best finish for spotted gum/ironbark

[jane123]

I have just had a hefty outdoor table constructed. It is made from both spotted gum and ironbark. I am seeking advice as to which oil, tung, linseed, etc., is the best finish. The table will be outdoor fully exposed to the harsh Queensland environment. Thank you.

[strangerep]

I have just had a hefty outdoor table constructed. It is made from both spotted gum and ironbark. I am seeking advice as to which oil, tung, linseed, etc., is the best finish. The table will be outdoor fully exposed to the harsh Queensland environment.

Fully exposed? Then basically, you're stuffed -- if you want a natural-looking timber finish.
None of the ordinary products last too long. Spa-n-Deck is the longest lasting that I've tried, but that's still only less than a year before it starts
to look disappointing. Much better than many oils though.
It'll last a few years before recoating is absolutely necessary.

2-pack marine-grade varnishes (e.g., International's "Everdure"
epoxy sealer and "Perfection" varnishes last about 3-4 years and
still look good (if you give enough coats to begin with, and don't
faint when you see the price), but then you've got to sand them
down and re-coat.

Unless you're in love with re-varnishing timber every few years,
think about paint instead...

[jane123]

Thank you Strangerep for your response to my query. I think I will stick with the oiled finish and use the finish you recommend. I don't really mind reoiling annually (well, I say that now, but it is surprising how quickly the next oiling comes up). I will purchase a cover and keep the table covered when not in use. That should make the oil last quite a bit longer as well as provide general protection. Thanks heaps. Jane

[strangerep]

I think I will stick with the oiled finish and use the finish you recommend.

Er,... which one? The Spa-n-Deck (which is acryllic, not oil),
or the marine-grade products (which are spirit-based)?

I don't really mind reoiling annually (well, I say that now, but it is surprising how quickly the next oiling comes up).

The disappointment comes when you how much tannin is leaching
out during that time. Much cleaning is needed (bleach, napisan,
oxalic,...).

(BTW, when you're doing it the first time, make sure to give it serious
cleaning with napisan, then oxalic. Have a look at the "deck" forum
over in the renovation forum -- it has instructions about how to prepare
outdoor timber for this sort of thing.)

I will purchase a cover and keep the table covered when not in use. That should make the oil last quite a bit longer as well as provide general protection.

Yep -- if you can get a cover which is both fully waterproof and
also opaque enough to totally block out the UV rays, that'll help a lot.

[Stewey]

I've used Feast Watson exterior UV-stable varnish - I like it-but I'll give a big thumbs-up to the Epidure product in preference. It IS good.

[jane123]

Once again, thank you so much for your advice. I wouldn't have even thought of cleaning it first. Not that I am one to go the 'near enough is good enough route', just that I didn't know it was necessary. I am currently sanding the table from its rough hewn state (just milled I guess, with the marks of the circular saw or whatever is used in the milling process). Can I ask one more bit of advice: up to what grit should I sand it? Thankv you.

[Dengue]

Sikkens products are the only ones that work in this situation. They are specially formulated for UV protection. I put them on my west facing front door in the hot tropics.

[strangerep]

Sikkens products are the only ones that work in this situation. They are specially formulated for UV protection. I put them on my west facing front door in the hot tropics.

Maybe this shows there's a significant difference between a vertical
surface (where water can run off easily) compared to a horizontal
surface (where it can't).

Before adopting the 2-pack marine stuff, I did a test with Sikkens
stuff. I spoke at length with someone on the Sikkens technical help
line, and gave blackbutt samples 3 coats of HLS and whatever his
recommended procedure was for preparing it. Then I left them
outside in full exposure. Within 3 months I could detect signs of
deterioration. After 6 months it looked bad and the surface was
starting to split/crack and tannin was leaching up quite a bit. After
12 months it looked awful and after 18 months I gave up on the
test as a joke and threw it out.

The 2-pack marine products are vastly superior (as they ought to
be for the price). Absolutely no tanning bleeding or other
deterioration of the timber even after several years. But the coating
began to show very faint signs of deterioration after 4 years so
I sanded it back a little and gave two more coats. The appearance
of this product is stunningly beautiful, but none of these lovely
things last forever under full (horizontal) exposure.

