Ebonised oak and UV light

UKworkshop.co.uk

Help Support UKworkshop.co.uk:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

marcros

Established Member
Joined
11 Feb 2011
Messages
11,302
Reaction score
745
Location
Leeds
If I ebonised oak, using vinegar and steel wool and then use several coats of tung oil on top, what will happen after 6-12 months outside? I am aware that tung offers no UV protection.
 
The black at least you don't have to worry about, the reaction creates iron tannate which is a stable black compound.
 
Tung oil outside? Not sure thats such a good idea; won't keep water out for long. As to bleaching with the uv I couldn't say but suspect water will do the damage before you have to worry about the sun.
 
That's an interesting question.

Here's a test piece I did several years ago ahead of using this finish on furniture, it's scorched and iron stained Oak with a couple of coats of Osmo PolyX, and this is what it looks like now.

Oak-Iron-Stain-01.jpg


Besides several years of oxidisation it's also been stood in a south facing window. Despite that there's no evidence of any fading at all, it's still a solid jet black.

That's pretty encouraging, but it doesn't really answer your question. The hammering a finish receives outdoors absolutely dwarfs any punishment this test piece has received. I think Mr Bartlett is on the right track when he talks about repeated cycles of rain and sun. Here's where I cross cut this test piece to get a sense of the penetration achieved with iron staining.

Oak-Iron-Stain-02.jpg


As you can see it's the merest fraction of a millimetre, and that's with multiple coats of all the staining solutions. It's easy to see how that might leach out of the timber when exposed to real weather!

Plus you've got the realities of any oil finish outdoors, unless it's to become food for microbes it'll need to be abraded off and replaced every year or so. So how will that wafer thin layer of iron staining resist repeated sandings?

I'd really like to know the answer to your question, so I hope someone gives it a go and reports back with their practical, first hand experiences.
 

Attachments

  • Oak-Iron-Stain-01.jpg
    Oak-Iron-Stain-01.jpg
    60.9 KB · Views: 243
  • Oak-Iron-Stain-02.jpg
    Oak-Iron-Stain-02.jpg
    75.7 KB · Views: 242
I use the Vinegar and wire wool trick to stain and it works great.

I usually use 000 wool and white vinegar, break the wool into small pieces and put into a jar, Don't cram it in. Fill to the top with White Vinegar ( I use a 12% one so it is slightly weaker but very cheap. ) Give the jar a really good shake and pierce a small hole in the lid. Try not to make the hole too big or leave the lid off as you will have vinegar odours everywhere. Leave it for anything from 24 to 72 hours, the time spam will be up to individual choice, experiment on off cuts until you reach the shade you are happy with. It is VERY important that you filter it when switching it to a different jar, DO NOT keep it in the same jar. The reason for the filtering is so there are no minuscule wire wool bits going onto your project they are a nightmare to rid, worse when they start rusting.

When you have the desired shade (anything from a nice golden shade to a jet black) paint it on as soon as you can, if you leave it for a day it will come out differently to the shade you liked. Once on give it a light sanding and paint a second coat on it. It won't really alter the shad putting numerous coats on unless you leave it too long.

Contrary to popular belief you can leave what is left over in a jar, there is no need to throw it away. It will look like a rusty water colour and you would be thinking it an awful colour, ( it does look bad, ) but if you want a really dark black and have the wood take on an ebony look then use this. Personally I very rarely let the wool soak in the vinegar for more than 24 hours, that way I can get most shades I am after and I am able to re-use the wire wool when making a new batch.

So far I have only ever used it for things indoors, i just pop a sealant on it and varnish in the normal way, I would think that for outside you would just need to treat it in the same way as you would for any outside projects.

