Restoring weathered slab

Hi all, pardon my ignorance, and possible naivety around this subject as I am very new to all of this.

I have a very old weathered slab left of my property by the previous owner. Unsure what type of wood it actually is but it would have come from one of the gums on my property back when it was being cleared, it's about 3.5m long and 1m wide and 10cm thick. Structurally it's still in very good nick, no warping at all.

I want to use as an outdoor (undercover) table, and curious how I treat the top of it as in how I finish it, or is there a coating I can apply to smooth it all out. It currently has many little cracks and fissures on the top, and have no clue where to start other than sanding it back.

Attachment 535648

the only type of fill you'd be able to put in there would be a 2 part epoxy. but you'd have to fill it and then sand off all the excess.


at 100mm thick i'd just take it somewhere with a flattening jig/router and get them to take the top layer off to get to the nice fresh wood inside

Quote:

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Originally Posted by cbates

... it's about 3.5m long and 1m wide and 10cm thick.

Structurally it's still in very good nick, no warping at all.



Attachment 535648

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Attachment 535739 Attachment 535740


First, cbates, welcome to the Forum.

First, could you confirm the dimensions and the condition of your plank. From your photo, seemingly:

• It appears to be less than 1 metre wide,
• It appears to be less that 100 mm (4")thick,
• It appears there is significant twist over its length,
• Weathering seems quite deep,
• It appears the some holes are significant,
• There may be splitting near the ends.

You infer that you have limited experience. What tools do you have or have access to - both hand and electric?

Finally, have you given any thought to the legs?

I ask these questions because nothing will stick, other than for a very short term, to weathered timber.

Hi Graeme,

Yes you've caught me out on my terrible measurements.

It's just shy of 600mm wide, and 70mm thick.
It is indeed very deeply weathered, and there are some significant holes.

Now in saying that, I understand I will never get a good grain out of, and I will cut off the ends to tidy them up, most likely removing the holes. Despite the weathering it is still very solid.

I'm not concerned with having the most beautiful table top, I merely want to make it useable (comfortable). Tool wise, I've got a belt and orbital sander, drop saw, festool rail saw, compound saw. If I don't have something, a neighbour will.

As for legs, I've got a pretty big stump lined up, sort of like how it sits now. Like I said above, I'm not terribly concerned about longevity. Once it passes it's prime it will go in the fire pit and I'll source something else.

All good. I will answer this is two parts:

1. Renovating the top, and
2. Assembling the table.

Rustic, usable and a great conversation piece, it will be. The problems are twofold:

• No glue will stick permanently to the grey weathered wood, we need clean surfaces, and
• How extensive is the cracking; will it grow and split the slab?

Sanding: With a very course grit belt - say 40, or 60 grit - san the top, bottom and both sides of the slab to remove all grey material except in the holes and cracks. Do not do the ends as the end grain may be fragile with all that cracking.
Repeat with course belt - say 80 or 100 grit - to remove previous sanding marks.

Reinforcing: You will need two hardwood battens, each 600 mm long, and from 15 to 30 mm thick and from 25 to 100 mm wide - whatever you have. Dress all four sides. Cut trenches 75 - 100 mm from each end on the bottom of the slab and epoxy in the reinforcing battens. [This controls future splitting.] If wood in trench is crap, cut off slab at this point and restart reinforcing step. Add a third batten in the middle of the slab if you are worried.

Holes: With a sharp tool, poke around each hole to determine where good timber starts. Cut a batten the length and width of the "bad timber" and from 15 to 25 mm thick. Trace out the edges of this batten over the hole, carefully route it out and epoxy the batten into the hole. Shipwrights call these plugs dutchmen.

Cracks: With whatever tools you have or can improvise, scrape out as much grey matter as feasible from the cracks - tedious, but necessary. Improvised tools might include sandpaper wrapped around 150 mm steel ruler, tang of triangular file heat bent 90°. A friend does this and the initial sanding (above) with a Karcher pressure washer, but I have suffed up every time I've tried.

Final Sanding: When totally dry, including in all cracks, resand to fare in all plugs and then final sand with the random orbital sander through the grits - 100, 150, 200.

Vacuum: Vacuum carefully to remove all dust, top and bottom, concentrating on cracks.

Epoxy: Dilute some epoxy with about one third acetone or MEK; paint it slowly over all surfaces, concentrating on cracks. Diluted epoxy penetrates into the grain better; slowness stops bubbles forming. Repeat twice.

Thicken some epoxy - I prefer colloidal silica - WEST System #406 - to resember cream and paint into holes, layering up until just above wood surface. More reliable than trying to do it in one go. You only have to wait 1-2 hours between applications, unless it is cold.

Repeat on bottom.

Finish: Allow epoxy to cure for at least a week, sand with 120-150 grit and apply two coats of polyurethane - Estapol.

There are lots of approches to this.

With a single log in the middle, there will be a lot of forces operating - like a see-saw - so it might not be sufficiently rigid or stable. Two possible options:

• Put a log at each end - easiest.
• Reinforce it.

Get a stud, approx 100 x 50 and from 1500 to 2000 mm long. Route a trench across top of stump/log about 80 mm deep, like this:

Attachment 535847

Then screw or epoxy the stud into that trench.

Attachment 535848

Measure the height of the stud protruding above the stump and route a trench that deep in the slab. Place the slab over the stud, and fasten.

If table still too unstable then build stabilising feet. Route longitudinal and cross trenches the depth of the stud in the bottom of the stump and insert two studs. In my view they should extend about 500 mm longitudinally and about 300 mm laterally. The finished result should look like this. You can round corners, as required.

Attachment 535849

I guess I would ask: Is this to be an indoor table or outdoor table.

Many (most) clear epoxies aren't good finishes when used outdoors, especially when exposed to the elements. Remember that wood swells and shrinks (A Lot) with changing humidity, and especially rain. That causes cracks. Also, clear epoxies tend to yellow with UV contact, and they often get hazy with extended time outdoors.

Typical outdoor finishes are extremely flexible (read mushy.) The clear ones (such as spar varnish) require reapplication every year or two to maintain the beauty. If you don't strip and reapply frequently, they tend crack as well as to look hazy and clumpy.

Indoor... The only thing I would add to the advice you already have is to check it for bugs, especially the wood infestation types. There are plenty of critters which are better off when left outdoors.

Thanks Graeme,

Very thorough and a great guide for getting started!

The benefit of this it's a good trial and error, I'm not bothered about messing it up. It's a good first slab!

Regarding the legs, the stump I have is big enough to cut it half lengthwise and put one on each end, that is the plan at least.

@truckjohn, the table will live outdoors, but under cover.

One final question, is it better to cut it to size before or after working on it? I'm guessing it's much of a muchness.