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Old 31st Aug 2017, 10:29 am   #40
ms660
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Join Date: Apr 2011
Location: Cornwall, UK.
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Default Re: Woodworm damaged cabinets

Quote:
Originally Posted by emeritus View Post
I was recently looking for info on Tanalising solution that you can get for treating the faces of Tanalised timber that have been exposed by sawing or notching, and found a farmers' forum complaining about the short life of fence posts that now exists since the original Tanalising solution was changed to omit a poisonous ingredient that made it work. Apparently the manufacturers had assured everyone that the new formula was just as effective, but the fence post suppliers found it wasn't, and successfully sued the makers. Unfortunately that doesn't help anyone that wants durable wooden posts as the original stuff remains unavailable, so posts that used to last at least 25 years now barely last five.
In the trade we called it "end treatment" to treat cut surfaces.

You have to be careful when comparing the effectiveness of new treatment fluids against old treatment fluids, particularly with ground contact timbers such as fence post etc because in a lot of cases the physical aspects of the timber has changed somewhat prior to treatment with the actual fluid, eg: different species, methods of debarking/preparation etc etc.

You have to remember that with fluid treatment the heartwood of the timber is not penetrated enough (without assistance) for sufficient chemical retention, that's just the law of nature, in other words the way trees grow.

The part of the timber that will take the fluid is the sapwood, no sapwood = virtually no fluid uptake except a bit up the end grain, what does that mean for fence posts? Well it depends how the posts are arrived at as well as the species, for instance round or half round posts...post material arrived at the sawmill direct from the forest in the form of round material complete with bark, the bark needed to be removed for the treatment process, this was done by stuffing them through a peeler...usually a Cundy, the blades in that machine were set just to take the bark off leaving virtually all the sapwood intact (remember sapwood's the name of the game for chemical retention)

So far so good, round peeled posts full of sapwood stuffed into the Tanalising plant...ideal...Treated round posts come out and get stuffed into the ground, lot's of all round protection.

But then things start to get cheap, if the round post is split we can get two half round posts from each blank, two fence posts from one..yippee..well not quite...suddenly the all round sapwood band has been compromised, there's a flat exposed surface of heartwood, as that stands that surface will not take up any viable amount of fluid.

It gets worse, round smooth uniform posts become all the rage, in many cases due to the nature of round timber most of the sapwood is stripped off when it's stuffed through a rounder....no good...but they stack and look better to most folks!

But it gets worse still, the old method of splitting a roundwood post into two was to stuff it through a band or plate saw, usually a quarter inch kerf at most, if you butt the two halves together it would still be virtually round, not so these days...why... because after its been through a rounder it's easy to take something out of the middle such as a pallet board (pallet boards sell) or a blank for re-sawing into fence panel or trellis battens etc, butt the two halves together...big difference, no longer virtually round...weaker post, so...weaker post with no treated sapwood...no wonder they don't last like the old stuff.

It's a similar story for dimensioned timber posts, the best knot free timber (think £'s) from a well managed forest plantation comes from the outer growth of the tree (knot free growth) this also contains the sapwood, next in value is the rest of the tree (going from outer to inner) eventually you get near to the center where the subsequent cuts will "box" the heartwood, called "boxed heart" this is the crappiest part of the trees timber (very poor £'s), tell you what we'll stuff that out as fence posts...virtually no fluid uptake (more profit) and more shakes/splits than you can a stick at when it starts to dry out.

So...the majority of dimensioned fence post will be boxed heart, here's why, most fencing material for dimensioned posts comes direct from the forest in the form of "fencing bars" a fencing bar is usually 5" to 7" top diameter under bark (TDUB) and 6 or 8 ft in length, in order to make any reasonable money from the log the outer cuts are, where possible cut to pallet board thickness (approx. 18mm) for re-sawing into pallet wood blanks (approx. 100x18mm) or 18mm blanks for re-sawing to fence panel/trellis batten dimensions, that usually accounts for virtually all of the sapwood so very little sapwood is left on the remaining stock which the fence post is cut from, boxed heart will be inevitable from such roundwood.

But...things are looking up a bit, builders merchants etc are now starting to stock dimensioned fence posts that have been incised prior to fluid treatment so at least there's something in the heartwood....Incision was done with the old creosote treated utility poles because brilliant though creosote is, heartwood penetration is very little with any fluid unless assisted.

Species, going back some years there was a lot of pine coming out of the forests, Scots, Corsican, Lodgepole etc, not so now, nearly all Sitka Spruce, excellent strength to weight ratio and a favourite for the pulp mills, but so far as treatment fluid retention goes it doesn't match that of the pines, so there's another factor to consider when taking durability into account.

All in all, generally less sapwood for fluid uptake (crap) and a lot of boxed heart with virtually no fluid uptake for dimensioned posts (double crap)

Unfortunately for the old radio cabinets made of plywood the veneers (except possibly the face veneer) were usually cut from sapwood which is yum yum for the beasties...

Lawrence.

Last edited by ms660; 31st Aug 2017 at 10:56 am.
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