Posted by Per Corell on March 13, 2003 at 03:56:47:
In Reply to: ArchWeek - Arsenic in Wood - Dangers Persist posted by Kevin Matthews on March 12, 2003 at 13:58:02:
When you discuss this issue from the experience of the craftmen with hands-on experience, you se that when protecting wood against rot, you do not do this by chemical agents but by knowing what caurse the rot and attack the rot by making sure there is no water around to make the rot grow.
So most of the agents can be replaced with a bit more knowleage about where and how you place the wood members and how you keep away what feet the rot. Now please exchouse that I refere my own crafts and even do it in historic terms, still I take the chance and I am sure that you will extract the simullarity of how this way of thinking survived untill today.
Anyway in the old day's captains with small costal cargo vessels allway's tried to get a salt cargo with their new wooden ship ; as salt was known as an agent to keep food and salt fish, people in those times thought that "salting" was a relevant mean to protect wood in vessels ------- quite a natural thought, but science soon made an end to this way of treading wood in shipyards even this fait live on nomatter what science say.
Agents only penetrate a milimeter of the wood and any woodworker have seen that preasure treaded wood rot as well as any other wood, on the other hand a piece of wood that is placed with care in a building structure will work for centuries, as long as the structure are made so, that the watr are kept away so the rot can not grow.
The old sea captains did not se the result of pooring salt around the ships frames but the nails and steel bolts that kept the ship together only lasted halve the time so you can ask where the profit was ,esp. as nomatter how salt the sea is, the wooden boat will rot as rot don't even care if you spil parafin or diesel or antifreze onto the wood as this only penetrate a millimeter or two.
The true weapon against rot is not poison but the skills of the craftmen putting up your house ; placing the fume membrame wrong and the wood will rot nomatter how well treaded with poison , so why not accept these facts, that wood is not plastic and placing a piece of wood dry make it work forever, while making a bad design make the house rot.
Anyway if this is about selling low quality wood as high quality wood, then it is better making it into sheet materials so it realy is possible to protect the organic material with non-poison agents working by keeping the water out instead of inviting the rot with the water that is allowed to enter the wood.
My experience is, that even a thin film of linseed oil will protect much better by creating an osmosis membram allowing fumes to escape and make it more difficult for water to enter, and even in open air the time when it rain and is damp, is shorter than the time where a wood surface are left to fume away the water if an open osmosis membrame are added.
Dry condisions are the vorse condisions for rot and dry condisions is the vorse "poison" for rot. Beside much of the idear behind poisining wood, go back to the times where fish was salted and craftmen know that preasure treading just try to make veak wood into reliable wood.
Now if you check textbooks about wood, you will se that each specie are good for this or that, this mean that wood is not just wood, and if you got the chance you choce Oak for what Oak is good for and Pine for what Pine are good for, ----- wood hold natural agents that protect wood for a number of years and "Rot" is not just rot but a number of species where one live from the one before ; in pine the first rot is the harmless black spots, but the harmfull rot eat this rot not the wood ( this is a very simplified picture ).
Anyway just the "salting" discussion that raged when ships was of wood and captains of steel ,show what you are up against fighting ignorance about what wood is and how rot work ; even today there are people who think that salt will protect a wooden boat and all sorts of poison are used to fight rot, where a more educated aproach would make timbers last double without any poison ,just with a thin linseed oil treatment.
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