Tanalised Timber warning from uk.diy
Duncan Russell
timber could be such a problem. I was thinking of rebuilding my raised beds
using this but may have to have a rethink now.
Duncan
Andrew Henry wrote:
This is from memory so apologies for any inaccuracies:
The preservation of timber (tanalising) is carried out using a mixture of
salts
of copper sulphate, potassium dichromate and arsenic pentoxide. The timber
is
pressure injected with the preservation liquid in large pressure cylinders,
after which it is stacked in the yard while still wet with preservation
chemicals.
Tanalising uses a substance called CCA which is Copper , Chromium and
Arsenic.
This is fine in dry conditions, but in the wet the chemicals can leach out,
and
the arsenic can be transferred to the hands simply from touching the timber.
Children in particular are prone to use their hands for eating without
washing
them first, and can get arsenic poisoning as a result. Food plants grown
near
to tanalised decking can accumulate sufficient chromium to cause the
symptoms
of heavy metal poisoning in anyone eating the produce.
An example is cited of a family in the antipodes who used offcuts of
tanalised
timber on their barbecue, the cooked meat killed their dog and resulted in
prolonged hospitalisation of the entire family.
Recommendations include avoiding drilling or sawing, using a dustmask if
these
are unavoidable, washing thoroughly after touching tanalised timber, and
avoiding use where people are likely to come into contact with the treated
timber.
--
The views expressed are my own and may not represent those of my employer
Colin McLatchie
heavy metal vapours. And I've always preferred hickory smoke to chromium.
But let's get real on the idea that the chemicals leach easily. They dont. One
perspective on this is that in California they have to stick a health warning
on fine bone china (like Wedgewood or Royal Doulton) saying that the glaze
contains lead and that it may leach if you leave it submerged in a vat of
orange juice for half your life (or words to that effect). To the best of my
knowledge tanalised timber gets off lightly with the friendly advice that you
not burn it. And I agree that I wouldn't throw sawdust into the compost heap
for my vegetables either!
See the following from http://www.trp.dundee.ac.uk/research/glossary/wood.html
which is the site of the Town and Regional Planing Dept of the University of Dundee....
"Timber can be pretreated against rot and insect attack. The most common
treatment is CCA, copper chrome/arsnic which sounds alarming, but is generally
held to be safe, because the chemicals used do not leech out, various brand
names exist for this process, cellcured, tanalised etc."
Are there any knowledgeable chemists out there who can comment?
cheers, Colin
MuckEpup
In article <70n5pp$2b...@newton.cc.rl.ac.uk>, "Duncan Russell"
<D.Ru...@rl.ac.uk> writes:
>I just found this on uk.diy newsgroup, fascinating I never knew tanalised
>timber could be such a problem.
[small snip]
>The preservation of timber (tanalising) is carried out using a mixture of
>salts
>of copper sulphate, potassium dichromate and arsenic pentoxide. The timber
>is
>*pressure* injected with the preservation liquid in large pressure cylinders,
So does that mean 'pressure treated' timber is tanalised timber??
---------------------------------------------
Chase the cats away for e-mail
8=8
Chris French and Helen Johnson
<muck...@aol.com.cats> writes
>
>In article <70n5pp$2b...@newton.cc.rl.ac.uk>, "Duncan Russell"
><D.Ru...@rl.ac.uk> writes:
>
>>I just found this on uk.diy newsgroup, fascinating I never knew tanalised
>>timber could be such a problem.
> [small snip]
>>The preservation of timber (tanalising) is carried out using a mixture of
>>salts
>>of copper sulphate, potassium dichromate and arsenic pentoxide. The timber
>>is
>>*pressure* injected with the preservation liquid in large pressure cylinders,
>
>So does that mean 'pressure treated' timber is tanalised timber??
>
>
pressure treating process, using specific chemical compounds, but has
become a generic term, a la Hoover. Wether or not all pressure-treated
timber uses the same chemical compounds (quite likely) I'm not sure.
I haven't yet seen the article in the HDRA news which prompted this
posting to uk.d-i-y. But going from the debates there have been on some
of the more US focussed ng's and mail-lists, hard evidence on wether or
not the compounds leach out into the soil in appreciable amounts, enough
to affect the soil, and to accumulate in plants is hard to come by. Or
rather, it is somewhat contradictory.
Just because you shouldn't burn the stuff, and take care when handling
the stuff, does not mean it will cause a problem in the plants grown
near it.
I'm not sure what the current attitude of conservation groups like the
BTCV is, A few years ago, when I was doing a lot of work for them, we
used to use it all the time for step building, bridges etc.
I agree it is a cause for concern, but I'd dearly like to have some good
evidence on this topic.
--
Chris French and Helen Johnson
Leeds
Email address valid for at least two weeks from posting
Alan Gould
>>I just found this on uk.diy newsgroup, fascinating I never knew tanalised
>>timber could be such a problem.
> [small snip]
>>The preservation of timber (tanalising) is carried out using a mixture of
>>salts
>>of copper sulphate, potassium dichromate and arsenic pentoxide. The timber
>>is
>>*pressure* injected with the preservation liquid in large pressure cylinders,
>
>So does that mean 'pressure treated' timber is tanalised timber??
Tanalising is a pressure treatment of timber, but it is not the only
one, so 'pressure treated' may or may not mean tanalised.
