the worst case say a stationary house boat being vastly more problematic over 30+ years. But, they should generally fall off before the weight gets crazy.
- mjlangiii 9y ago
  I just assumed cubic feet
  - kimolas 9y ago
    Even a cubic foot of water would be well under 100lbs. I doubt a cubic foot of mussels + water to fill the rest could weigh a ton. It may be possible for (especially stationary structures) to accumulate enormous columns of biofouling materials, but for such a layer to reach > 20 feet thick (possibly closer to 50 feet without counting the interstitial water) sounds unreasonable. But I'm not knowledgable in this area.
- notatoad 9y ago
  It does seem hard to believe, perhaps they mean a square foot of mussels on a boat bottom causes drag equivalent to towing an extra 1700lbs?
- ChuckMcM 9y ago
  I'm guessing it is a typo of some form. One (or perhaps both) of the unit values are wrong. It doesn't takeaway from the fact that mussels are a huge issue, or the amazing way they have adapted to attaching themselves to surfaces.
- pishpash 9y ago
  Find a way to harvest the mussels and you'll need no food delivery at sea. /s
- dguaraglia 9y ago
  I wonder if the author is confusing weight with drag. I could see mussels (and the algae they always bring with them) introducing more drag on the hull than their weight. But then again, I'm no expert, just a weekend sailor.
- jandrese 9y ago
  I had a mental image of a foot square patch of hull with a 200m long spire of mussels sticking off the side. I'm pretty sure that's a typo in the article.
  - gozur88 9y ago
    "It's weird. The chart says depth here is 200m, but we always bottom out." Yeah, that's just a crazy number. It would be a crazy number if mussels were made of lead.
- clort 9y ago
  perhaps the square foot is only the footprint of the accumulation of mussels? They could extend out a pretty long way..
CalChris 9y ago
This sort of anti-fouling is the holy grail. Copper based anti-fouling goes back centuries. The USS Constitution was copper bottomed in 1794. https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/ https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/ I remember an NPR story about using extremely hot peppers (adding capsaicin to bottom paint) to defoul. There was an anti-stick bottom paint but the trouble with it was that it wouldn't stick to hull. The trouble with copper is that it's a biocide, it kills. You're basically putting poison on the bottom of your bottom which leaches into the soil. Like tributyltin, copper's days are numbered. It's a hard problem. When I get back into sailing, it'll be dry sailing (put boat in water and haul out when done). BTW, bottom jobs are freaky expensive, $10,000 for a race bottom every year.
- jerf 9y ago
  "Copper = poison" is an oversimplification. Copper is also an important mineral, with 2mg/day a rough guideline for human consumption: https://ods.od.nih.gov/News/Copper.aspx https://ods.od.nih.gov/News/Copper.aspx (That number is at the very end, and that link also contains other interesting details about it.) It's not like lead, where basically every atom of it in you or the ecosystem is doing no good.
  - derefr 9y ago
    That's humans. Are lower animals (and plants, and bacteria) the same, or is copper more like lead to them?
    - jerf 9y ago
      Well, considering our bodies all eventually end up feeding lower animals, plants, and bacteria, it can't be that fatal to them. Edit: If you want way too much detail in answer to your question: http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Environment.pdf http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Enviro... The most relevant bit is probably this bit on the bottom of page 5 and into page 6: "A study was performed to determine if pen-raised salmon were bioaccumulating copper from the antifouling coatings on the pens (20). Five pens were used - three of which were treated with cuprous oxide containing antifouling coatings and the other two were left untreated. The concentrations of copper in the muscle and liver of the salmon were measured, Figure 7. It was found that there was no correlation to pen treatments. It was speculated that the reason for this is the leaching of the copper was sufficiently slow such that the natural homeostasis of the fish and their detoxification processes are not compromised and that the leached Cu ion is reduced by complexation with organic and inorganic substances in the seawater." It isn't clear to me if these "pens" were enclosed or not; if they were then there really doesn't seem to be much reason to worry about copper antifouling. The article also says "Copper is an essential element required for normal growth in all plants and animals. As such, it is considered a normal constituent in the ecosystem in both soil and water where its presence is partially due to the metabolic by-products of plants and animals as previously discussed." The oceanic concentration of copper is given as 0.25ppb, which comes out to 340 million metric tons of copper in the oceans overall. I suspect that, like many do with "radiation", we tend to casually assume the normal concentration in the world is zero, thus rendering any human addition to the world an infinite-percent increase, but the natural world is messier than that. I thank you for your question, the research was interesting.
delafuentecaro 9y ago
I never thought I would see the day ;)
exabrial 9y ago
Barely anything sticks to HDPE, has that ever been tested?
- hwillis 9y ago
  HDPE and PTFE (teflon) both have very interesting self-lubricating qualities; their surfaces act almost like they are somewhat liquid, not unlike ice. They're not nearly as good as SLIPS but they have similar properties. I don't know if it's true but the way I've heard it explained is that PTFE and HDPE are so long-chained that loose molecule ends act kind of like hairs on the surface. The hairs can slip over each other very easily, so they act somewhat like a liquid. But in reality HDPE is specifically used to grow mussels on: http://www.plasticsnewseurope.com/article/20131011/PNE/310119980/hdpe-platforms-used-for-mussels-farming http://www.plasticsnewseurope.com/article/20131011/PNE/31011...
  - mickronome 9y ago
    Isn't the HDPE only used as flotation devices to hang culture ropes from ? If not, I've got another project I'll never do: Figure out how mussels adheres to HDPE and make revolutionary paints and glues for it!
    - owenversteeg 9y ago
      Mussels use byssus threads, which are a keratin+polyphenolic protein core coated in an adhesive protein mix. The keratin/polyphenolic core provides the strong part, then the adhesive obviously adheres it. Both parts are very important, and I imagine it'd be hard to have the adhesive work well by itself. The process of creating the threads also seems relatively difficult, but Google seems to have some byssus-based adhesives. Who knows, maybe you'll end up with something interesting. Particularly this, seems like it might not be too difficult to make at home with some equipment and knowledge: https://www.livescience.com/6974-glue-derived-clinging-mussels.html https://www.livescience.com/6974-glue-derived-clinging-musse...
FabHK 9y ago
Paper: http://science.sciencemag.org/content/357/6352/668 http://science.sciencemag.org/content/357/6352/668 DOI: 10.1126/science.aai8977 It doesn't seem to contain the 1700 lbs per square foot number (it just mentions pull-off energy in the order of 1J/m^2). And linked article, originally hosted at harvard.edu (what's with these websites just copying articles and hosting them themselves??): https://news.harvard.edu/gazette/story/2017/08/wyss-developed-antifouling-coating-a-boon-to-business-and-environment/ https://news.harvard.edu/gazette/story/2017/08/wyss-develope...
carapace 9y ago
(Unrelated, to hell with those popups that trigger when your mouse leaves the window. To hell with them I say!)

