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Turned aged cedar cup

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Forum topic by LKaan posted 12-18-2017 10:22 AM 497 views 0 times favorited 15 replies Add to Favorites Watch
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LKaan

11 posts in 123 days


12-18-2017 10:22 AM

Hello everyone,

I’m LKaan.

I’m very new to wood turning and woodworking in general. I have recently turned an aged cedar log, pith to pith and it went perfect. I let the finished cup sit over night and it showed no signs of cracks. The next day I burned a name into it and shortly after I coated it with polyurethane finish. As soon as I started coating the bottom of the cup it cracked and popped and showed only one crack so I let it sit and dry. Then upon the 2nd coat it split from the bottom and up one side. I don’t have a clue as to why or how to prevent it. Any pro advise would be much appreciated. Thank you.

-- Learning the wood whisper.


15 replies so far

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LeeMills

522 posts in 1265 days


#1 posted 12-18-2017 05:02 PM

Not a pro but I have lots of problems with cedar. It is very easy to crack in my experience.
You turned pith to pith so I assume the pith is till in the bottom of the cup? The pith should always be removed; I have turned a few that way but I cut out the pith and inserted a new piece in the base.
If it was in your shop, and your shop is not conditioned, the moisture equilibrium may be much higher than in your home if you took it inside to finish. In the winter my shop/home varies by up to about 7% which is enough to cause cracking sometimes.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

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LKaan

11 posts in 123 days


#2 posted 12-18-2017 06:16 PM

Awesome, thank you for the insight. I turned it in my shop and brought it into my house as soon as I was done sanding for burning and finishing. I sanded just after turning. Our moisture content is very minimal here in NM, not sure of percentage but the temperature was quite low during turning and the house is considerably warmer than my shop. I did let the piece sit for about 15 hrs in room temp and figured it would be stable because there was no cracks or pops. I thought it could be moisture in the poly but I’m really clueless. I’ve very little luck with the cedar but managed a few pieces that didn’t crack, but I also didn’t apply any finish/poly, Shellac ect. I’m considering turning another test piece then let it sit in ambient temperature to see if it cracks then I’ll apply the poly if the piece stays stable overnight. If it cracks after the poly, should I assume it’s bad poly or just ultra dry wood that should not have poly applied to it?
I will also remember the pith should be removed.

-- Learning the wood whisper.

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LeeMills

522 posts in 1265 days


#3 posted 12-18-2017 07:31 PM

I have never heard of a finish causing cracking but it may happen. I would assume if it is water based poly it could do the opposite and cause the wood to swell instead of shrinking but that shouldn’t cause it to crack.
Heat, especially with cedar can also cause it to crack My Gdaugter had some jump rope handles crack when she sanded them too aggressively and had heat buildup.
It appears from you pic that the crack ran through the middle of the name you burned so the burning may have dried that area much more than the surrounding area. Just a wag.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

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LKaan

11 posts in 123 days


#4 posted 12-18-2017 07:50 PM

I did burn it and finish it rather rapidly so i suppose the piece could have had residual heat and the poly was @ room temp so the difference in temp may have been cause. I’m unsure if the poly was water based but I wouldn’t think so. The crack is actually just at about the end of the name and is only about 2 hairs width now as I panicked and spread the crack and applied CA glue then put a black rubber foam liner in the Chuck, clamped it closed and squeezed the mouth by hand until it dried. I sanded the CA glue to level and touched up the poly finish. When I separated the chuck it came out fine but the foam incidentally adhered to the wood. Unfortunately some of the foam also made it into the bottom of the crack and couldn’t be removed. Luckily it’s a beer can holder and should serve it’s purpose well.

-- Learning the wood whisper.

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OSU55

1630 posts in 1953 days


#5 posted 12-18-2017 09:07 PM

More than likely the log was wet inside and the cup cracked as the wood dried. I turn a lot of bowls & platters vs cups but the principals are the same. Rough turn the piece leaving 10% or so thickness, put in kraft paper (brown grocery bag) with some chips, tape closed, let sit a month or so (depends on thickness). Paper bag is a moisture barrier to limit how fast the wood dries which limits cracking. Applying finish wasnt the cause. Cedar is not a wood I turn – brittle, not great structurally. Hardwoods are better for turning.

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LKaan

11 posts in 123 days


#6 posted 12-18-2017 09:23 PM

I guess it could have been wet still, though it did sit outside for about 1 year. I wasn’t aware of putting it in a paper bag if it was seasoned already. I do indeed put all my green pinion turnings in a paper bag. On another note, I noticed cutting the wood parallel to the grain and leaving the pith out for say a small bowl; when beginning the roughing, the ends of the wood splinter very badly. I also do not have a band saw for rounding and use a table saw to get as close as my eyes will allow and I’m guessing that has a good bit to do with it. Thank you for all the input. I’m an open book and am absorbing as much as possible. Much appreciation. I’ve found that I’m hooked on turning and I really enjoy making a huge mess in my shop as well as amazing colored mulch. :-) Any and all advise is absolutely welcome.
As far as hardwood goes, there is none naturally occurring in my area. We do get some scrub oak but it’s really prone to horrible warpage.

-- Learning the wood whisper.

