Phil Pascoe
Established Member
and a dished oilstone.
Grass
- Thread starter baldkev
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stuart
Nah, copper. Best you'd do is make it a bit less blunt, no doubt Jacob will enlighten us all shortly. I am sure it's really quite simple if you think about it, hope that helps 
Jacob
What goes around comes around.
Yes copper apparently. Is it controversial?Nah, copper. Best you'd do is make it a bit less blunt, no doubt Jacob will enlighten us all shortly. I am sure it's really quite simple if you think about it, hope that helps
They didn't use "ice" in stone masonry but they did use a lot of other techniques!
https://factsanddetails.com/world/cat56/sub404/entry-6154.htmlJust read though that link again - it seems the wet wedge theory is probably not true: "A fiction often repeated in the popular archaeological literature is that the wedge holes were cut for wood wedges which, when wetted, would expand and so split the rock. In reality, this cannot work for the sizes and shapes, spacings, and often inclined orientations of wedge holes found in ancient hardstone quarries."
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Jacob
What goes around comes around.
Just found the book! This was the local chap. I guessed he'd popped off I hadn't seen him for a long time. I was supposed to be doing some windows for him too!
https://www.trees.org.uk/News-Blog/Latest-News/Rodney-Helliwell-1940–2018I talked to him a lot a few years ago about tree-root and other damage to buildings. He used to get called out as expert witness in court cases, insurance claims etc.
He said plants often get the blame for damage when in fact the damage came first and the plant has merely invaded the space, sending roots into cracked mortar etc. At the time there was mass hysteria about Japanese knotweed.
I'm pretty sure moss is the same and is unlikely to be the cause of damage; rather it takes off where there are already cracks, absorbent surfaces etc. Take off the moss and some of the already broken stuff comes with it. Given a good surface then the moss can't colonise anyway.
The moss and ice idea doesn't make sense either as bare roofs without moss are subject to more severe levels of snow, ice, variable temperatures.
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Wondering how many millilitres in my petrol can... I've found the differing of OPINIONS very interesting, if a little harsh on Jacob. I have a slate roof, checked a little while ago and was also wondering why the rust on my rubbish tin bike shed wasn't more pronounced under the moss patches; I asked a materials scientist of 34 years. (sorry a bit long, trying to condense what was a fascinating chat and is, of course, only his opinion) Quick background.. various studies into roofing failures and has given evidence more than once in court . I make no claims as to the accuracy of my recollection as I treated him to lunch and there may have been Doom Bar and Timmy Taylor's involved.
He tells me that slate is laid down in thin bedding layers makes it split 'beautifully along the planes of cleavage' (incidentally, not often along the bedding layers). It's these granular layers that allow moisture ingress especially along edges and where nails have caused micro fractures but also on the flat surface and result in exfoliation. He uses ' a tile' to denote any material shaped into a square or rectangle.
Where the edges are - if the bedding layers in on a slight angle you get the little flakes off the edges more readily than if they were laid perfectly flat but as it's granular the upward force will cause a rising crack. Moss spores will generally get rinsed off but these small breaks and gaps allow them to gather and grow. Moss can in a small part, contribute to lifting a tile because it applies a little extra force along the edge but it doesn't force roots into gaps like other plants and pry layers apart. For the most part the tile has already started to fail/is already loose due to the decomposition of the nails/ wood underneath and would come down/split without the moss, albeit a bit more slowly. However, it does trap debris increasing moisture retention and while it won't damage harder materials, on wood tiles the higher moisture encourages fungi to grow which does. Failures are ultimately of delamination, (just like your plywood chair he said with a grin) due to moisture ingress and expansion along capillary lines which take longer to dry out whether the moss is there or not, the moss just increases the drying time a bit. He points out that a bit longer is because as moss dries it can then 'suck water' out of the crack although not as efficiently as holding it in.
