How best to stabilise rotted oak?

[biffvernon]

Probably. Perhaps because I happen to have a large bucket of Cascamite and I don't happen to have any Bencon 20 epoxy consolidant. It's also probably cheaper. I'm assuming this is not some priceless historic monument. The basic principle is that, in a situation where the wood is about to crumble to dust and be gone, glueing it all together with either an epoxy or a urea-formaldehyde resin so that it become fairly indestructible, may be the best option.

 

[Penners]

OK, thanks for that. Priceless historic monument - no. But very nice GII listed building* - yes.


*Sorry - 'Heritage Asset'. :roll:

 

[88v8]

Any further views on this as regards resin?

Bought some lovely, well they were, once, coach house doors. A pair, each 78" x 44". Some moron left them outdoors until they got damp and the death-watch got into them. And then wrapped them in black shrink-wrap, perhaps with the best of intentions, which I unknowingly left on there for more than three years.
The beetle, secure in their warm, damp, environment, chomped mightily. When I unwrapped them, sooooo much frass. It looked as if someone had murdered a Teddy bear in there.
A heart-sinking moment.

So now the bottoms - which will in future have to be the tops - are chewed to bits and not an easy repair.
They are going to be one pair of the doors in my new garage.

They were so well made they didn't even have or need diagonal bracers.



They have handmade hinges with handmade coach bolts. Or rather, they had. I'm going to hang them on Collinge's, which is another pile of work as the pivots have to be recessed into the oak frames.
The olde bolts:



I already cut out the ends of the wormed frame members to splice in new pieces, but was thinking to use the Bencon 23 to 'repair' the tg boards. Not these boards, too far gone, but some of the others are less noshed.
To give some perspective, those are 7" boards.



What do we think?

Ivor

PS current link to Bencon/Benring
http://www.benring.co.uk/

PPS Nice to be reminded of Middi, in a sad way.

 

[livias]

It doesn't hurt to get another suggestion ... I'd use limewater. I've used it very successfully to consolidate fragile old oak

 

[88v8]

Good heavens. So, it sort of turns the oak to stone. Fossilisation. Would it be stable outdoors, temperature & moisture change?

Ivor

 

[livias]

I don't know if it would work in an exposed location though i have my doubts but Penners oak is to be protected behind secondary glazing so is not going to suffer from active weathering. I successfully used the technique in my shower room so it can certainly cope with temperature moisture and humidity changes. I don't make a habit of bashing into the timber but it is now robust enough to take the occasional knock. BTW It is a reconised conservation technique, not just one dreamed up by me :mrgreen:

 

[noj]

I don't know if cellulose could work - good old fashioned 'dope' - put back a naturally derived substance that's rotted away? Guess it could just make it look varnished though...

Tung oil (which hardens well) could help too - but would darken everything to an extent

 

[Zebra]

Oh dear, 88v8, what an awful discovery. They are awfully damaged, aren't they. I do hope you manage to find a solution.

 

[Juju]

How funny Mr P - I came on to the forum today after a very long absence to ask a very similar question! We're having our little probably original 17th century window repaired to our cellar. The Joiner and carpenter made some suggestions on stabilising it with wood hardener etc and I'll be checking with my very knowledgeable SPAB colleagues when I'm there next week. However, lots of useful advice here already. By the way, you don't need to be a SPAB member to use their technical advice line.

I'm keeping (obviously) all the wood frame that we can but the bottom bit is quite crumbly. We're fitting timber windows into the frame - on one side it'll be a fixed unit and on the other side an opening one. I don't think ours has ever been painted so I'm just debating that - all the other windows are painted. I suspect the cellar window hasn't been used as a window for donkey's years(it's part boarded up/chicken wire all over it) as it had an old lean-to covering it for years housing the only toilet in the property and then that was knocked down and an ugly lean-to rebuilt. We've now knocked that down!

Juju

 

[Juju]

I've just noticed how old the original post was on this! Did you get the window sorted Mr P?

Juju

 

[Toby Newell]

If you look there are two main types of wood stabiliser resin

1. Single pack
2. Two pack

The single pack dries via solvent evaporation, the two pack cures via catalyst reaction and is far more durable.

You can inject these via hyper dermic needles (you will need a few!) the problem with verticals is that you will need to stop the resin from egressing the interstices before it cures (from a few minutes to over 10 minutes depending upon the ambient temp)

The problem with this is fabricating tons of mini shuttering with hardboard or applying duct tape (which may damage the surface of friable surfaces when removed)

beeswax would be even more difficult to introduce and have possibly an order of magnitude (or maybe even more) less structural integrity.

Needless to say the resins (both types) are expensive and unpleasant to use.

You can get clear resins and you can even self colour them with pigments or universal stainers without much loss in engineering strength or durability.

Edit:

Technically looking at the extreme friability and hollow honeycomb effect nature of the timber in the pictures a two or more stage process would be involved, the first being a thinner penetrating epoxy resin that soaks in and stabilises the substrate forming a solid but still porous matrix, then secondly a thicker (maybe mixed with compatible wood dust and / or self coloured pigments for extra body and aesthetics) epoxy coat that would fill the interstices and build structural integrity and develop load bearing capabilities again to the member. Whilst the first thinner epoxy step may be completed in one go the application of the thicker epoxy resin / colour / sawdust mix may require several passes, this is especially true in high ambient temperature conditions as some resins can go off very quickly.

As a general rule adding less catalyst will prolong the curing time and give rise to a stronger overall cured epoxy, but lead to problems of slump and waste (as resin is less viscous)
Adding more catalyst will shorten the curing time which may reduce slump and the number of filling operations required (and save on material volume used too) but will lead to a slightly weaker epoxy.

Overal I favour using more catalyst and working faster. Either way it's a messy job. A proper organic fume respirator is a must even in the open air, as are a ready supply of nitrile gloves and disposable overalls.

 

[88v8]

If you look there are two main types of wood stabiliser resin.....

Thankyou.
I've finished repairing the frame of the first door.
The Bencon resin arrived for permeating the tg boards.
Their MD advised using Contiboard as shutter, with several coats of polish as a release agent. He reckons it takes over an hour to go off.
I can see it's going to be a fiddly job.

Ivor