Stability of wire-wool / vinegar finish

[jpa]

Hi, I need to cut some very weathered pine boards for an art project, and am considering using a wire-wool dissolved in vinegar stain, (possibly augmented with strong tea) to help blend in the freshly cut ends so that they aren't too conspicuous.

My question is how colour stable are the results, and are there any longer term problems that one needs to be aware of due to the acidity of this stain? Is it worth trying to neutralise the acidity after staining, with a slightly alkaline solution, of baking soda maybe?

After staining I intend sealing with a semi-matt water based polyurethane varnish, does this sound sensible?

Many thanks!

 

[ED65]

The colour produced by this process is permanent due to the black compound formed by the reaction (iron tannate) being very stable.

I think you will probably need to use some tea to get a strong reaction from pine. Without tea the most I've ever gotten is a weak greying, didn't even make the wood fully grey, but images posted online show that pine/other softwoods will sometimes give a stronger reaction than this so you'll have to see how it goes with your wood.

The tea can be put on after the vinegar solution, it doesn't need to go on before. But I think it's best if the wood is dry before the next thing is applied whichever order you apply them.

You don't generally need to worry about leaving the wood acidic, wood tends to be naturally slightly acid.

If you do want to remove excess acidity though I would rinse with clean water once or twice. If you use a solution of baking soda this could cause an unwanted yellow tinge to appear, which mixed with the black might turn the wood a dingy green.

 

[custard]

and am considering using a wire-wool dissolved in vinegar stain, (possibly augmented with strong tea)

People use tea not because it's the best thing for the job, but because it's the most convenient.

Far better is to keep your eyes open around Oak trees and collect some "Oak Apples" or "Oak Galls", the small shell of a wasp like creature that nests on Oak trees. I find plenty of them while walking my dogs in the forest.

Grind up three or four, soak in half a litre of rainwater or distilled water, filter, add a single drop of washing as a surfactant (otherwise the stain won't penetrate deep into the pores of the wood) and you're done! You'll find this penetrates further and stains much darker and more evenly than with tea.

Even on Oak or Chestnut you need to be careful with the wire wool/vinegar stain, it won't stain the sapwood and sometimes you can have a small sliver of sap left on the workpiece that you didn't notice, so a wash with an Oak Gall solution ensures a uniform and deep black over the entire piece.

Personally I think pieces stained in this way look better with a simple oil finish than with a polyurethane finish, the staining effect is so startling that it can quickly look artificial with a thicker film finish, but that's just my opinion.

I've got a piece of furniture in the workshop at the moment that will have a scorched and wire/wool finish, if I remember I may post a WIP in a few weeks time to show the process in more detail.

Good luck!

 

[jpa]

Thank you both very much!