Hello All, I still have not made anything decent with my lathe - two round things from square stock and a rough looking goblet of sorts from a piece of cherry. I have signed up for a bowl turning class at my local Woodcraft for the end of this month so I am thinking along the right lines. My question to you all is about making a salad bowl from green wood. Assuming the wood of choice is compatible with food, is there any danger or problem in using the bowl immediately after it's turned? Can an oil finish be applied to a green bowl? I am not concerned about shape stability.
(I did a brief google search for green wood turning but after several citations I could not find one specific to my concern so that's why I'm asking) Thanks in advance to everyone for your advice. Marc
In general, wood can be used immediately after turning. Wood. Not the finish, just the wood.
Yes, you can use an oil finish on a green bowl. It will still change shape as it dries, of course. You may have to allow extra time for drying and curing.
Nearly all finishes MUST have time to fully cure (not just dry) before even considering food contact, and even then some finishes should be avoided. When fully cured (say, a month or two), most finishes are reasonably safe for food contact, but finishes that specifically say they're for food use (or are food) are definitely preferred (some say required).
For example, walnut (100% pure) oil or mineral oil are food safe because they *are* food (vegetable oil goes rancid with age). Same with pure beeswax or paraffin, they're edible so you can use them as finishes. You can buy "salad bowl finish" too.
And, of course, the instructions on the can take precedence over any of our nonsense you year on Usenet ;-)
Marc If you are making a salad bowl from green wood to use immediately AND do not mind if it distorts or cracks, use a wood that will not impart a taste, or at least not and objectionable taste, and oil it. Since you are making a salad bowl, a salad oil would be a good finish in this case. Do not use olive oil. It is a furit oil, not a nut oil, and it may go rancid. Just flood on a corn, canola, peanut or other nut oil, let it sit a while, and then wipe off any excess.
Botanically, corn is a fruit, as are all seeds and nuts. Corn oil is not a nut oil, though. Canola is a seed oil (from the rapeseed plant). Peanuts are beans (or peas), not nuts. But I think we all knew what you meant anyway ;-)
Another warning: don't use a nut oil if the people using it are allergic to nuts! Yes, you can argue that once it's fully cured they'll never eat the oil itself, but why take a chance?
Marc, yes you can apply oil to a green bowl, to a salad bowl I would put nothing but a food oil to it, if I wanted to eat out of that green wood bowl.
We use a couple of bowls for food and salad, and have used a couple of different oils in the last few years, never had any problem with oil getting rancid, the bowls get washed long before any oil will get rancid, the only problems that arise sometimes is the oil will get build up and becomes sticky if not used and washed frequently, a good soapy wash with warm water and rinse does take care of that.
DJ Delorie wrote in news: snipped-for-privacy@delorie.com:
Mineral oil is a food? Take a shot of mineral oil, you may find that food will try to escape from the other end. I've been wiping my salad bowls with olive oil for at least thirty years and they still are waiting to turn rancid. Might be the garlic. I believe Raffan uses olive oil on most of his kitchen type stuff. Regards, Hank
Or one could know that persons with nut allergies do _not_ have allergies to the oil (fat), rather to the protein in the nut. Which is why solvent-extracted oils are perfectly safe for them to eat and use, and even "organic" stuff _should_ be according to the AAAAI. The amount available to them on the surface of a bowl would be beyond vanishingly small.
Curing is the key point. If the oil cures fully, which some do, some don't, there's no problem with rancidity. If it cures partially, permitting bacterial or chemical reactions beyond full oxidation, can have a problem. Supply plenty of oxygen. Don't nest your bowls for storage, don't give bacteria and their chow a place to hide and operate by providing the lipid-friendly environment a non-curing oil, even a non-reactive type like petroleum oil can provide, and wipe with water/detergent before storage, vinegar before use.
Any oil, even curing, won't on wet wood. You'll extend the gummy period, and slow the wood drying process which ends the gummy period. Get as much unbound water as possible out of the bowl during and after turning. Secure and spin, run compressed air through it, what ever you have to do. After that, it would be nice to let a 3/8 thick bowl have a couple of days before oiling, though not absolutely necessary. Just know what's going to happen.
"Allergic to peanuts" doesn't necessarily mean "breaks out in annoying rash", it can mean "falls to the floor in anaphylactic shock and dies". If one can die as a result of a mistake then it's generally good policy to err on the side of caution.
I'm certainly not the most prolific nor the most knowledgable turner on this group, but I have been doing it for a little while.
Here's my procedure for green wood-
I turn it thin- about 3/16", sometimes a little thinner. After I get to about 3/8" of an inch in thickness, I start to jack up the speed. Right here, you've got some risk management to do- speeding up the lathe will help spin the water out of the wood, but that may cause it to crack- and if thin wood cracks when it's going at 2150 or 3000 rpm, it's going to be loud, and possibly dangerous. It's *usually* not a problem, but I've had a few pieces blow up like wooden bombs, so wear a face sheild and cut gingerly.
Then, I start sanding at high speed. At this point, it is less about sanding than it is about friction-heating the wood to drive out even more moisture. Be very careful when sanding the insides, though- it's easy to really twist a finger when reaching inside a fast moving piece.
Periodically, I shut off the lathe to take a look at the coloration of the wood- where it is dry, it will be noticably lighter, where wet, much darker. Once it is dry to my satistfaction, I slow the lathe down to about 500 rpm, and sand through the grits until I'm happy with the finish, speed it back up and burnish with a handful of chips and sawdust, and then finish it off with shellac or polyurethane.
About 90% of the time, this results in pieces that do not warp or crack. I have occasionally fully immersed smaller pieces in (tung) oil, soaked them for a while and then allowed them to cure, and it works fine- but there's a long cure time involved. Shellac and water-bourne poly will dry very quickly, allowing you to apply multiple coats in a short span of time, and they are generally fully cured and non-toxic within 24 hours (according to the directions). The advantage of that, especially if you are brushing on the finish, is that you can build a reasonable water barrier up right away, so that any remaining moisture in the piece is trapped. Some will undoubtedly argue with the value of that, as turning and finishing wet wood is more of an arcane branch of voodoo than a real science- but so far, it's been working out well for me.
It's also interesting to note that M&M candy is coated in thin layer of shellac- which is why it "melts in your mouth, not in your hand". If that isn't a food safe finish, I don't know what is! :)
Hey All, Thank you for the replies and suggestions. I am going to wait until I take that bowl turning class before I "try this at home" and make a few green bowls (and other stuff as well). I have a few green species available to me so I'll be looking up to see which ones are food compatible too. Thanks again for the advice.
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