Gary
 
Garno, my experience seems to differ from yours. I find to avoid patchiness it's essential to charge the timber with tannin, this applies just as much to high tannin timbers like Sweet Chestnut or Oak as to low tannin timbers like Pear. You can sometimes get away with it on freshly cut Oak surfaces, but I suspect the tannin starts to evaporate out from the surface layer after just a few days. You can see from my previous photo that you're only really treating a few thou at the very surface. For a tannin solution you can either buy it as a chemical, boil Oak bark and fresh Oak shavings, use strong tea, or my preferred route is to collect Oak galls and crush and boil these. That's how ink used to be made and I find that gives a small edge to the depth of blackness.

Another thing is I sometimes find the surface doesn't actually go black until the surface is either oiled or burnished, it frequently turns a horrible maroon or brown colour first, which might give someone a scare if they've never done the job before! On very open grained timbers like Oak a single drop of washing up liquid is useful as a surfactant to break surface tension and get the solutions deep into the pores.
 
Just as an aside I was reading somewhere the other day that the Japanese use tung oil as a timber preservative for outdoor timbers. Now, I don't know the details. They may soak the timber in a bath of oil for a month for all I know, but it is suggestive of tung oil at least having the potential to be a useful preservative for exposed timber.
 
Very strange indeed Custard.
Fortunately I have never had a problem with patches appearing, I have never yet managed to get away with just using the one coating. Once I have sanded it does show that some areas are better than others but I just slap another coat on it until it stops bringing up any rough bits.

I obviously do not use it on projects that need to be perfect as you guys do, just because I have not yet got the confidence to start one, Still very new to all of this. What size wire wool do you use and what is the vinegar concentrate percentage? as I have heard that it does make huge differences.

Gary
 
He said - I use a 12% one so it is slightly weaker but very cheap. I think this unlikely as it's usually 5% - 6% acid, in fact I bought some without looking that was only 4%. By the bye.

OP - have you thought about using ammonia? The colour goes a lot deeper.
 
phil.p":3rdnpxi3 said:
He said - I use a 12% one so it is slightly weaker but very cheap. I think this unlikely as it's usually 5% - 6% acid, in fact I bought some without looking that was only 4%. By the bye.

OP - have you thought about using ammonia? The colour goes a lot deeper.

Whats with that remark? Have I managed to upset you somehow. This is what I got https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1

It is weaker than the standard and this is at least twice the strength you purchased. By the bye.
 
The concentration level of Golden Swan White Vinegar is 5%.

Their info, not mine. I've never seen any bulk vinegar over 6%. You haven't upset me in the least, I just wondered where you got 12% from, you say what you have is weaker than the standard - I wasn't aware there was a standard.
 
phil.p":3muwx84i said:
The concentration level of Golden Swan White Vinegar is 5%.

Their info, not mine. I've never seen any bulk vinegar over 6%. You haven't upset me in the least, I just wondered where you got 12% from, you say what you have is weaker than the standard - I wasn't aware there was a standard.

From a few places, it is a minimum of 5% and reading the comments and watching things on the dreaded You Tube many have tested it to be upto 15%. According to you tube 12% is the lower reading they have for this and say they always go for the 15%, the one I have has been so called tested by a friend who tells me it is around 12%. I will happily tell him he is wrong.

At the end of the day I was only trying to help. Probably the last time I ever will now.
 
Thanks everybody.

This is for a bench that I am constructing for the (my) garden from new oak sleepers. I can leave it to silver unfinished, oil it and do so every year, or I wondered about ebonising. I could fume, but it probably doesn't add anything in terms of protection to simply oiling. I was hoping that somebody would come back and say that the ebonising would stop it going silver and it would be an easy alternative.

I will give the wife the choice. if I have to sand and oil it once a year its isn't a big job. I don't mind it going silver.

I thought that tung was ok for outside, but I will research further if I oil.
 
marcros":2wf44jh2 said:
I thought that tung was ok for outside, but I will research further if I oil.
Well linseed is so tung oil should be!

Tung oil has by all accounts been used for centuries as an exterior finish in China and elsewhere in Asia. But IIRC they don't apply it like we'd oil normally, it's flooded on and not wiped dry.
 

Latest posts

Back
Top