bowl roughing question

[david brum]

OK, so I'm roughing out 7 walnut bowls that I cut into blanks a few weeks ago. The first 5 went fine, but I noticed that number 6 started to show cracks along the outside of the bowl as I was shaping it. They go maybe 25% of the way into the side of the roughed out bowl (1/4") . This wood is not exactly green, but it is wet. As an utter, rank beginner at making bowls, I'm wondering if there is a way to save this bowl. If the cracks don't get deeper, I can still turn them down. Is there a way to prevent the cracks from going deeper? CA glue? Epoxy? duct tape?

I am trying to post a photo of the bowl. I sprayed water on the cracks before I wrapped them in brown paper. As I was taking the photo, I noticed that the cracks had closed....

Thanks in advance!

[Jonathan Harvey]

I'm sure many will disagree but I say embellish the crack. Make it bigger and then fill it with something like stone or coffee grinds.

Like they say if life gives you lemons make lemon aid. :)

[Steve Schlumpf]

David - couple of things... it has been my experience that once a bowl starts to crack - it is going to crack. You can coat the bowl, soak it, glue it or whatever - but it will continue to crack. Jonathan has a great suggestion of filling the crack once the bowl has been finish turned. You can highlight the crack or blend the crack in to the rest of the bowl - it is your choice and just another part of learning to turn bowls.

Other thing you mentioned was that you roughed out the bowl and the cracks went about 25% into the side of the bowl (1/4"). Are you saying the walls of the roughed out bowl are 1/4" or that the cracks run about 1/4" deep into walls that are 1" thick? Reason I ask is that a general rule of thumb when roughing is to leave the walls 10% of the diameter of the bowl. This gives you enough wood to turn the bowl round again once it has dried.

Hope this helps....

[Bernie Weishapl]

David I always, like Steve said leave my bowls about 1" thick when roughing. If they start to crack like yours is I soak with thin CA well past the cracks. This seems to stop most of them. After it dries I then DNA soak.

[Harvey Ghesser]

Bernie et all.... I need clarification please. I'm new to woodturning as well. When you say to soak in CA, are you saying to just add thin CA (cyanoacrylate) to the areas that are cracked? I guess I'm confused by the word "soak".

Thank you for any advise!

Harv

[Richard Madison]

David,
If I understand correctly, you say that on one bowl you sprayed water on the outside, the cracks closed, and you wrapped the bowl to allow it to dry. Suggest that you not add anything to the cracks in that one until after it is completely dry. You may find that when the piece is completely dry there are no cracks. If still cracked, that would be the time to CA, fill, or whatever the treatment of choice.

When roughing wet or damp wood it is sometimes helpful to keep the outside wet or moist while you are turning the inside. Oak, in particular, will begin to crack as you stand there looking at it.

[Reed Gray]

For me, cracks never go away, and almost always get bigger. I have noticed that trees/logs that have been down for a year or two will crack sooner than fresh green wood. As far as the cracks appearing while you are turning, I don't really know how they appear. If you have a halide light close to the wood, it can generate enough heat to cause those shallow checks, kind of like from getting too much heat while sanding. Most of the time, I will put cracked bowls in my factory reject box which I usually dispose of at one particular show I go to. From a production point of view, it isn't worth the time and effort to fill the cracks, and cracked bowls are much slower to go, even if I lower the price. I only do crack repair on special pieces.
robo hippy

[david brum]

Wow, thanks for the response guys. To clarify, the bowl is around 11" in diameter and I left it about one inch thick. The cracks go about 25% if the way into the wood.

Thanks for all the advice. I'll monitor the bowl over the next week or so. If the cracks don't open more, great. I'll turn it down to a 10 1/4" diameter bowl. If they do, I will definitely try embelishing the crack. Even though I only have an hour and a few bucks into the bowl, it still seems precious.

After I get the other two bowls roughed, I'm going to try DNA soaking. After that, I have a million questions about wall thickness, finishing, etc.

Thanks again

[Tom Storey]

You are probably keeping your gouges sharp, arn't you? I've heard that dull tools will produce enough heat when being forced to cut that the wood will sometimes crackhttp://www.sawmillcreek.org/images/icons/icon12.gif When in doubt, sharpenhttp://www.sawmillcreek.org/images/icons/icon10.gif

Tom

[david brum]

You are probably keeping your gouges sharp, arn't you? I've heard that dull tools will produce enough heat when being forced to cut that the wood will sometimes crackhttp://www.sawmillcreek.org/images/icons/icon12.gif When in doubt, sharpen.

Good question Tom. I'm sharpening as soon as the shavings start getting dusty, probably 3 times for the outside and 3 times for the inside. Nothing feels hot, but what do I know?

