Accoya, anyone used it.

Q

Quandary

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I was reading a construction technical mag. and my eye was caught by an ad. for 'Accoya' because they warrant durability of min. 50 years above ground and 25 years in the earth. They claim that timber modified by this process is suitable for marine use, including decking, with a moisture content about 20% of the original wood species used, and therefore minimal movement. There seem to be quite a number of places putting in the plant to convert to it, apparently they can't just use old vacuum pressure plant as the tanks and pipes have to be stainless steel, acetic acid? Current uses are joinery, windows, doors, cladding, decking, bridges etc. Unfortunately they do state that it is not suitable for continuous immersion in sea water so limited to joinery and decks etc. There are price indications suggesting that say 25x 100 plank is about a £5/m. so not that cheap but apparently it does not change the colour of the timber and can be painted or stained in the usual way. It seems to be worth considering for boat fitting out?
 
I hate to refer to another forum, but I posted a couple of topics related to this on the WoodenBoat forums, here and here. If you have any questions, do let me know. Chris
 
Thanks for the links, interesting reading but it looks like early days for marine applications. Here in West Scotland there is a lot of larch being felled ( though it is not the main species) and I have recently used it for cladding and shingles for an extension and also in building a hexagonal gazebo, structure, cladding, flooring, sarking etc. It was chosen for its attractive golden colour, (uncoated, it weathers to silver) its relative durability and because of its ready availabilty in local forests, sawn in the small mill run by the enthusiast members of the local green woodworkers club. Because the trees are slender, the boards and joists are limited to about 150mm. to avoid sapwood. It does cap and shake a bit when exposed to strong sunshine but the cladding on the north side is still pristine after four years. Imported Siberian larch from the big timber yards is several times more expensive. Larch was traditionally used for planking and decking fishing boats in Scotland. The Accoya process would seem to have the potential to make locally grown softwood timbers much more versatile. At present there is a ship leaving the pier here a couple of times a week with logs, the lumber goes off to Ireland for processing and the smaller stuff is used for pulp, some of this goes all the way to Finland. It seems a shame that now that we are in the middle of harvesting all the conifers planted all over Scotland in the sixties that we can not find an added value use for the wood at home other than just turning it into wood pellet fuel, perhaps not marine but at least construction and joinery? Accoya treated windows with a life exceeding 50 years would last much longer than the ubiqutious upvc and would be much nicer to live with.
 
Quandary,
Not sure if there was a question in there. We are put to task, regularly, regarding our sourcing of radiata pine from New Zealand and Chile for conversion to Accoya, but your points about larch would appear to be apropos for this discussion. When you consider the conifers in Scotland are much slower growing, radiata pine from NZ that is "upgraded" via acetylation presents an interested sustainability story. For reference, radiata pine forests in NZ produce about 28 to 38 m3/ha/yr, whereas a European larch forest produces about 5 to 10 m3/ha/yr. Most life cycle analyses don't take into account this mean annual increment differential. Also consider that Accoya is prolonging the useful life of what would otherwise be a very non-durable wood, while leaving the rain forest intact and reducing the need to fell as much timber, even your coniferous forest. Certainly not a compelling prospect to those in the timber industry, but considering population growth rates and the demands being placed on forestry, wood producers are not going to run out of customers any time soon. We certainly hope that the unique and profound performance enhancements with Accoya will result in renewal of wood as a building material into novel applications. (When was the last time you heard of a heavy-traffic bridge being built from wood?) A "Wood Renaissance", if you will.
 
grumpy_o_g said:
What does cap and shake mean please? I'm guessing that the wood doesn't actually start shivering??
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Cap means that the board 'bows or distorts from flat' when looked at from the end. Shake is another term for 'split' - but might be better described as 'a natural split through drying out or other natural process'. Since 'split' might be something that you 'do' to the wood. I hope that makes sense?

A professional wood worker will be along shortly to put me right I expect.
 
Kebony yacht decking

Norman_E said:
I think he is using Kebony, which is a different process involving both impregnation and heating.
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It is correct that the decking and some of the interior woodwork was done in Kebony on the Contessa 32.
Elan yachts are using Kebony as standard on all their 444 Impressions and will add another model in 2011. Several other Norwegian boat builders are using Kebony as standard, and some have it as an alternative to teak.
Kebony is currently being evaluated by some of the largest boatbuilders in Europe.
 
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