steel wool and vinegar

Discussion in 'Woodturning Discussion Forum' started by Max Taylor, Jan 13, 2008.

  1. Max Taylor

    Max Taylor In Memoriam

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    I know you soak steel wool in vinegar for a different effect. What I want to know is:how long to soak, do you shake the mix intermittently while it is "cooking", and do you vent the soaking while "cooking"? mANY THANKS, mAX
     
  2. odie

    odie

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    For the benefit of those of us who don't know what the heck you're talking about........what effect?

    otis of cologne
     
  3. Steve Worcester

    Steve Worcester Admin Emeritus

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    It is for ebonizing woods with high tanin content.

    I leave it to soak until is is disinegratred, but I have better esults with dyes.
     
  4. Bob Chapman

    Bob Chapman

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    You’re joking…Steel wool and Vinegar?

    If ever there was certain evidence that woodturning is an ancient art, the use of this witches’ brew for staining oak black must be it.

    It works – there’s no denying that, but there is a quicker, simpler and cleaner method of achieving exactly the same result, so why not give it a try? But first…a chemistry lesson.

    Everyone knows that vinegar is a very dilute solution of acetic acid (which is itself a very weak acid) and that steel is mostly iron. When steel wool is placed in vinegar a chemical reaction takes place:

    Iron + acetic acid → iron acetate + hydrogen gas

    It is the iron acetate that is wanted. This is what turns the oak black but, because the vinegar actually contains very little acetic acid, the reaction is slow and we get very little of the iron acetate. Instead, other (unwanted) reactions take place. In particular, most of the iron simply rusts, making the whole mixture into a filthy black mess which contains hardly any of the iron acetate we set out to obtain. Incidentally, the hydrogen gas is also produced in tiny amounts and probably goes unnoticed although you might see a few tiny bubbles on the steel wool in the first half-hour or so.

    Bear with me, please, while I take the lesson a shade further. When metals (e.g. iron) react with acids (e.g. vinegar) the atoms change slightly and become a different particle called an ion. Iron acetate consists of two ions, as its name implies. These are iron ions (from the iron atoms in the steel wool) and acetate ions from the acetic acid in the vinegar.

    End of chemistry, the rest is common sense (or ‘logic’ as we scientists like to call it). We know that vinegar alone does not stain oak black. Therefore it is not the acetate ions which do the staining. Therefore it must be the iron ions. Therefore anything which contains iron ions would be able to stain oak black. So why mess about with steel wool and vinegar for heaven’s sake?

    There is a simple, clean, cheap and virtually harmless iron compound available. It is correctly called Iron(II) sulphate but is commonly known as ‘ferrous sulphate’. It is usually found in the form of pale green crystals which look very much like green sugar. Ferrous sulphate is the active ingredient in some moss killers and in iron tablets (for anaemia). It's available in the UK at places that sell garden chemicals - I guess the USA has similar stores. It isn't very expensive here.

    Dissolving a teaspoonful or two of ferrous sulphate in a cupful of warm water will give a pale greenish yellow solution which will turn oak black if you paint it on, or make you very very constipated indeed if you drank it, or kill the moss on your lawn if you spray it on. I said it was virtually harmless and it is – but you wouldn’t want to drink it any more than you’d drink the steel wool/vinegar mixture. Normal care should be taken and is all that is required.

    Sand your work to its final finish before applying the solution. Be warned that the effect is not instantaneous. You paint it on and nothing happens…the black colour gradually develops over the next couple of hours. It’s probably best left overnight. The water will raise the grain so sand down gently – the beauty is not much more than skin deep. You can repeat the application but the left-over solution will gradually ‘go off’ after a few days. Best use what’s left to kill moss on lawns/paths, and make it up fresh as required.

    By the way, as if you care, I’m pretty sure the blackening is caused by another chemical reaction between the iron ions and the tannic acid in the timber (not just oak). I got a strong black colour when I added a few crystals to some cold tea. I’m guessing that ferrous tannate is an insoluble black substance. Just don’t drink the tea afterwards!

