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Discussion Starter · #1 ·
I am new to woodturning. So far, a self taught novice with a 30% success ratio. The only two decent bowls I have produced recently came up with an odd problem related to the finish. When exposed to tap water (my wife insists on washing them), black specks form over most of the bowl. They form in the pours of the wood and are very difficult to sand out.

The wood in these bowls are different. One is oak and the other is a layered block made of walnut, blood wood and maple (I think). The only common features are the water and the finish. Both bowls were finished with three coats of walnut oil. The water is from our well and goes through a water softener.

I have researched the Internet looking for similar problems with various wood types, with walnut oil and related to water softeners. So far, I have found nothing. Anyone have any ideas????
 

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Sounds like mold to me.

To confirm try wiping over with a paper towel wet with a bleach solution, or spray on Chlorox if you have this around.

Open grained wood like oak has many places where moisture can reside, and mold spores are always in the air waiting for a chance to grow.

The walnut, bloodwood and maple are much closer grain.

The first cutting board I made used soft maple. This was mounted on a counter. Bad idea. Liquids would get underneath and I did get black spots like you mentioned. The board was not well constructed for this duty and the ends split. I did recycle the wood to make coat hangers, etc. and had to plane it to get back to a clean surface.
 

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Did you use any steel wool.

Tannins in oak do not mix with iron particles. Even sharpening a not stainless steel in the area can leave specks of iron to turn black/ purple.?.
RHB
 

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If it were just on the oak, iron, maybe even from the well water, would be the likely culprit. I don't believe either maple or walnut would show the effect with iron, but not sure about the bloodwood.

The walnut oil isn't much of a barrier.
 

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Discussion Starter · #5 ·
Dave, Bob and Ed,
Thanks for the quick replies! All have some promise for a solution. I will try the bleach wipe when I get home tonight, just to eliminate the possibility. However, on re-inspection, I believe that lighter wood in the layered bowl is oak as well. So I am guessing that iron may be the culprit. I am having my water tested today. The results will tell me a lot. Also, I used steel wool on both bowls. That could be the biggest issue, right?
 

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Dave, Bob and Ed,
Thanks for the quick replies! All have some promise for a solution. I will try the bleach wipe when I get home tonight, just to eliminate the possibility. However, on re-inspection, I believe that lighter wood in the layered bowl is oak as well. So I am guessing that iron may be the culprit. I am having my water tested today. The results will tell me a lot. Also, I used steel wool on both bowls. That could be the biggest issue, right?
Yes, more information. Steel wool will leave minute particles in the pores. The tannins in oak will turn steel black, as mentioned earlier. All it takes is oak, steel and a little moisture.

Some months ago there was a post about an oak surface having black rings. This had been caused by steel cooking vessels being left in contact with wet/damp oak surface.
 

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My first thought, too, was that steel wool may be at fault. Some people swear by using steel wool on their projects. But it's really not the best idea for this very reason.
 

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[ So I am guessing that iron may be the culprit. I am having my water tested today. The results will tell me a lot. Also, I used steel wool on both bowls. That could be the biggest issue, right?[/QUOTE]

If you used Steel wool hat IS the likely culprit. Well water would not leave spots. It is important to keep iron filings away from wood especially oak. If you use caarbon steel tools, your sharpening system needs to be well away from you woodworking area.
For fun and interest, put a bit of steel wool in vinegar overnight and wipe the liquid on some oak the next am. This can be used to darken, ebonize oak. The colour is a bit blueinsh but if you then add some walnut stain or Indian ink you will have a beautiful black stain.
Bob
 

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Discussion Starter · #11 ·
Problem Solved

Thanks everyone for the replies and advice. It was the steel wool! I have sanded the spots out, refinished the bowl and subjected it to water. No issue!
Live and learn.
 
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