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Is Aluminium wood primer any good at preventing exterior wood rotting?

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Simon Robinson 411/05/2018 17:48:47
74 forum posts

I’ve heard they use aluminium wood primer on boats. But is it any good on exterior soft wood at preventing the wood rotting.

I have a new untreated shed and I’m coating the sides in Cuprinol shades paint. Is it better if I do the areas at high risk such as the bottom of the frame etc in Aluminium wood primer or is my Cuprinol good enough?

Grindstone Cowboy11/05/2018 17:54:16
854 forum posts
64 photos

No real evidence, but my dad always said aluminium paint was the best primer for wood or metal.

Speedy Builder511/05/2018 18:36:49
2590 forum posts
207 photos

I don't know, I can say it drops off my beehives after about 3 years. I am chancing my bets on this stuff
Lifetime Wood treatment enquiries@thenaturalgardener.co.uk
BobH

Trevor Crossman 111/05/2018 18:38:19
152 forum posts
18 photos

Hi Simon​ , I'm not sure if aluminium primer would much improve an already very good product. I live in a wooden clad house which has been painted with Cuprinol shades and not one board has rotted over the past 15 years or so,the I repaint the 'weather' side annually and the remainder bi-annually. My workshop is similarly constructed and painted and that too is okay, only one board has had rot where a hidden ants nest piled a load of soil up inside the wall void due to my less than perfect damp course under the bottom timber. Make sure that the tin is very well stirred before use because it does settle out in storage. Trevor.

John Haine11/05/2018 19:51:03
4622 forum posts
273 photos

If it does rot there's a great Cuprinol product that is a resin dissolved in solvent that soaks into rotten wood and sets hard as - well, wood!

Simon Robinson 411/05/2018 23:58:51
74 forum posts

Posted by Trevor Crossman 1 on 11/05/2018 18:38:19:

Hi Simon​ , I'm not sure if aluminium primer would much improve an already very good product. I live in a wooden clad house which has been painted with Cuprinol shades and not one board has rotted over the past 15 years or so,the I repaint the 'weather' side annually and the remainder bi-annually. My workshop is similarly constructed and painted and that too is okay, only one board has had rot where a hidden ants nest piled a load of soil up inside the wall void due to my less than perfect damp course under the bottom timber. Make sure that the tin is very well stirred before use because it does settle out in storage. Trevor.

Hi Thanks for your advice Trevor. What would you recommend for the underside of the shed floor? It’s tongue and grove on an underside frame of 1” x 1” that will be mounted on 3” x 3” pressure treated posts laid flat on a solid concrete base.

I thought of creosote by the smell is rather off putting for my family, I have some cheap Wilkinson’s red cedar wood preserver....Any other ideas of what I could use?

J Hancock12/05/2018 08:18:45
832 forum posts

You need to contact a supplier of wooden framed Cooling towers and ask what product they use.

Now that is really good stuff .

John Haine12/05/2018 08:38:28
4622 forum posts
273 photos

Also look at Sadolin.

Circlip12/05/2018 08:53:31
1499 forum posts

For floor underside, either genuine Creosote or a heavy Bitumastic paint.

Regards Ian.

Trevor Crossman 112/05/2018 09:08:36
152 forum posts
18 photos
Posted by Simon Robinson 4 on 11/05/2018 23:58:5

Hi Thanks for your advice Trevor. What would you recommend for the underside of the shed floor? It’s tongue and grove on an underside frame of 1” x 1” that will be mounted on 3” x 3” pressure treated posts laid flat on a solid concrete base.

I thought of creosote by the smell is rather off putting for my family, I have some cheap Wilkinson’s red cedar wood preserver....Any other ideas of what I could use?

I would think that the old of cheap = no good should apply here! In my experience the only​ thing that works long term to prevent wood rot is genuine creosote, none of the modern ''green planet saving eco friendly'' substitutes work over the long term, so do not be confused by the product 'Creocote', it's not the same stuff . You will have to find a friendly fencing contractor to get proper creosote as it is no longer available for retail sale to the general public. Perhaps the next best thing to prevent rot on the underside of your shed floor would be Black Bitumen paint, this does not have such a long term smell as creosote, I think you'd get this okay from a builder's merchant. Farm buildings that I constructed 30 years ago with properly creosote treated timber are still in good condition ,unlike some of my current neighbour's rotting 7 year old fence posts treated with a modern product. On the other hand, why not use a concrete floor?

Trevor.

Mike12/05/2018 09:32:26
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713 forum posts
6 photos

I'd agree about creosote preserving wood, but a possible warning: I once used it on exterior-quality plywood, and it caused it to de-laminate. Of course, it could have been a dodgy sheet of plywood. Any thoughts, gentlemen?

SillyOldDuffer12/05/2018 10:13:30
Moderator
8468 forum posts
1885 photos

Apologies if it's already been mentioned, but mixing different types of preservative and/or techniques is unlikely to work well. For example, aluminium primer isn't compatible with creosote, and I doubt it goes with Cuprinol either. (Read the instructions!)

My understanding is that aluminium primer bonds better to clean wood of most types than the alternatives. (But not all.) Not a magic preservative in itself, aluminium primer forms a solid base for the layers of conventional paint that keep out water, fungi, bacteria and insects. It's the conventional paint that does the work and you want it to stick. After that the paintwork has to be carefully maintained; if neglected, the barrier is breached allowing nasty things to happen under the surface whatever you do.

