On Jun 24, 10:02 am, wrote:
On 24 Jun, 05:54, "

wrote:
What colour should tanalised timber fence panels be straight from the
supplier? They're the feather edged variety, not lap.

A neighbout had some installed and they're a faded orange. I was
pretty sure that tanalised (Tanalith E) stuff is green, which seems to
be confirmed by the manufacturers:http://www.archchemicals.com/Fed/WOO..._DS_OCT_02.pdf

So I was a bit surprised when my tanaliased panels arrived and they're
that faded orange colour too. Should they be green?

Dear Bromley86

Tanalised timber used to be quite specifically “CCA” (Copper Chrome
Arsenate) in a water borne process, originally developed at the Forest
Research Institute in Dehra Dun, India. Its great property is that it
chemically combines with the hydroxyl groups on the timber and cannot,
therefore, be leached out by ponding or wicking when subjected to
passing water and fights the tendency of mycelial sacrificial hyphae
to translocate away from the hyphal front the heavy metal ions that do
the protection.
It had to remain in the treatment plant for (I think) 48 hours for the
chromium (7?) salts to fix and change because until it was fixed the
product was carcinogenic. Once fixed, the surface was fine and even ok
for children’s play grounds...then the Americans and the EU got their
teeth in (mainly a sop to the German “greens” in banning arsenic)and
had their way...
By studying decaying treated timber in compost (which is not the same
as ground contact) they discovered alleged leaching – which may well
have been translocation – and that was that! Other countries climbed
on the bandwagon as a purely precautionary measure even though the
product had been used for years with no epidemiological data to
suggest a problem.

The EU in its wisdom has taken away our facility to use arsenic and
the product is not longer the same.

Tanalith E is different in that it is “ a waterborne product based on
copper triazole technology. Copper is derived from recycled sources
and triazoles are organic biodegradable biocides, commonly used to
protect many of the food crops we eat.”
Seehttp://www.archchemicals.com/Fed/WOOD/Docs/Tanal_E_process.pdf

No chrome – no arsenic

The alternative water borne chemicals used are now
Alkaline copper quaternary (ACQ)
Copper azole (see above)
Various other copper compounds

Water borne pressure treated timber with other than CCA or Tantath E
should not
really be called “tanalised” which is a registered trade name and
product

Seehttp://www.archchemicals.com/Fed/WOOD/Products/PreservativeProtection....

“Pressure Treated Timber With Built-In Colour
TANATONE pressure treated timber has been impregnated with TANALITH E
preservative containing a built-in brown colour. TANATONE is usually
specified for fencing and landscaping applications, eliminating the
need for brush applied colour at the point of installation.”

Mention was made in a later post of a dipped product.
This is not to be confused with or even compared with a pressure
impregnated product. The two perform quite differently.

Mention was also made of the Protim process (aka double vac or vac-
vac). This also is quite different. It used to be an OS borne
preservative (and technically still is) that got an active ingredient
into the timber without dimensional changes or, most importantly any
chemical fixing so it is less effective, and is used for internal
joinery and things like roof battens.
All such active ingredients are relatively easily leached out.

Nowadays the EU directive on such OSs have resulted in the development
of Aquavac where water is the carrier fluid. Result? Dimensional
changes to joinery – ok not bad ones but not good for high quality end
products

A coloured oil will be of limited use as its main function will be
water repellancy and UV protection with limited action as a fungicide.
It may look nice but that’s not much use if it rots!

Colour could be result of an added colouring agent or the active
ingredient
Simply ring up your supplier and ask what precisely he has supplied
and if it is not tanalith send it back!

Chris George

Right. Can someone add this to the timber FAQ (or correct it).