90 points by tribonet 9y ago

> "Large accumulations of mussels can weigh as much as 1,700 pounds per square foot." I really find it hard to believe that is a number based in reality. Disclaimer: I am no expert! EDIT: Even if the mussels were solid gold and it was a cubic foot of them, they would "only" weigh 1206 pounds. source: http://www.coolmagnetman.com/magconda.htm http://www.coolmagnetman.com/magconda.htm

blacksmith_tb 9y ago
A little digging around suggests 35kg per square meter is a more reasonable estimate[1], which is about 8lbs per sqft. I suppose it's possible some measures include the weight of the water in the mussels, and others don't? 1: https://www.boatdesign.net/threads/boat-weight-increase-due-to-the-marine-growth.48041/ https://www.boatdesign.net/threads/boat-weight-increase-due-...
- Retric 9y ago
  That's ignoring the buoyancy from displacing water and only covers two years. I could see the worst case say a stationary house boat being vastly more problematic over 30+ years. But, they should generally fall off before the weight gets crazy.
mjlangiii 9y ago
I just assumed cubic feet
- kimolas 9y ago
  Even a cubic foot of water would be well under 100lbs. I doubt a cubic foot of mussels + water to fill the rest could weigh a ton. It may be possible for (especially stationary structures) to accumulate enormous columns of biofouling materials, but for such a layer to reach > 20 feet thick (possibly closer to 50 feet without counting the interstitial water) sounds unreasonable. But I'm not knowledgable in this area.
notatoad 9y ago
It does seem hard to believe, perhaps they mean a square foot of mussels on a boat bottom causes drag equivalent to towing an extra 1700lbs?
ChuckMcM 9y ago
I'm guessing it is a typo of some form. One (or perhaps both) of the unit values are wrong. It doesn't takeaway from the fact that mussels are a huge issue, or the amazing way they have adapted to attaching themselves to surfaces.
pishpash 9y ago
Find a way to harvest the mussels and you'll need no food delivery at sea. /s
dguaraglia 9y ago
I wonder if the author is confusing weight with drag. I could see mussels (and the algae they always bring with them) introducing more drag on the hull than their weight. But then again, I'm no expert, just a weekend sailor.
jandrese 9y ago
I had a mental image of a foot square patch of hull with a 200m long spire of mussels sticking off the side. I'm pretty sure that's a typo in the article.
- gozur88 9y ago
  "It's weird. The chart says depth here is 200m, but we always bottom out." Yeah, that's just a crazy number. It would be a crazy number if mussels were made of lead.
clort 9y ago
perhaps the square foot is only the footprint of the accumulation of mussels? They could extend out a pretty long way..