Interesting the way it is laid make Welsh and Vermont slate some of the best in the world due to density and geological formation making them up to twice as durable as others. St. Asaph Cathedral, using Penrhyn slates, having only had birds to clean moss off, was removed after 400 years and reused.
Quick search didn't hit many 'scientific studies' but I read an investigation from a roofing company on other materials that I would've thunked were more susceptible to moss. They state moss isn't necessarily detrimental to roofs but the long term presence of water and penetration is (under investigating the problems)...
Roof failure investigation
if it hasn't already been mentioned.. NFRC advice..
NFRC re:moss
My personal takeaway from his advice: A LIGHT brush off with a very long handled brush if it concerns you (doesn't me) in the summer, anything else can cause more damage than leaving it there - make of it what you will..
edit: added advice and spell corrections
He tells me that slate is laid down in thin bedding layers makes it split 'beautifully along the planes of cleavage' (incidentally, not often along the bedding layers). It's these granular layers that allow moisture ingress especially along edges and where nails have caused micro fractures but also on the flat surface and result in exfoliation. He uses ' a tile' to denote any material shaped into a square or rectangle.
Where the edges are - if the bedding layers in on a slight angle you get the little flakes off the edges more readily than if they were laid perfectly flat but as it's granular the upward force will cause a rising crack. Moss spores will generally get rinsed off but these small breaks and gaps allow them to gather and grow. Moss can in a small part, contribute to lifting a tile because it applies a little extra force along the edge but it doesn't force roots into gaps like other plants and pry layers apart. For the most part the tile has already started to fail/is already loose due to the decomposition of the nails/ wood underneath and would come down/split without the moss, albeit a bit more slowly. However, it does trap debris increasing moisture retention and while it won't damage harder materials, on wood tiles the higher moisture encourages fungi to grow which does. Failures are ultimately of delamination, (just like your plywood chair he said with a grin) due to moisture ingress and expansion along capillary lines which take longer to dry out whether the moss is there or not, the moss just increases the drying time a bit. He points out that a bit longer is because as moss dries it can then 'suck water' out of the crack although not as efficiently as holding it in.
Interesting the way it is laid make Welsh and Vermont slate some of the best in the world due to density and geological formation making them up to twice as durable as others. St. Asaph Cathedral, using Penrhyn slates, having only had birds to clean moss off, was removed after 400 years and reused.
Quick search didn't hit many 'scientific studies' but I read an investigation from a roofing company on other materials that I would've thunked were more susceptible to moss. They state moss isn't necessarily detrimental to roofs but the long term presence of water and penetration is (under investigating the problems)...
Roof failure investigation
if it hasn't already been mentioned.. NFRC advice..
NFRC re:moss
My personal takeaway from his advice: A LIGHT brush off with a very long handled brush if it concerns you (doesn't me) in the summer, anything else can cause more damage than leaving it there - make of it what you will..
edit: added advice and spell corrections
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Jacob
What goes around comes around.
Make of it what you will? What else, except that I was right?
Probably.PS One common example of plant taking advantage of mortar cracks etc is the sight of a Buddleia shrub taken root on a chimney stack on a building in need of TLC.
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My friend ( Botanist ) and ex director of some of France's biggest national parks ( many of which include slate roofed buildings ) and who currently lives around 400 metres from me in a slate roofed house, agrees with me. He is still an official advisor on botanical matters to the French government and although retired is also a top advisor on such to the EU. Water contained in the structure of mosses is mildly acidic, this acidic* water attacks slates ( mosses "hold on" ) partially using this acidic etching , it allows the moss ( which doesn't have what we'd think of as normal "roots" to attach.Moss exploits micro crevices and enlarges them.Thus weakening whatever the moss is on, if the moss is holding water and the water freezes, this splitting effect is worsened, accelerating the substrate material failure. basically confirming, from a internationally accepted expert botanist's point of view what my chemistry background told me was happening.
* a complex mix of weak acids, including carbonic acid ( you know it as the acid in coca cola ) , you know what that does to mineral surfaces, such as calcium ( of teeth ) metals ( clean coins using coca cola ) and try slate in coca cola, you'll see the effect.
