Treated Timber

Dunno what became of my first post on this subject; let's try again...

Is the treated timber you get from timber merchants treated more than just superficially? Will sanding the somewhat rough sawn surfaces damage the rot-proofing in any way? I'm planning on painting it you see...

Reply to
Chris
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Its usually pressure treated - so the treatment penetrates a few mm into the wood. So as long as you don't sand too heavily it will retain some treatment. (although don't breathe the dust!)

Reply to
John Rumm

Thicker stuff is pressure treated eg posts. ie put in a vacuum chamber, sprayed and when the air is admitted the preservative is driven right in.

Thinner stuff is just dipped and allowed to drain off., eg fencing panels.

The problem arises because they no longer use the traditional arsenic/copper (banned) So stuff has gone from being virtually indestructible to lasting five or six years.

As the treatment is usually green, you can see how far in it's gone on the cut ends. Usually not far. Cut ends should be treated by hand brush & wood preserver.

Reply to
harry

There is some confusion here. Historically, the only truly effective treat ment was CCA (water borne copper/chrome/arsenic under pressure) where heavy metal ions combined with hydroxyl groups in the timber and thus was chemic ally fixed. The German EEC eco greens @@@@ed that up for us. The modern eq uivalent is not as effective and any cut or sanded ends MUST be site treate d after cutting. The treatment requires air to be REMOVED first not pushed in . It is a do uble vacuum process. Double vac USED to be with organic solvents but that too has been banned an y it is now water based aqua vac. (For joinery) neither process should be s anded or cut. For fence posts the only effective treatment now available i s creosote in accordance with the right CEN or BS number

Reply to
cjdgeorge

Well that depends. I think looking at some of the bits cut off on my new fence that it penetrates to a point. A point very variable but not all the way through acne I hope the fence builders did slosh something on the ends before they put them up! My guess is that its dipped in something or other. Brian

Reply to
Brian Gaff

Yes indeedy. The EU have f***ed up far more than that for us over the decades. All the great stuff you could rely on in days gone by is now largely banned. :( Still, we're leaving so... Rejoice! :)

Reply to
Cursitor Doom

Sucked right in? ;-)

Cheers, T i m

Reply to
T i m

When I was buying timber ~12 years ago, the only treated timber available which still had any effective treatment applied was roofing battens. Effective treatment was no longer permitted to be used on anything else. Rules may have changed since then, but almost certainly less favorably.

Reply to
Andrew Gabriel

"Leaving" in name only it would seem so ultimately nothing will change.

Reply to
www.GymRatZ.co.uk

They are banned by all major countries and trading blocks in the world. There is zero chance of us allowing their reintroduction. Nothing to do with the EU, but science discovering they rapidly leach out into the environment and end up in food as well as other damage.

Reply to
Andrew Gabriel

Pushed right in - enjoy!

Vacuum inside, atmospheric pressure outside, liquid pushed in by pressure.

Reply to
PeterC

Yeahbut the 'preservative is only pushed in *because* of the vacuum?

If you have a pressure vessel at atmospheric, add preservative then pressurise it, you drive preservative in. When you return the vessel to atmospheric then some preservative will be sucked back out.

If you have a pressure vessel, reduce the pressure inside the vessel, introduce the preservative and then allow the vessel to return to atmospheric, the preservative would be sucked in.

It's described as 'sucked' (by me anyway ) because of the relative pressures and the direction of the preservative?

Cheers, T i m

Reply to
T i m

You do not get any leaching once the timber is fixed after 72 hours of curi ng. There is a CHEMICAL bond with the hydroxyl groups in the wood. That was the beauty of CCA. It was political joe towing to the Greens -not evidenc e or science. Disposal was cited as a ?reason?. The present processing is more oron to leaching. Sadly, even if we leave, it is unlikely that any Gov will have the balls to allow a CCA plant a lice nce...

Reply to
cjdgeorge

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