Sunday, July 08, 2012

Oh no! Black stains on wood!

There has been a little debate lately among my woodworking buddies about scrapers. John E was having some trouble getting a burr on his scraper, and enlisted the help of several people here in town, still without any luck. It started me thinking about my scraper situation. I don't use them all that often, but sometimes, a scraper is the only tool that will do the trick.

I ran into a neighbor on the Fourth of July who asked if I would apply a little TLC to his 50 year old cutting board. His dad had made it, so it had a lot of sentimental value. Working on projects like that make me nervous. What if they blow up in the planer, and then you've destroyed someone's favorite possession?

As it turns out, the board was too wide to fit into the planer anyway. It was badly warped and didn't sit flat on a countertop.

Oh great - more stress!

I cut it apart, and ran the fresh edges over the jointer. The piece went back together flat! I used a few Dominos in it, to align everything while I glued it back together. Sometimes, bar clamps leave an ugly black stain on your wood - it's the reaction of metal on wood from the moisture from the glue. The tannins in the wood react quite fiercely with metal - it is really evident on oak, which has a high concentration of tannic acid in it.

Black stains on oak desks are really common - ever leave a sweaty water glass on your oak top over night? You'll get a hideous black water ring, under the right conditions. This blog post is great for giving you an idea about what they look like, and how to eliminate them. This one is good, too.

I've had good luck using Oxalic acid for getting rid of those nasty black stains. But in this case, I pulled out my trusty Kunz scraper. I like this tool so much better than a simple card scraper, the burr on the edge stays rolled much longer. I've had this tool forever, and pulling it out is like calling an old friend on the phone. (If that makes any sense!)

The good news is - the the cutting board went together quite nicely, the glue and stains were cleaned up quickly, and I applied a few coats of oil to it. It lost a little of its golden patina from being fifty years old, but that's OK.

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