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iron and tannin

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marcros

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Rather than corrupt another thread, I thought that I would start a new one.

I am going to be building a chestnut outdoor table. The fixings can be brass or stainless, but it will have forged steel legs, and steel channel inset into the underside. I haven't used chestnut before but I believe that it is high in tannin.

What can I do to prevent staining, will painting every part of the channel (including bolt/screw holes) be sufficient? In theory it should be dry when complete because it will be under the table top.

for the legs, will a stainless washer work between the steel and the wood- using the stainless or brass fixing.

how were oak church doors protected, back in history?
 

Phil Pascoe

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If you mix s/s and galvanised fittings, you'll get a reaction that strips the galvanise which then allows the steel to rust. It does take quite a long time, though.
 

MikeG.

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marcros":2onp88le said:
..........how were oak church doors protected, back in history?
They weren't. One of the reasons they are the colour they are now is that the iron created dark stains down the door. Being out in the weather strips oak (and chestnut) of its tannins. It washes out and stains the ground or building materials below, so the "problem" (in the right circumstances I see it as a bonus, not a problem) goes away once the oak is dry and tannin-free.
 

Fitzroy

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Aye, I’ve just learnt the hard way about the rain washing the tannin out.

I made a replacement roof window that I’ve never got round to fixing a opener on so it gets propped open with a chuck of oak. It rained the other night and the rain soaked down the oak and dripped down the wall. Another job for the todo list.

9674E529-2C30-4E4B-B1F5-BEFAF3D08AAF.jpeg


More on topic I built an oak garden table 5 years back. The top is held on with lag bolts from underneath. Top is about 65mm deep, from memory lag bolts go in 40mm. No staining to be seen yet.
3B1933DD-B8BD-42F2-BA94-B0AAC83F9A07.jpeg

CF5A1F1D-A1B2-4A05-BCE3-160F495CB9D2.jpeg


Parts were all given two coats of OSMO uv protection oil before assembly. Underside and legs have fared well. Top surface has been ravaged by 4 summers and winters to a beautiful silver.

Sorry for picture orientation, stupid iPhone!

Fitz.
 

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