[David Peebles]

Hi David,

I see from the pic you posted that there is a lot of sapwood vs heartwood in the bowl blank. In my experience this can cause a lot of tension in the wood. They seem to dry/cure at a totally different rate.

I think you can wait and see what happens over the drying period. But I find these usually end up in the BTU recycling bin in my shop... aka Wood stove. :)

But it is all good, experience is always the best teacher. And after all, this stuff does grow on trees.

Good luck,

Dave

[Dan Forman]

I'm just getting started with bowls too, and all 3 of my walnut bowls so far have cracked, the last one, like yours, before the rough turn was completed. Cracks were all in a similar area, near the rim. All had been cut last year and sat outside I untreated until I got them a couple of weeks ago. I don't know if that was a factor or not, as I have nothing to compare to. Like yours, I would describe the wood as damp (enough to mold), but not wet.

Dan

[Jeff Nicol]

Well here is what I have seen over the years with walnut. If the tree was down for over a year the bark will start to release and fall off. This let air directly to the out sapwood and it will start to dry faster especially the part of the log that will get the most sunlight as it lays in the yard. The wood will start to crack down radial lines and when you turn it they will appear. The part of the log that was on the ground may have some rot but will not do this as the moisture is greater there. But I would do just as Bernie said. Drip some thin/medium CA in the cracks and let it soak in and then do whatever you do to complete the drying: DNA soak, Anchor seal, paper bag and shavings or wahtever. The CA will stop the crack from continuing or slow it greatly so when you finish turn it the crack will be a thin line and easily stabilized with CA again in the finishing stage. Good luck and don't give up!

Jeff

[david brum]

I see from the pic you posted that there is a lot of sapwood vs heartwood in the bowl blank.

David,
I got the wood from one of my buddies, who is a sawyer. He said that lots of sapwood is very common here in the Pac NW (for walnut). The sapwood definitely behaves differently while turning. It seems like the heartwood holds more water and dulls the lathe tools faster. I can see how it would dry at a different rate.



Like yours, I would describe the wood as damp (enough to mold), but not wet.

Exactly Dan, my blanks got a bloom of mold after a few days. They also made an impressive mess of the inside of my bandsaw.



But I would do just as Bernie said. Drip some thin/medium CA in the cracks and let it soak in and then do whatever you do to complete the drying: DNA soak, Anchor seal, paper bag and shavings or wahtever. The CA will stop the crack from continuing or slow it greatly so when you finish turn it the crack will be a thin line and easily stabilized with CA again in the finishing stage.

OK Jeff. I'll pick up some CA glue and give it a try.

Thanks again, all.

[Kim Ford]

Dave;

Walnut can be fun when it is semi-green. A construction company my daughter works for in Kentucky gave me several hardwood logs from a clearing they were doing which included a walnut log that hand been felled over a year earlier. I roughed out about ten blanks 12-14" in diameter with about 1" walls, and thought I hit the mother load.
I baged them with some shavings from the log and thought everything would be well. Fortunately, my daughter called and asked if I could turn one green so she could give it to her supervisor as a thank you. This was a day or two after I had bagged them, so I picked one of the bags and opened it up to turn a green bowl, and the cracks you described were everywhere. I opened all the bags and all were the same.
I keep several large trash cans in my shop that I put the shavings in and they were still there from the roughing out exercise and pretty much full of walnut shavings. I immediately buried the blanks down in the shavings in various cans, and old trick that works well, and started experimenting.
The best results were the blanks that I put back on the lathe and turned out the cracks, (about 1/8" on each side), and then put back in the shavings for a couple of days, and then did it again and again. Yes they did warp a little and when the blank reached the point that I knew I did not have enough wall thickness to go another cycle, I finished them off, sanded (don't let heat build up or you get more cracks), and polished. I then took them to the microwave and did the Raffan trick with the microwave. The finished product was really quite nice for a green turned bowl with wall thickness of about 5/16".
I've would now probably try the anchor seal coating process on the green blanks because it has been successful on other green woods but at the time I wasn't doing it.
Good Luck.

[david brum]

Thanks Kim. I thought about burying the bowls in shavings, but the shavings are so wet, and it's so damp here in the PacNW that I'm pretty sure everything would mold.

If all goes well, I should be able to turn down the cracks. Here's hoping that the other bowls behave themselves.

[Reed Gray]

A 18 inch diameter Walnut tree here in the Northwest can be over half sap wood. A 30 plus inch diameter tree will have maybe 2 inches on the outside. Size matters. I have found Walnut to be fairly easy to dry, with little movement and little cracking.

robo hippy

[david brum]

Thanks for the encouragement Reed. This tree was probably 20" diameter. I was pretty surprised to see so much sap wood. The contrast is kind of cool though. This log was seriously heavy. I sawed it into 60-80 lb chunks in order to get it home. My back was talking to me the next day.

