External Stained Oak Bleeding - prevention?

[RodW1]

An oak timber balcony which is stained dark (not by me, probably at least 8 years ago), in wet weather appears to bleed onto a newly laid patio, which is discolouring the grout. The colouration of the grout can be removed with brick acid successfully but I want to prevent the bleeding.

I'm not sure if this is the stain itself coming out, or tannin.

I was thinking of putting some Thompson's Water Seal over the whole balcony, but now I'm not sure if the better choice is to prime it and paint it instead.

Any advice welcome!

 

[Deleted member 174758]

Are there any steel nails or screws used to fix the oak in place? The problem with oak is that it contains considerable amounts of both tannin and acetic compounds, both of which combine with water to produce tannic acid and acetic acid respectively. Whilst these by-products by themselves are more or less clear, they will both react with ferrous metals to form a black, semi-indellible rust. This is presumably the staining you are talking about. So you need to check for the presence of nails or screws used to fix the oak in place, remove them and replace with stainless steel or brass equivalents. Painting over it won't stop it producing stain, it will merely slow it down a bit

BTW you might find that oxallic acid crystals (available from chemists, aquatics suppliers, Amazon, etc) mixed with water is a safer way to remove the stains than brick acid (which is actually muriatic acid) and is a lot less hazardous to handle

 

[RodW1]

Thanks so much for the response @JobAndKnock I really appreciate it.

That is a very good point re: nails/screws. I hadn't actually considered it could be rust running from somewhere. I'll get up on the balcony later today and check any of the screws which I can find to see if there are any culprits.

Just to confirm, do you think it is unlikely to be the stain itself in the wood which is running and causing the issue?

 

[Deleted member 174758]

After 8 years I doubt that any stain would still be bleeding. However, if the timber is oak, then black rust is highly likely if it wasn't installed with stainless nails or screws. It is a common installation error.