Sweat + Steele + Tannin = Purple Blotches - Part 2

[Eric Jacobson]

This is crazy. I wanted to post some pictures and see if any of you have refined a solution since this thread (http://www.sawmillcreek.org/showthread.php?147944-Sweat-Steele-Tannin-Purple-Blotches).

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This is Oak, not sure what kind. The first picture shows the stains from the face plate. No big deal because you turn it out. After I left the bowl sitting on a metal table saw top, the next day it was covered with purple dots. In fact, just 12 hours later, the purple dots have spread from the base to the outside and inside walls of the bowl. The 3rd picture shows the little purple dots. It's getting worse as I type this...just sitting in the shop. It's like the bowl is allergic to metal and breaking out in hives.

This bowl was going to be a Christmas gift but I messed up the base anyway. I'm about to turn a replacement from the same oak but I'm wondering if I even want to bother. Someone said Walnut oil or lemon juice would fix the problem but for how long? If I give this bowl as a gift and someone sets it on metal, I'm worried it will start all over again.

And I have a 2.5' diameter log of this oak sitting in my driveway waiting for me.

What would you do?

[Dennis Ford]

I think that is red oak.
If the lemon juice gets the color out, it should be OK once the wood is dry. The staining problem happens with wet oak.

[Thom Sturgill]

Someone else can correct me if I'm wrong, but might it not help if you use stainless screws next time? Or even brass? As just mentioned in another thread steel wool dissolved in vinegar is used to stain oak or other high tannin woods black.

[Richard Coers]

Ever seen an oak log with metal in it? The blue stain can run for several feet up and down from the metal. I think it will take a 2 part wood bleach to lighten the stain, but even that will probably not remove it. Lemon juice can remove a stain from your hands, but I don't think it will be enough for the bowl. I bet that table saw top didn't fare very well either! Stainless steel screws with a layer of saran wrap between the faceplate and the oak, or, buy a plated, 4 jaw chuck. Maybe even a couple coats of lacquer on the faceplate a few days before turning will provide a barrier. SS screws will be a must.

[Prashun Patel]

If it were me, I would go with it this time: Soak some steel wool in vinegar overnight. Then wash the bowl in the resulting solution and watch it turn jet black. The prominent grain of oak along with its open grain structure makes for a wonderful effect when dyed black like this. It'll be very striking.

[Faust M. Ruggiero]

Soak some shredded steel wool in white vinegar for a few days then coat the bowl. The whole thing will turn an amazingly rich brown and hide the marks. Tannin reacts with metal badly unless you marry the two intentionally.
faust

[Steve Mawson]

I like Faust's idea or you could just use some wood stain. I had the same problem with some white oak. It as amazing at how fast the wood reacted with metal. I have to believe you still have quite a bit of moisture in this wood but don't know for sure. The piece that I had did darken up a lot by itself after I put it in some home brew danish oil. All this said Christmas is not very far away and that might make the project a little tougher. Always ask for help from Santa's elves.