[Kim Ford]

[QUOTE=david brum;1161861] I thought about burying the bowls in shavings, but the shavings are so wet, and it's so damp here in the PacNW that I'm pretty sure everything would mold.
QUOTE]

Dave;

I did get a little bit of mold as well, but it was only on the surface. I didn't leave them in shavings for more than a couple of days each time.

Another trick that a friend of mine in Hawaii uses is she will turn a wet blank and then put it in the freezer for a couple of days to hold it until she is ready to turn it again. It doesn't dry it out it simply "suspends" it and keeps it from cracking. With the Wisconsin winters we get I will do the same thing except I just put them in my unheated garage. It will buy time until I can get back to then next step.

Kim

[david brum]

Hmm, that's an interesting idea about the freezer. I'll have to think of an appealing way to present that to my wife.

Thank goodness it never gets cold enough here in winter. Everything does mold, mildew or rot though.

I'll try the shavings on the next bowl and see what happens. Thanks for the advice!

[Reed Gray]

The sap wood will oxidise or get brown or grey as it ages (like the sap wood on cherry goes from white to orange in a few minutes). In fancy terms, that is getting a 'patina'. The shavings can leave spots on the wood that are visible. If you are returning the bowl later, most of this will turn away. If you turn to final thickness while green, the spots will not sand out, and the oxidised sap wood will sand out unevenly. If you have it in dry shavings, this is not as much of a problem. Personally, I like to turn to final thickness and let it warp. It is easier to dry, and I get less cracking. Sanding is a bit of a problem as you need lathe speeds of 10 rpm or so, because any faster than that, and you can't keep your hand or sander on the wood.

I do store my log sections burried in damp shavings from the chain saw and from turnings, with tarps on bottom, top and sides. This creats a nice humid environment for the wood to sit in. Sinking logs in the mill pond is another method.

robo hippy

[david brum]

Thanks for the insight Reed. I like the idea of storing logs chunks in shavings. It seems like efficient use of materials.

I did turn finish turn a small, practice bowl which I gave to my daughter a few weeks ago. She filled it with "interesting rocks" and so far, no sign of cracking. I'd guess the wall thickness was just over 1/4".

Turning with walnut is interesting. When I committed to using the wood, I assumed it would pretty much be uniformly heartwood color. So much to learn about different woods. I'm anxious to try some bowls from Big Leaf Maple next. It grows everywhere around my area.

[Reed Gray]

A few other things about Black Walnut. After drying, the wood will have a strong walnut scent. Some people love it, and it drives some people crazy. I make sure to tell people about that before they buy one. I don't think I would like to eat ice cream out of a walnut bowl, but main course meals or salads (not fruit/sweet ones) would be fine. Also, lemon juice can help cut the walnut stains on your hands.

BLM is a great wood to turn. Not really hard, it does tend to get a bit stringy as in end grain tearout, but very light cuts with a freshly sharpened tool can eliminate most of that. Leave it for a year and it will color nicely most of the time, and it looses water very fast. It will lose over half its weight in water in a few summer months.

Dave, I don't know where in the Northwest you are, but if you are ever coming through Eugene, stop by and see me.

robo hippy

[david brum]

Yeah Reed, I was surprised to see black stains on my hands. My hands are usually dirty anyway (occupational hazard) but it surpised me that the stains stayed on for a few days.

Thanks for the info about the smell. My shop has had an unusual fragrance since I brought the wood in.

I'd love to visit if/ when I get down that way. I'm up on the Olympic Penninsula, so the same goes if you're up here.

BTW, what kind of finish do you recommend on walnut? I had thought of Tung Oil to give a non-glossy finish, but I'm open for suggestions.

[Reed Gray]

Dave,
I will be in Seattle the second weekend of November (12 through 15th) for the Best of the Northwest show at the Seattle Center near the Space Needle. I am going to try to get to the club meeting in Kent which is on that Thursday. Not much time for travel outside of that.

For food bowls, I like Mike Mahoney's Walnut oil. It takes a week or so to dry out enough so that it won't leave rings on a table cloth. Putting it over a 70 watt light bulb for a few days will help it. The tung oil will work as well, but I wouldn't use the bowl till you can't smell the finish or actually the solvents any more. Surface finishes (sprayed laquer, water based finishes) will eventuallly chip and peel off, and then the bowl looks horrible, but will be fine for decorative pieces.

robo hippy

[david brum]

That would be a great excuse to get over to the city in November Reed. I'll look you up when I get over there?

Thanks for the advice about the oil. I do intend these to be used. I'm making them for a Waldorf school benefit auction in October. Since the bowls are from locally harvested trees ( and if I don't screw them up) they should be popular. If you give people enough wine, they can really bid a lot for things like this ( I hope).