# Soap turns oak soap dish black



## magician (Jul 29, 2014)

I made my first batch of soap ever 4 weeks ago and was excited about getting to try it today.  It is a simple cold process 100% olive oil soap.  I placed the bar of soap, after using it, on a new oak soap dish and noticed that where the soap touched the wood, it turned blackish.  Is this a problem with the soap?  The oak dish?  Any help would be appreciated.  Thanks.


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## CanaDawn (Jul 29, 2014)

That blackness is something I barely notice anymore, but it's not a problem with either the dish or the soap as far as I know, as I see it on all unfinished wood that is wet (not sure if the soap makes it worse or not).  My wooden scrub brushes do it, and I have seen it many times.

As far as I know, 100% OO soap takes a long time to cure (like months, not weeks), but I don't know if that is a factor in what you are seeing or not.


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## magician (Jul 29, 2014)

Thanks for the reply CanaDawn.  So this is something common with cold process olive oil soaps?  As I mentioned, this it the first batch I have made.  I'll put a bar or two away as well and let them cure for a month more or so and see if that makes a difference as well.


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## Susie (Jul 29, 2014)

100% Olive oil soap needs on the order of 4 MONTHS or more to cure properly.  Not that it is not safe, but it will melt quickly and not lather much.

Test your soap dish with just a water wet cloth for 15 minutes, and see if it turns black.


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## CanaDawn (Jul 29, 2014)

magician said:


> Thanks for the reply CanaDawn.  So this is something common with cold process olive oil soaps?  As I mentioned, this it the first batch I have made.  I'll put a bar or two away as well and let them cure for a month more or so and see if that makes a difference as well.



I have no idea if it's common with that particular kind of soap, only that I have seen unfinished wood used with water and cleansers turn black often.  Have you used a wooden dish with other bars and not had the blackness?


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## Shalisk (Jul 29, 2014)

I love woodworking and I happened to have a link explaining why woods change colors.
http://www.cabinetmakerfdm.com/564.html
There you are, hope this helps.


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## CanaDawn (Jul 29, 2014)

Shalisk said:


> I love woodworking and I happened to have a link explaining why woods change colors.
> http://www.cabinetmakerfdm.com/564.html
> There you are, hope this helps.




Great link

"If there is a trace of iron in the water, it can react with     the tannic acid on the wood to form iron tannate, which is     blue-black in color, although it appears grey if very small     amounts of iron are present. (This darkening also can occur     when using water-based finishes that have traces of iron,     intentional or accidental, in them.)"

That explains why I have seen it so much, because the natural water where I have lived has often been high in iron AND my family drinks a lot of tea (= tannic acid)


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## Susie (Jul 29, 2014)

And that was why I suggested the wet washcloth test.  I know that raw wood will turn odd colors with exposure with certain water.


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## magician (Jul 30, 2014)

Thanks all for the input. 

I tried the wet wash cloth experiment and it did not produce the blackening effect.  The oak dish looked just like a wet dish, so the water (we are on a well here) seems to not be the culprit.  The blackening only appears on the part of the wood dish that has come in contact with the soap.

Shalisk's link didn't seem to provide the answer to my specific problem either, but it made me think about what else could be reacting with the wood.  I searched to see what effect lye would have on raw wood and it turns out that a 10% lye solution in warm water is used to give wood an aged appearance.  http://www.woodworking.com/forum/archive/index.php?t-21789.html

So, making an assumption here (and we know how dangerous that can be   ) I am wondering if it may be that even though I can use the soap safely after 4 weeks the lye in the soap may still be affecting the wood.  Perhaps if I let the soap continue to cure for another 3 months (Susie pointed out that OO soap should take up to 4 months to cure properly) then the blackening affect might not occur.


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## CanaDawn (Jul 30, 2014)

Is it the lye or the pH?  Soap is always alkaline even after there is no free lye (ie, cured)

I honestly wouldn't expect the blackening after 15 min of being damp, but over more time.


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## neeners (Jul 30, 2014)

soap is also naturally alkaline.  could be the water plus the alkalinity of the soap that's turning your soap dish a different colour.  

 100% OO soap gets better the longer it cures (think of it like wine) - some say 4 months, other 6, others at least a year, and some say even 2 years is best cure for 100% OO soap.