    Bob
     
  5. laymarcrafts

    laymarcrafts

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    As Bob pointed out with the Vinegar-Steel Wool Cocktail you will also produce Hydrogen, therefore you must have an open container otherwise you are likely to have the contents spread across your Workshop and therefore any Steel showered with Vinegar will go Rusty.

    This is not only a Fact, I have photos of my Workshop Disaster to prove it.

    Richard
    http://www.laymar-crafts.co.uk
     
  6. Bill Boehme

    Bill Boehme Administrator Staff Member

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    See the latest issue of WOOD Magazine for a short article about it. It depends on how dark you want the wood to be, but a week is satisfactory for light staining. BTW, this is not a stain in the conventional sense because the solution that you make up will not be dark(it may look more like weak tea or even lemonade), but when it chemically reacts with the tannin in the wood, a dark color is created that penetrates fairly deeply as opposed to stains which sit on the surface. It has a big advantage over conventional stains in that it does not produce a blotchy finish. It is a fairly old practice, but not very well known. Its downside is that you have to wait a couple weeks for the wood to dry after getting it thoroughly wet with the solution before applying a finish, so it doesn't fit in with the modern get-it-done-quickly methods of finishing.

    BTW, Bob Chapman, if you read the articled, they take care of the rust problem through two layers of filtration and the final solution is actually quite clear.
     
    Last edited: Jan 13, 2008
  7. Ron Sardo

    Ron Sardo Guest

    I've been using vinegar and steel wool solution for years. I have a jar filled with the mixture when it runs low I add more vinegar, once in a while I'll throw in some steel wool.

    I always keep the jar closed and I've never had a problem with my tools rusting.

    Here is what I do when I want a really dark ebony effect.

    I paint on some strong tea or coffee and let it soak in and when dry I sand smooth. (I'm raising the grain and adding tannin into the wood).

    I apply the vinegar/steel wool mixture.

    Sometimes, depending on the wood, I need to do this twice.

    The "stain" is really not very deep, so be careful with your sanding.
     
  8. Bob Chapman

    Bob Chapman

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    Ron, what a simple idea, but pure genius - don't just paint on the iron, paint on the tannin first! I assume that this method would work on any timber. have you tried it on many different woods?

    Bob
     
  9. Ron Sardo

    Ron Sardo Guest

    90% of the time I'm using maple or walnut when I'm ebonizing wood.

    I've tried it on oak, poplar, cedar, cherry and holly with good results

    Back in the day of very dark oak furniture, asphalt was the key ingredient to getting oak black. It was a very closely held secret for decades.
     
    Last edited by a moderator: Jan 13, 2008
  10. Duane

    Duane

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    Vinegar and steelwool.

    You guys have missed something. I have been working on a different staining method. Rough turn a hollow vessel from wet wood. End grain works best. The walls should be about 3/4" thick. While its still wet stuff it full of the cheapest steel wool you can find. Then fill it with vinegar. Set it on a rack over a bucket to catch the drippings.Pour the dripings back into the vessel 2or 3 times a day. Make sure the wood does not dry and crack and do not use the drippings to paint the outside of the vessel. Ok some of the steel will rust. That is a good thing. The rust color will shoot through the wood to, in spots. Colors that you can't get with an airbrush or any other method.. Allow the stain to soak through from the inside out. After 2 to 4 days dump the mess out and wash the inside out with water. Now treat like any other wet turned vessel. When the wood is dry return and sand the vessel like any other.
    The end grain will be coal black, the side grain will have little or no stain at all. The stain will shoot through in some places but not others. Leaving a very natural look. Very much like spalted wood. Have you ever cut a tree that has steel in it such as fence wire or steel post. The steel stain is carried up the tree trunk and stains the wood black but only rite above and below the steel. It is very much like spalted wood only more of it.
    Try it, you might like it. It is a bit messy so use gloves and be carefull.
    And above all else have fun with it.
    Duane
     

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