I took the moral of this story to be that the marketing terms
"UV-protection" and "UV-resistance" are a long way from "UV-proof".

[strangerep]

Once again, thank you so much for your advice.

You're welcome. (I love chatting about this sort of stuff... )

I wouldn't have even thought of cleaning it first. Not that I am one
to go the 'near enough is good enough route', just that I didn't know it was
necessary. I am currently sanding the table from its rough hewn state (just
milled I guess, with the marks of the circular saw or whatever is used in the
milling process). Can I ask one more bit of advice: up to what grit should I
sand it?

Since you're starting from a rough state, I should warn you about
some other matters first...

After each grit one would usually wet the piece down to make the newly
sanded fibres stand up a bit (since that's what will happen anyway when
you apply a finish). It can be a bit disconcerting when you feel how
rough it becomes after the wetting down. For an indoor piece, one would
apply sanding sealer between each grit. E.g., 120 grit, then sealer,
then 150 grit, then more sealer, etc, etc. This kinda gradually
counteracts the stand-up effect of putting the final finish on.

But sanding sealers are only rated for interior use (as far as I know).
So you have some decisions to make on how much work you want to put
into the project...

One approach is merely to wet the timber down between grits and rely on
the next higher grit to remove the roughness. Then when you get up to
(say) 180 grit, start using the finishing varnish (or whatever) as a
substitute for the sealer, and continue sanding honestly between coats
until you get up to around 300 grit. For an exterior piece I doubt that
going to even higher grits is justified and maybe even 300 is too high.
Then do some more top coats with very light sanding in between (just to
take the tips off).

The trouble with the above is this question: "at what point should one
clean the timber thoroughly?" -- which involves very heavy wetting of
the timber and hence makes the fibres stand up a lot. I eventually
reached the conclusion to sand up to about 150 grit, then clean
thoroughly (and I do mean "thoroughly" -- using the several products I
mentioned above), then continue with 180 grit and higher using the
varnish or whatever as a sanding sealer.

If/when I do something like this again, I think I'll use the Everdure
as a sanding sealer, even though it's expensive and time-consuming
since each application needs several days to cure sufficiently.
But hey, it's fun if one has the time. (Sad, huh?)

Anyway, this might all be too much overkill -- only you can decide
that. Do you have any offcuts of the timber? If so, it might be
advisable to keep your table fully under cover until you have time to
try out some of the above techniques on the offcuts before tackling the
table? That will also give you more reliable understanding on how much
work is involved with different strategies...

Cheers.

[Stewey]

I'm a signwriter, but have restored lots of horse-drawn vehicles, and striped a fair few vintage cars.
I used to use Feast Watson UV-stable high gloss exterior varnish, or their spa marine varnish, and like those products, but the Spa/marine stuff is sticky & slow-drying.
Sanding sealer use must be minimal if the stuff is going outside, or the varnish will delaminate at the junction with the sanding sealer.

Two clients have done-up veteran cars, and wanted the old wooden spokes 'varnished' and used the Epidure clear on the spokes.
I then striped over that in enamels.

The Epidure clear looks stuck-on as well today as ten years ago, and those spokes have taken a fair pounding. Admittedly it hasn't been 10 years in full Aussie sun, but it's been a harder life, compression-wise than any furniture will get, and they held up better than any other product I know.

The alternative might be to try 2-pack automotive clear urethane,,,but I wouldn't. It's good stuff, but poisinous to apply & brittle when set - not recommended for timber where you might expect some movement or flex.

[strangerep]

Two clients have done-up veteran cars, and wanted the old wooden spokes 'varnished' and used the Epidure clear on the spokes.
I then striped over that in enamels.

The Epidure clear looks stuck-on as well today as ten years ago, and those spokes have taken a fair pounding. Admittedly it hasn't been 10 years in full Aussie sun, but it's been a harder life, compression-wise than any furniture will get, and they held up better than any other product I know.

Interesting. BTW, I just checked the label on my tin and it says "Everdure", not "Epidure". Are we talking about the same thing?

https://www.whitworths.com.au/main_i...bsolutePage=13

[Stewey]

Sorry-my error-I just checked the label they gave me-it's Everdure.
Like this:
https://www.whitworths.com.au/main_i...bsolutePage=13