If moss grows on glass for along time ( many years ) it microscopically pits the glass, glass is not known for having surface fissures.Next time you see a deserted moss covered building with any windows, if you can, root around to find some glass with moss on .remove the moss by simple rubbing, wash to remove dirt. The glass surface is pitted.
* a complex mix of weak acids, including carbonic acid ( you know it as the acid in coca cola ) , you know what that does to mineral surfaces, such as calcium ( of teeth ) metals ( clean coins using coca cola ) and try slate in coca cola, you'll see the effect.
If moss grows on glass for along time ( many years ) it microscopically pits the glass, glass is not known for having surface fissures.Next time you see a deserted moss covered building with any windows, if you can, root around to find some glass with moss on .remove the moss by simple rubbing, wash to remove dirt. The glass surface is pitted.
Jacob
What goes around comes around.
Even worse if there is no moss and water gets straight in more easily, followed by frost.
I've rooted around and removed acres of old glass from buildings over the years, including crown glass 100s of years old from deserted moss covered buildings and have never ever seen moss or pitting on any of it.*
It was my main employment - all over Britain and one large 200 year old building in Ireland.
I've reused 150 year old glass in this building and it is in perfect condition, excepting occasionally a slight haze when the sun is on one or two pieces, which I am told is due to impurities and chemical change - sometimes leads to discolouration hardly noticeable.
I've got a bit of an obsession with old windows and joinery and have also looked at it all over the place.
I don't think I've anything else to say!
* PS sometimes moss on bottom rail ledges, glazing bars etc where the spores could settle and get started.
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@Titan_uk
I like Welsh slate, the manganese in the stuff around Barmouth and northwards from there gives it a beautiful slightly green sheen when dry and deep blue-green dark grey near to black when wet.The older slate here has similar colours, but the newer stuff is not so nice and doesn't match.Which is an emb*ggerance as I have to lay the new slates on my self built atelier roof and it is only 50cms from the house roof which has the older slates.
I like Welsh slate, the manganese in the stuff around Barmouth and northwards from there gives it a beautiful slightly green sheen when dry and deep blue-green dark grey near to black when wet.The older slate here has similar colours, but the newer stuff is not so nice and doesn't match.Which is an emb*ggerance as I have to lay the new slates on my self built atelier roof and it is only 50cms from the house roof which has the older slates.
I’m impressed. A thread about grass hitting 150 posts!
Jacob
What goes around comes around.
Moss hysteria?
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planesleuth
Established Member
Phosphoric Acid
Phosphoric Acid – The tartness of Coca-Cola comes from the use of phosphoric acid.
Phosphoric Acid – The tartness of Coca-Cola comes from the use of phosphoric acid.
planesleuth
Established Member
Chuck coca cola on your roof..that'll get rid of the moss!
I want to thank this thread, forum and you for your contrary view - What a fascinating plant! I'm going to make a moss garden!It was the moss which got them into a tizzy! Moss hysteria!
mwinfrance, with all due respect to your friend I'm not sure about the veracity of his claims as reading the international association of bryologists (great word) and from Oxford university.... 'form discs or ramify at their tips when they contact solid particles and adhere strongly' ... 'Attachment to the substrate may be facilitated by the production of adhesive sulfated non-cellulose polysaccharides by rhizoid tips' (Odu, 1989)
It doesn't damage which would loosen it's own hold by gluing itself on... brilliant!!
Ok I'm done and enthused
And CO2,( to make the bubbles ) hence they are referred to as "carbonated drinks" CO2 in water makes a dilute acid, although I agree, phosphoric is what gives the "tart"ness.No H3PO4 in moss run off ( or in waterheld in the spongyness of moss ) water.
Jacob
What goes around comes around.
Was Pete Marsh a bryologist?
Board did an Oooops!
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From that link
Note the parts about the acidity of water around moss..that does not just apply to sphagnum moss.
