pressure treated timber - worth painting with preservative?

[ldsau93]

Just out of curousity, does any body else add further coats of preservative to wood that is already treated (normally tannelised)?

Previously I didn't, but having once cut a piece of 'treated' wood I was surprised that the treatment by no means pentrated the full depth - so have since always given at least 2 coats of creocote or similar.

Thoughts on a (electronic) postcard please!

[ESBkevin]

Pressure treated just means its been dipped in a bath of the preservative for a short time rather than brushed on or sprayed. In theory it covers everything better but the depth penetration depends on the length of time (few seconds to a few minutes) and how dry/absorbent the timber was when dipped.

[roitelet]

You could give it a good soaking of linseed oil to help the preservation.

[Bill Door]

As ESBKevin said. But sometimes standing near the road watching the cars and people go by will make the day go quicker! It also gets you out of the way of washing the dishes, ironing the cloths and ordering more unwanted seeds from the catalogues!

Bill

[Potstubsdustbins]

Sorry to gain say you people but you haven't quite got it right.

Pressure treatment consists of a little bit more than just dipping in a bath of preservative, well a lot more actually.

First the timber is air dried, it is then loaded into a pressure chamber (looks a lot like a decompression chamber used by divers). The air in the chamber is then evacuated to create a vacuum to draw out the remaining moisture, after this it is flooded with the preservative and then pressurised to force the treatment into the timber. After the allotted time the chamber is vented back to atmospheric pressure and the timber is withdrawn and stacked in a drying area.

Not many know but pressure treated timber is not all the same it is classed from U 1 to 4 dependent on what it is to be used for, this will affect the treatment used and the time under vacuum & pressure. U4 is the most durable and is for direct contact with soil or fresh water, where as U1 is for internal use.

[ldsau93]

Thanks for those thoughts.

The project in hand is 50mm timber stakes that will be used for a double-post system for raspberries.

I'm hoping the arrangement will outlast me (I'm 46...) so have given the posts 3 coats of creocote. The posts won't go directly in the ground - first i'm going to sink a 45cm length of 68mm down-pipe into which the post will be slotted, then topped up with postcrete.

This will give a regular 'sleeve', minimize exposure to water and minimise the amount of postcrete (£5 a pop...).

[Potstubsdustbins]

Well I hope the system does NOT out last you, at 46 I would much prefer to be renewing it in 30 years time.

Having said that I know where you are coming from. 25 years ago I updated my heating system, new boiler, full bag of mashing's with the same philosophy. Now I am very glad I survived to replace it.

[Kirk]

I have painted pressure treated timber with a coating more then more preservative - actually both as well. The coating was a cheap Wilkinsons timber one that I bought that looked awful when in the tin. It is more for protection from water I think then a preservative specifically. I painted it on some treated timber to add additional protection and use it up. Actually dries to a better colour/finish then expected.

Last thing I covered, 2 lengths of decking, was actually with a bottle of Red Ceder stuff from Poundland and then the Wilkinsons timber stuff. Made them red and the coating lessened the impact.

Seems to be a useful combination, at least the protective coating stuff, slows down the water/moisture ingress. Will say that having it around doing nothing meant it was an ideal thing to try as it couldn't do any harm and I already had bought it. However having used it I am likely to pick up another tin when I use the present one as I think it is of some benefit.

If you want to change the colour then the wood preservative, if it actually preserves I am doubtful, from Poundland in one of their 3 options will do that, then this Wilkinsons stuff on top sort of makes it all a half reasonable finish. The Red is a bit bright.