I'm turning cherry bowls from green wood. Some of them I've been wet sanding, some of them I've been drying the surface with a heat gun and sanding conventionally. When done, I bring them into the kitchen sink and give them a thorough wash, and wipe dry with a clean cloth. Sometimes within half an hour, sometimes longer, I'll find little blue dots appearing. It looks like very fine sprayed ink, and is unsightly...had thought of the water, but thought the wiping would've taken care of that. Any help is greatly appreciated, thanks.
>Perhaps you have a high iron content in your water....try your next bowl with some bottled water. Also, just curious, why are you washing the bowls at all?
Another thought, take one bowl for a test piece and now treat the blue spots with some lemon juice which sometimes removes stains caused by metal.
>Tony, the one question I have is Why? You are the only one I have heard of that washes wood after the final sanding. Just wondering what added value there is in that step. To address your question, though, in my own experience with wet Cherry, those dots are from mineral content, such as ferric particles from the water or steel wool debris (which is usually the culprit in my studio. Can't seem to keep that stuff away.)
I, too, wet sand the piece, with water for a lubricant, and have found the black dots a few times. Maybe distilled water would eliminate the spots if that's the only ferric contamination source.
For those of you wondering why I'm not wetsanding with thinned finish, the oil based finish quickly permeates the end grain and spoils the piece with blotching. It goes through the endgrain like a sieve, or coffee filter, and looks like crap. I've begun to spray a sealing coat of shellac first, then add the oil based product if that's what I want. Mostly I've been just finishing with the shellac as soon as the sanded surface is dry enough, then rubbing it out and applying a good wax. I've found that "popping" of the grain with oil on Cherry isn't as appealing as it is in, say, Tiger Maple, for instance, and the elimination of the blotchy effect is well worth the effort for me. Keep in mind I turn the pieces real thin, to avoid distortion from drying. With the protocol I have evolved, I can turn a closd form in the 16-20" range with a 1/8" wall that distorts very little as it dries, leaving the finished product looking like it was roughed, dried and returned. I keep saying I'm going to get a software package to resize my pics for posting, but I end up doing something else. If I had, I could take a shot of the latest one so you could see what I'm talking about.
>I guess that's the biggest benefit of these discussions. I use lemon juice to clean my hands a lot, but didn't think about trying it on the spots. I will, next time. Good idea, and thanks Jim!
Re: problems with green cherry bowls "speckling" *LINK*
Mike Schwing from Ocean City, MD
>Doug,
For many years I have been using something called "Polyview" for image editing. It is FREE, and very versatile and powerful (especially since its free). Its not Photoshop, but it will resize, crop, edit, sharpen, etc... all sorts of images. I frequently use it to prepare images for showing here on WC and elsewhere. Until you're ready to buy a package, consider giving this free one a shot... www.polybytes.com
I'm sure that I am not the only one here that would like to see your work.
>(opinion)........find out if the speckles/blue dots are internal to the wood by putting a bowl or specimen cherry piece in the microwave. It will cook out more dots if its internal to the wood...if so the wood is just wet and the specs will disappear with drying..if not its something external..sandpaper grit, iron oxidation or whatever.....gtools.....
The problem is probably tiny bits of iron in the wood. I would bet it's coming off your tools, not out of your water (though that's possible, too). When you sharpen your tools, you create a fine and fragile edge and associated burr, which breaks of in tiny little bits. These can definitely get into the wood, and with species like Cherry and Oak, they will cause blue/black spots. Lemon or lime juice will help, but you might consider "washing" your tools (say, honong, stropping, or even wiping with a towel), not the wood.
>Mike....This is a form (LOUSY pic) that Doug and I turned one day at his home in CA before we both decided to "get outta Dodge". (Hope you don't mind, Doug) Actually, he was teaching me how to turn a green hollow form, and ended up doing 80% of the turning! It's Maple with Ebony top/finial and measures 7 1-8"H x 6" at its widest, and less than 1/8" thin. While still in CA, the form moved various times, but since we've been here in AZ, it's back to dead-on round...at least by MY calipers! Come on Doug....get yourself some software so we can see more of your great work! ;-)
>Hey guys. To answer a question, I washed the pieces in question to try and get rid of all the sanding dust, to raise the grain for final dry sanding, and also to try to elimnate any little pieces of iron/steel that might be there from the sandpaper or tools. I was thinking about the Del Stubbs turning video when I did it; he recommended hot soapy washing, I believe.
I didn't know that cherry would react to metal as oak would, that's good to know.
Thank to all who have responded (and will!) here and in personal contact, I appreciate it very much.
The biggest question still seems to be whether it's fast growing mildew or metal reaction. I guess perhaps washing in lemon juice might help that question, huh?
>Well, if it isn't the ornery ol' f*&t! Great to see you here, my friend!
I didn't remember the ebony on that piece. Man, it's been a while since we did that one, hasn't it. We had a lot of fun that day. Not sure we got the best curve on it, either. Looks like we interrupted the curve somewhat, but it was a pretty piece of wood. Surprised you didn't sell it. How's the scrolling going?
Yeah, folks, we got out of SoCal, just like Jim Delaney is going to do soon. Trouble is, Cort only went as far as the desert in AZ, I guess I needed to get farther away, all the way to SW PA.
I downloaded the software Mike, so if I can figure out the process, I'll put up a few pics soon. Now I need to get a better camera. Never ends, does it? Actually, a guy in our club is a pro at the university here, and has offered to do some good pics for me. Looking forward to that! Like an actor getting free head shots, you know?
>I love working with cherry but have found many different species. Just for grins, there is a great chapter in Thomas Moser, Artistry in Wood about working with cherry. That's pretty much their primary wood for their furniture. This is a great book if you have not seen it.
It is most likely particles from your tools as Brad mentioned. I turn quite a bit of green black cherry. The solution I have found is to keep a bottle of lemon juice at hand - cheap at the grocery store and lasts a while. After final turning, and sometimes after final sanding I dampen a sponge or paper towels with the juice and cover the entire surface of the piece. Haven't seen the blue spots since.
