Ask The Expert – Removing Tannin Stains

If you have any questions on vintage furniture renovation, upcycling techniques, or need tips on how to care for you precious piece to keep it in tip-top condition, email your questions to resourcevintage@myresource.org.uk and we’ll do our very best to answer them for you.

stained oakJuliet asks our expert “you mention in your article on renovation that black stains on oak and teak are caused by tannins so would need to be bleached. Do you have a reference for how to do this please?”

Our workshop lead Nick repliesWe use  Rustins wood bleach A + B , which is a two part bleaching kit and can be purchased from Rest Express (online). The product has full instructions and is quite a strong mixture ideal for the problem

*Rustins Wood Bleach –
removes weather stains and discolourations, makes bare wood white or lighter in colour.
Rustin’s two part Wood Bleach is ideal for removing weather stains, ink stains and for lightening natural wood. For instance, mahogany wood can be bleached white then stained to another shade, such as Teak, Oak or Pine, using Rustin’s Wood Dye. If the wood is to be left as light as possible after bleaching, then it should be finished with Rustin’s Clear Acrylic Varnish.
If wood has been recently stained with a solvent-based penetrating wood dye, remove as much of the dye as possible with white spirit, steelwool and rag before bleaching. Rustin’s Wood Bleach will only work on bare wood. All varnish, lacquer or polish must be removed before applying bleach solutions. Old finishes are best removed with Strypit Paint and Varnish Stripper.
Easy Application
Apply solution “A” liberally, by brush, leave for 10-20 mins, the wood may darken at this stage.
Apply solution “B” liberally, using a clean white fibre brush.
Leave for 3-4 hours then wash and neutalise throughly as directed.
Once dry the wood is ready for staining/finishing.
If the wood is very dark or has been badly stained, repeat application after 2 hours i.e re-apply “A” leave for 10-20 mins then re-apply “B”.
After bleaching a crust may form, to remove scrub the wood with clean water.

Neutralising
Generally Wood Bleach is neutralised by washing with a solution of white vinegar, 1 teaspooon of vinegar in 500ml of water.
However there are two exceptions:
If Rustin’s Plastic Coating is to be applied after bleaching, the surface must be washed with a solution of spirits of salts (hydrochloric acid), 1 part spirits of salts to 7 parts water. If a white deposit remains repeat the washing process.
The wood should not be neutralised if acrylic water-based varnishes are to be used after bleaching, thoroughly wash with water only.

*Information from Rustins infosheets on WoodBleach

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About resourcevintage2014

Fabulous Upcycled Midcentury and Vintage Furniture, handfinished by Volunteers and Trainees
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