--
Alan Gould
david croft
The council estate where my mother lives had all there fencing replaced
about ten years ago,and according to the contracters the wood used had been
tanalised.As i type this the fencing is being replaced again,makes you
wonder.Incidentaly the fencing being removed is as good as new where it has
not been vandalized,and the vandalism doesn`t warrant all the fencing to be
replaced.
cormaic
French and Helen Johnson <news...@spennithorne.demon.co.uk>
declared:
8<---S-N-I-P--->8
>I agree it is a cause for concern, but I'd dearly like to have some good
>evidence on this topic.
I've received some brochures and technical literature from a
timber decking company that sources all it's lumber in the USA. There
is some brief mention of the 'benefits' of CCA treatment for outdoor
timber, and why they rave about it in North America. I'll have a root
about in the pile of paperwork on my desk and see if I can locate it
and post it to the group.
--
cormaic - paving pages at http://www.tmac.clara.net/paving2.htm
Culcheth - Last Updated on September 27th 1998
cormaic CAN BE FOUND AT tmac DOT clara DOT net
anti...@addr.in.my.sig
>So does that mean 'pressure treated' timber is tanalised timber??
Not necessarily. But if it has that pale green hue, it is probably
Tanalised.
Pressure treated *used* to mean: put in a chamber, extract air, lower
into creosote or a gunge of tar products. Many telegraph poles and
old fence posts have been treated this way.
--
Please reply to: rec...@cults.dircon.co.uk
paulw...@my-dejanews.com
"Duncan Russell" <D.Ru...@rl.ac.uk> wrote:
> I just found this on uk.diy newsgroup, fascinating I never knew tanalised
> using this but may have to have a rethink now.
>
> Duncan
>
> Andrew Henry wrote:
> This is from memory so apologies for any inaccuracies:
Do we have any authorititive information than someone's memory of
an uncited source? Or is this another FOAF story?
BugBear.
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
ahe...@cyberpass.net
paulw...@my-dejanews.com wrote:
> In article <70n5pp$2b...@newton.cc.rl.ac.uk>,
> "Duncan Russell" <D.Ru...@rl.ac.uk> wrote:
> > I just found this on uk.diy newsgroup, fascinating I never knew tanalised
> > timber could be such a problem.
> Do we have any authorititive information than someone's memory of
> an uncited source? Or is this another FOAF story?
The original source for the story was in the Henry Doubleday Research
Association newsletter. Jon Rouse posted a message to uk.d-i-y where
he said that he had read the story about tanalised wood and that he would
"avoid it like the plague". I emailed Jon to ask if he could expand
a bit more as I couldn't see anything about it at the HDRA WWW site.
Jon's summarised the HDRA article from his memory. This was what was
posted to uk.rec.gardening.
If you want more detail, then contact the HDRA at http://www.hdra.org.uk/
or enqu...@hdra.org.uk
--
Andrew Henry
ahe...@cyberpass.net
Jon Rouse
>
> Pressure treated *used* to mean: put in a chamber, extract air, lower
> into creosote or a gunge of tar products. Many telegraph poles and
> old fence posts have been treated this way.
According to the most informative catalogue I just received from Forest
(not the smoking group!) this is exactly how they do it now, except that
they use CCA in place of cresote.
cormaic
cor...@NOSPAMTODAYTHANKStmac.clara.net (cormaic) declared:
>
> I've received some brochures and technical literature from a
>timber decking company that sources all it's lumber in the USA. There
>is some brief mention of the 'benefits' of CCA treatment for outdoor
>timber, and why they rave about it in North America. I'll have a root
>about in the pile of paperwork on my desk and see if I can locate it
>and post it to the group.
I know it's following up my own post, but I've found the
brochure I was looking for. It is published by Cox Wood Preserving
(Inc., I suppose) of PO Box 1124 Orangeburg, SC 29116, USA and they
have a web-site at... www.coxwood.com.
They make a big song and dance about Chromated Copper Arsenate
(CCA) pressure treated timber being correctly dried after treatment...
"The benefits are numerous for CCA pressure treated wood that
is re-dried after treatment:
Dry Pressure Treated Lumber (DPTL) minimizes (sic) shrinkage problems.
DPTL has greater strength and stiffness.
DPTL is more uniform in size.
DPTL has better nail and bolt holding power
DPTL is safer.
DPTL is cleaner and lighter.
DPTL can easily be painted, stained, water-repellant coated, or left
to weather to a natural driftwood gray. (sic)
DPTL meets building codes, FHA (Fed. Housing Admin.), and grade stamp
requirements."
Later, it continues...
"Today with the heightened concerns about the potential
hazards of chemicals, there are two things that should be considered
when specifying or purchasing CCA pressure-treated wood: 1) that it is
safe, and 2) that it works.
The re-drying of CCA pressure-treated lumber is the *only* way
to insure (sic) immediate and complete fixation of the chemicals
within the wood cells, providing a safe, clean, and durable building
material."
Ok! So it's not definitive 'proof', but it should give those
of you concerned about CCA, somewhere to start your researches. :~)
Accordingly, it ain't cheap - I have been quoted a trade price
of 7 quid+VAT for each 38x88x3050mm length!!!
If anyone wants further info, feel free to email me.
Jon Rouse
>
> Do we have any authorititive information than someone's memory of
> an uncited source? Or is this another FOAF story?
Sometimes its worth going back to the source rather than looking at
quotes of quotes.
As the original poster in uk.d-i-y I did say that I was quoting the HDRA
article from memory.
If you want to see the original, try and get hold of the HDRA magazine.