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HorizontalMike

7749 posts in 2877 days


#7 posted 12-18-2017 09:34 PM



More than likely the log was wet inside and the cup cracked as the wood dried. I turn a lot of bowls & platters vs cups but the principals are the same. Rough turn the piece leaving 10% or so thickness, put in kraft paper (brown grocery bag) with some chips, tape closed, let sit a month or so (depends on thickness). Paper bag is a moisture barrier to limit how fast the wood dries which limits cracking. Applying finish wasnt the cause. Cedar is not a wood I turn – brittle, not great structurally. Hardwoods are better for turning.
- OSU55

Myself, very limited bowl/cup turning, though I have experienced all of the above, feel that the above is accurate enough to pay attention to. Just my 2-cents worth…

Most of my turning has been limited to hand plane knobs and spindle legs and such…

-- HorizontalMike -- "Woodpeckers understand..."

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LKaan

11 posts in 123 days


#8 posted 12-18-2017 09:59 PM

I’m definitely paying attention and welcome more at any time as I’m a beginner. I have been keeping notes on my selection of wood and how I cut it in prep for the lathe. I have to be very picky on the wood I use because I lack a band saw to properly pre shape the wood. I don’t have access to hardwoods or I would definitely use that instead.
I can’t afford to order the hardwood and end up ruining it, as I still lack much skill and live 150 miles from any lumber store lol. So im hoping to get my skill up to par before I use what we would call an exotic wood to try my hand at it.

-- Learning the wood whisper.

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OSU55

1630 posts in 1953 days


#9 posted 12-19-2017 12:26 AM

I found I had an arborist? ( tree trimmer/cutter) about a mile from me so I get all the free fresh cut logs I can handle. If there is a town nearby, bad storms take out trees and some not all will let you take them. Seal the ends of the logs and leave them whole until you are ready to cut abd turn blanks. I keep the wet blanks in a plastic trash bag so they dont dry out. They can get moldy but hasnt been an issue. I try to turn them within a few weeks. A bandsaw isnt required, but a chainsaw pretty much is. I mark a circle and cut the corners with the chain saw. Sometimes use a sawzall to balance out a blank. If you love to turn a chainsaw is in your future and a way to haul short logs.

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LKaan

11 posts in 123 days


#10 posted 12-19-2017 12:47 AM

Oh man, that’s an awesome idea. Thank you very much. I’ll get in contact with the highway Dept, they may have the arborist or know of one. I’m curious how you seal the ends of the logs? I’m very familiar with a chainsaw as I live in the mountains and am an outdoorsman. I’m awash with small cedar, huge juniper, and very small to extremely large pinion trees. I’m highly allergic to juniper and mildly to cedar so I use a respirator and have a gas mask on order. Hopefully I’ll be able to work a wider variety of wood soon.

-- Learning the wood whisper.

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OSU55

1630 posts in 1953 days


#11 posted 12-19-2017 01:24 PM

I use anchorseal but there are other ways – melted wax, paint. Search for cutting bowl blanks and that will get you started and from there you will learn about cutting blanks for whatever you want to turn. Ask the hay dept about other types of trees, maybe in a town near you.

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Tennessee

2860 posts in 2478 days


#12 posted 12-19-2017 01:37 PM

How old was your piece – in other words, how long off the tree?

I waited 7 years before turning this bowl out of an old growth cedar tree that was taken down on my property. It is about 8-9 inches in diameter finished, and stands about 12” tall. Here is is shown still on the lathe, with its last coat of poly on it, four coats total, sprayed on.

It was turned sometime this summer, (can’t remember). Was a real monster, turning it completely dry, but I got there.
It is in a gallery for sale, (unless it sold for Christmas and I just don’t know about it yet…Hope, Hope)

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

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LKaan

11 posts in 123 days


#13 posted 12-19-2017 02:59 PM

Great info, thank you all very much. I did do a search and found that I have access to lots of aspen/quake, and got great returns when I searched for “cutting bowl blanks”. I’m so stoked to go cut some down timber into workable pieces. I would say the cedar I used has been down for nearly 1 year but I feel that its closer to 1 1/2 yrs. Most likely still damp.
What I don’t get is, I turned the piece and let it sit for about 15 hrs and it didn’t make a sound, no poping or cracking. Then as soon as I touched it with the poly brush, it instantly started popping then moments later it showed signs of a small fissure in the bottom about the pith. So I’m now thinking that I should have used poly spray rather than a brush and liquid. I really don’t know for sure though. Again I really appreciate all the information you fellas have shared.
I would still be at a loss for info if it wasn’t for this site.

That is a beautiful piece you have there. Amazing color, and is that a natural edge? Nice skills, very good looking work Tennessee. Thank you for sharing.

-- Learning the wood whisper.

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Tennessee

2860 posts in 2478 days


#14 posted 12-19-2017 09:20 PM

Yes, that is a natural edge on the top. Thank you for your kind comments! It was what they call in Tennessee “Old Growth” where the tree was about as old as it could get. Most of the wood was dark red when they laid it over. When the cutter took the first one down, he knocked on my back door and said he would not cut it up, and would I consider 10 foot long lengths, that he would stack.
I immediately said yes, and a couple months later traded most of them for a truckload of planked walnut. Guy wanted to build his wife a walk-in cedar closet. He planked it, stacked it for a year, and built the closet. I got to see it, it was amazing and the smell! Whooee.
I also got a couple of mantle pieces out of the deal, 10” by 2”, which I still have, and most of one section of 10’ log, about 6’ left of it.

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

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LKaan

11 posts in 123 days


#15 posted 12-20-2017 12:23 AM

Sounds like it’s beautiful wood. Can’t imagine a cedar lined closet, would be a strong scent. I love the smell of cedar.
I’m curious as to what is the preferred wood for guitars and if you have ever seen a cedar guitar? Bet it would be a sight to see.

-- Learning the wood whisper.

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