Slapping chemicals about is unlikely to preserve wood well. Doing it properly is a multi-stage process:

  1. Seasoning the wood under cover over several years. This dries the wood throughout without causing cracks and minimises biological contamination .
  2. Leaving the wood for several days in a vacuum before flooding it with a powerful disinfectant / insect repellent. The vacuum removes water and ensures the disinfectant penetrates deep into the wood.
  3. Finally, leaving the wood to soak for several more years before using it. In the 19th century it was recommended that telegraph poles be immersed for 30 years before use.

These processes are expensive to the point that it's cheaper to replace than preserve. Thus:

  • Wood is likely to be kiln-dried rather than properly seasoned, leaving it slightly damp, porous and perhaps biologically active.
  • Probably only given a short soak or surface treatment before immediate sale. The chemicals used are powerful, but applied superficially.

Creosote is nasty stuff; use it with care. It's as likely to hurt the user and bystanders as the environment, and it makes wood extra inflammable. The Victorians took to creosote mostly because it was a cheap by-product from gas-works and coking ovens. They didn't rate it as highly as Bichloride of Mercury. Try buying that on the internet...

With a new shed, keep it as dry as possible, and maintain it regularly with the original product. You can't fit and forget - it's made of a natural product highly liable to rot. Much depends on local conditions: mine is built on a low concrete wall in a sheltered position. The wood lasted far better than my house window frames only 20m away; the difference is that the house catches lots of sun and rain.

Dave

Neil Wyatt12/05/2018 10:49:52
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Moderator
18990 forum posts
734 photos
80 articles

Keep up at the back, Dave.

Pressure treated tanelised softwood should be good for a minimum of 16 years in contact with normal soil (e.g. fenceposts) and usually 25+ in practice.

Where so many people go wrong is in buying 2400mm lengths and chopping them to length without treating the cut ends...

The best solution for all wood is keeping it away from the soil, if it can regularly dry out it will rot only slowly.

My experience is the good quality brush on treatments are pretty much as good as brushed on creosote.

Samsaranda12/05/2018 10:53:18
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1396 forum posts
5 photos

Unfortunately the trend with modern wood treatments is “that they allow the wood to breathe” which is the root of rotting problems, the finish is micro porous allowing moisture to penetrate and hence spores to create rot. Because of H&S legislation members of the public are protected from any chemicals which would be effective in preserving the wood structure, hence not being able to obtain creosote etc. At my last house some 40 years ago I erected a wooden fence and treated it liberally with a mixture of proper creosote and old engine oil, yes it smelt awful for a while, but it is still standing. My advice would be that aluminium primer will only act as a very temporary surface shield to the wood, you need to treat the wood with a product that will penetrate into the wood and kill or inhibit rot getting a hold. My vote is if you can get hold of “ proper “ creosote then that will probably last years longer than modern products that are available, yes it will smell for a while but is that a penalty if the wood is going to last. Modern “treated” timber is a joke, since they removed the arsenic compounds from the treatment compounds it rots away in just a couple of years. We have a pergola that I put up in our garden 25 years ago using treated timber that was from before when they removed the arsenic and the pergola is still sound with no rot apparent. Good luck with your project, the secret is going to be to keep the water away from the wood as much as possible so perhaps concrete floor and wooden side walls built on dwarf concrete walls perhaps 9 inches high.

Dave W

Gordon W12/05/2018 11:24:22
2011 forum posts

Pressure treated tantalised timber has been used for years now. We used it for farm buildings and it will last many years, in some cases outlasts concrete posts and even steel, esp. when in contact with animal waste.

Former Member12/05/2018 11:26:55
1329 forum posts

[This posting has been removed]

Samsaranda12/05/2018 11:44:30
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1396 forum posts
5 photos

Gordon I think that you will find present day tantalised timber is somewhat different from that a few years ago, they have removed the arsenic compounds from the preservative used now and the timber is now very susceptible to rot, depends on the timber used of course, oak is very good but extremely expensive nowadays.

Dave W

Gordon W12/05/2018 12:07:21
2011 forum posts

Dave W, you may well be correct, it was 30 -40 yrs ago when I was in that job. For interest, a new pole was put in about 6 yrs ago by BT, it looked as if creosoted . Now the bottom of pole is thick in black tarry stuff and the top is nice clean wood. What's that likely to be ?

Mike12/05/2018 12:52:32
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713 forum posts
6 photos

When my dad was in the electricity supply business in the 1960s and 1970s, they considerably extended the life of poles which had been in service for a few years by injecting them. A spiked collar was put around the pole, and an injection of what my dad described as "an evil-smelling yellow substance" was injected through the spikes. Speaking of tanalised timber, my original workshop at my home in Lincolnshire was made of tanalised pine. The company that built it said they couldn't work with the timber until at least two weeks after treatment because of the danger of arsenic poisoning. The building was guaranteed for 40 years, and if I look at my old address on Google Earth I see that it has been demolished some time in the last two years. It was built around 45 years ago, but the last time I saw it when I visited my old home town, the house's owners had allowed it to get covered in moss and fungus, and had failed to renew the felted roof.. I think that if it had been looked after properly it would still be standing.

Samsaranda12/05/2018 13:49:52
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1396 forum posts
5 photos

Gordon I would think that the thick black tarry stuff is a tar compound of some kind which just encapsulates the bottom of the poles where they are in contact with the ground and therefore prevents water from reaching the wood, but I am just guessing here.

Dave W

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