How to remove water stains from timber?

[SlowFolk]

Hello, 

I currently have a large slab which I’m going to turn into an outdoor breakfast bar, I’m just wondering what’s the best way to remove water stains? 
Cheers! 

[JacobZ]

Hi @SlowFolk,

Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.

My first suggestion is to try using Diggers 2kg Rust And Stain Cleaner to remove the stains. This is an oxalic acid based cleaner that can be used to remove stains in timber, but please note that it is a mild bleaching agent and will change the colour of the timber very slightly.

Please remember to wear gloves, a mask and a long-sleeved work shirt while working with chemicals to avoid any unnecessary harm.

Mix 100g of Diggers Rust & Stain Cleaner in 1 litre of water and mop solution over the entire area. Let soak for a few minutes. Use a stiff brush to scrub the surface and hose off with water.

After using the rust and stain cleaner, I would suggest using a belt sander across the whole slab to remove as much of the stain as possible. Start with an aggressive grit such as 80 and work your way up to 240.

This will remove the top layer of timber revealing the nicer untouched stuff beneath.

Allow me to tag some of our other helpful members to see if they have any ideas, @Jewelleryrescue, @Nailbag, @Dave-1.

Let me know if you have any further questions.

Jacob

[Dave-1]

Morning @SlowFolk 

Woooo thats a decent sized slab of timber! Envy!

I never seem to have a lot of success with using a chemical to get rid of staining. Usually it comes down to elbow grease and more elbow grease.

Id Follow the sanding that @JacobZ has laid out and the timber should come up beautifuly. I would suggest to stain thetimber once you have done the sanding back to keep the natural coluring at its peak.

That must weigh a ton!

Dave

[arfabuck]

For the last 50 years I have used Oxalic acid to remove stains from antique furniture. Years ago making my own but now it is readily available to buy .off the shelf.

Exceptionally good at removing black tannin stains from oak.

It is a natural plant product, so although the term 'Acid' might sound problematic, it is relatively harmless to use. I admit to occasionally washing in the stuff.

It comes as a crystal. Mix with water until all the crystals are dissolved and you have the correct concentration.

Wet the affected area by dabbing a soaked cloth and wait overnight for it to dry.

The crystals will reform, pulling any stain to the surface of the timber, and then just brush it off.

One note of caution though, depending on the timber, it can 'bleach; the surrounding area, so be precise on the application.

Use the standard safety precautions of gloves, mask and glasses.

https://www.bunnings.co.nz/jac-jay-500g-oxalic-acid_p0728384

[SlowFolk]

@JacobZ @arfabuck @Dave-1 Thank you so much for the advice! I will try the oxalic acid & yes it weighs a bloody ton haha. Have a great weekend! 

[JacobZ]

Hi @SlowFolk,

Brilliant!

Let us know how you go and don't forget to share some photos when the project is completed.

Jacob

[Nailbag]

Hi @SlowFolk 

My experience has been that when wood has been water stained that deeply it takes sanding right back as @JacobZ has suggested. If you don't have access to a Belt Sander, a Random Orbit will do the job, just taking longer.

But I think its definitely worth going that Oxalic acid route first @arfabuck suggested, then most likely you will have sanding to do afterwards. Thats when I would highlighly recommend a RO model. These are super efficient and can also get the surface down to a very fine finish which belt sanders can't do.

Nailbag

[arfabuck]

Being an antique furniture restorer by trade, the first commandment is "Do no harm". If you repair/replace something it must remain visible otherwise the value of the piece is greatly reduced. Sanding a defect is a last resort as it removes original timber.

Oxalic acid has been a favoured wood stain remover for centuries as it does not affect the rest of the piece and can be tightly controlled in application. With restoring veneers this is a must do.

On the other hand, it can be injected as deep as you want to go to pull out a deep stain.

Whatever 'stain' the diluted oxalic touches, it will pull to the surface as a crystal, to be wiped away.

Please be aware that it is a natural plant product for natural stains. It will not work on oils or grease..You need methylated spirits for that.

[Nailbag]

Awesome tip @arfabuck I had no idea how effective this product was and will definitely be bookmarking your advice.

Regards, Nailbag