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## Seawolfe (Jul 30, 2014)

If you made it right, there would be no lye, but the fatty acids have all turned into salts of fatty acids. Which may be what does it - our wooden soap rack turned dark as well where the soap touched it. It was originally darkened by commercial soaps, so its not a home made soap thing.


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## magician (Jul 30, 2014)

Seawolfe said:


> If you made it right, there would be no lye, but the fatty acids have all turned into salts of fatty acids. Which may be what does it - our wooden soap rack turned dark as well where the soap touched it. It was originally darkened by commercial soaps, so its not a home made soap thing.



I'm pretty sure I made it right.  It was a simple recipe, only 3 ingredients, and I used an electronic scale to make measurements correct.  I will put a bar of commercial soap on another one of the wood soap dishes and see if it gets the same reaction when wet.  Thanks.


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## DeeAnna (Jul 30, 2014)

"... Perhaps if I let the soap continue to cure for another 3 months (Susie pointed out that OO soap should take up to 4 months to cure properly) then the blackening affect might not occur...."

I seriously doubt you'll see much change by curing the soap longer. CanaDawn has the right of it -- it's the natural alkalinity of lye soap reacting with the tannins in oak. The natural alkalinity will always be present in the soap, even after a long cure.

Oak was darkened intentionally in the days of "Mission" and "Stickley" furniture by putting the wood pieces in a tent filled with ammonia fumes. The chemistry principle is the same whether working with NH4OH (ammonia) or NaOH (lye). 

My suggestion is to use a different soap dish. If you want a wood one, then pine, cedar, etc. will be better choices.


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## CanaDawn (Jul 30, 2014)

magician said:


> I'm pretty sure I made it right.  It was a simple recipe, only 3 ingredients, and I used an electronic scale to make measurements correct.  I will put a bar of commercial soap on another one of the wood soap dishes and see if it gets the same reaction when wet.  Thanks.



I'm not sure you will see the same reaction unless it's really soap, and not a detergent "body bar", and even if you made it perfectly, I'm willing to bet you will still see the reaction (as DeeAnna says, it's just something that will happen with lye soap and wood (and different wood will have different amounts of tannin, oak being quite high in it)

I'm sure your soap is fine.


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## magician (Jul 30, 2014)

Lots of great advice here.  Thank you all.

I have gone into full experimentation stage here trying to incorporate as much of the advice given as possible.

I put a bar of commercial soap on another of my oak soap dishes and it did discolour.  Not quite as bad as my home made soap, but discolour none the less.

I cut a piece of pine and chiseled it into a dish and put the home made soap in it and the discolouration does not appear to be happening.  I will check on it later to see if that changes though.

I have attached a picture of the blackening oak dish and the roughly carved pine dish side by side so you can see what I have been trying to describe.  

The oak dish blackened within 15 or 20 minutes of the soap being on it.


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## CanaDawn (Jul 30, 2014)

yup, totally normal reaction of oak to soap/alkali.  The commercial soap is either not lye soap or it is aged for a lot longer than your homemade soap but it will likely still eventually cause the same blackening.  You could possibly sand off the colour change if it is still shallow, and then finish with a waterproof urethane or something, but it would be easier to use a different type of dish.


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## magician (Jul 30, 2014)

Thanks CanaDawn.  I think the oak dishes will be replaced with pine dishes in the future.  I also will resist the temptation to use my soaps after only 4 weeks and see if I can't get them to cure for a few months more.


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## neeners (Jul 30, 2014)

if you make non-100% OO soaps, you can use at the 4 week mark.


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## samirish (Jul 30, 2014)

Ive never had my soap turn my wooden soap dishes black but I did have a wash cloth that was used to clean up raw soap batter turn a spot of my oak bannister black.

I assumed it was from the washcloth having active lye on it...


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## magician (Jul 30, 2014)

Well the soap has been sitting on the raw pine dish now for a few hours and not a hint of blackening.  I think I have found that the problem was the oak.  For what ever reason, the oak I was using for a soap dish reacted like it did, so I won't be using it any more for my soap.  The pine dish however, is working wonderfully, so I will make more of those.

Thanks to every one who chimed in with ideas and suggestions.  Seems the problem is solved.


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## DeeAnna (Jul 30, 2014)

Pine, cedar, cherry, birch, maple -- all should work well for soap dishes. You want a wood with a closed grain (oak and ash are open grain woods) so it will be as sanitary and easy to clean as possible. And low in tannins to minimize the very problem we've been talking about.


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