CalChris 9y ago

This sort of anti-fouling is the holy grail. Copper based anti-fouling goes back centuries. The USS Constitution was copper bottomed in 1794. https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/ https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/ I remember an NPR story about using extremely hot peppers (adding capsaicin to bottom paint) to defoul. There was an anti-stick bottom paint but the trouble with it was that it wouldn't stick to hull. The trouble with copper is that it's a biocide, it kills. You're basically putting poison on the bottom of your bottom which leaches into the soil. Like tributyltin, copper's days are numbered. It's a hard problem. When I get back into sailing, it'll be dry sailing (put boat in water and haul out when done). BTW, bottom jobs are freaky expensive, $10,000 for a race bottom every year.

jerf 9y ago
"Copper = poison" is an oversimplification. Copper is also an important mineral, with 2mg/day a rough guideline for human consumption: https://ods.od.nih.gov/News/Copper.aspx https://ods.od.nih.gov/News/Copper.aspx (That number is at the very end, and that link also contains other interesting details about it.) It's not like lead, where basically every atom of it in you or the ecosystem is doing no good.
- derefr 9y ago
  That's humans. Are lower animals (and plants, and bacteria) the same, or is copper more like lead to them?
  - jerf 9y ago
    Well, considering our bodies all eventually end up feeding lower animals, plants, and bacteria, it can't be that fatal to them. Edit: If you want way too much detail in answer to your question: http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Environment.pdf http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Enviro... The most relevant bit is probably this bit on the bottom of page 5 and into page 6: "A study was performed to determine if pen-raised salmon were bioaccumulating copper from the antifouling coatings on the pens (20). Five pens were used - three of which were treated with cuprous oxide containing antifouling coatings and the other two were left untreated. The concentrations of copper in the muscle and liver of the salmon were measured, Figure 7. It was found that there was no correlation to pen treatments. It was speculated that the reason for this is the leaching of the copper was sufficiently slow such that the natural homeostasis of the fish and their detoxification processes are not compromised and that the leached Cu ion is reduced by complexation with organic and inorganic substances in the seawater." It isn't clear to me if these "pens" were enclosed or not; if they were then there really doesn't seem to be much reason to worry about copper antifouling. The article also says "Copper is an essential element required for normal growth in all plants and animals. As such, it is considered a normal constituent in the ecosystem in both soil and water where its presence is partially due to the metabolic by-products of plants and animals as previously discussed." The oceanic concentration of copper is given as 0.25ppb, which comes out to 340 million metric tons of copper in the oceans overall. I suspect that, like many do with "radiation", we tend to casually assume the normal concentration in the world is zero, thus rendering any human addition to the world an infinite-percent increase, but the natural world is messier than that. I thank you for your question, the research was interesting.

delafuentecaro 9y ago

I never thought I would see the day ;)

exabrial 9y ago

Barely anything sticks to HDPE, has that ever been tested?

hwillis 9y ago
HDPE and PTFE (teflon) both have very interesting self-lubricating qualities; their surfaces act almost like they are somewhat liquid, not unlike ice. They're not nearly as good as SLIPS but they have similar properties. I don't know if it's true but the way I've heard it explained is that PTFE and HDPE are so long-chained that loose molecule ends act kind of like hairs on the surface. The hairs can slip over each other very easily, so they act somewhat like a liquid. But in reality HDPE is specifically used to grow mussels on: http://www.plasticsnewseurope.com/article/20131011/PNE/310119980/hdpe-platforms-used-for-mussels-farming http://www.plasticsnewseurope.com/article/20131011/PNE/31011...
- mickronome 9y ago
  Isn't the HDPE only used as flotation devices to hang culture ropes from ? If not, I've got another project I'll never do: Figure out how mussels adheres to HDPE and make revolutionary paints and glues for it!
  - owenversteeg 9y ago
    Mussels use byssus threads, which are a keratin+polyphenolic protein core coated in an adhesive protein mix. The keratin/polyphenolic core provides the strong part, then the adhesive obviously adheres it. Both parts are very important, and I imagine it'd be hard to have the adhesive work well by itself. The process of creating the threads also seems relatively difficult, but Google seems to have some byssus-based adhesives. Who knows, maybe you'll end up with something interesting. Particularly this, seems like it might not be too difficult to make at home with some equipment and knowledge: https://www.livescience.com/6974-glue-derived-clinging-mussels.html https://www.livescience.com/6974-glue-derived-clinging-musse...

FabHK 9y ago

Paper: http://science.sciencemag.org/content/357/6352/668 http://science.sciencemag.org/content/357/6352/668 DOI: 10.1126/science.aai8977 It doesn't seem to contain the 1700 lbs per square foot number (it just mentions pull-off energy in the order of 1J/m^2). And linked article, originally hosted at harvard.edu (what's with these websites just copying articles and hosting them themselves??): https://news.harvard.edu/gazette/story/2017/08/wyss-developed-antifouling-coating-a-boon-to-business-and-environment/ https://news.harvard.edu/gazette/story/2017/08/wyss-develope...

carapace 9y ago

(Unrelated, to hell with those popups that trigger when your mouse leaves the window. To hell with them I say!)