New to turning green wood

[Bernie Kopfer]

Last week I obtained some large piecEs of sycamore that had just been felled a couple of days previous. Due to various factors I am unable to have someone come over and instruct me in how to select and and properly prepare turning banks etc. So after watching some videos and reading I just went ahead and laid out what seemed reasonable. Ended up with many blanks ranging from few inch diameter to some 12x12 cylinders. Some for platters and who knows what else. I coated all oF them completely with Craft Supplies’ Artisan Woodsealer.
My intentions are to turn them as I have time to rough shape and recoat completely and let them dry thoroughly and then final turn... Is this a Good way to go? And is one coat of sealant over everything sufficient? It was fun selecting and cutting the blanks but I don’t want the work to go for naught. Any advice and pointers will be appreciated.ignorance is not bliss!

[Prashun Patel]

Working with green wood is an art as much as a science. I maximize my chances for success by doing the following:

1) Keep the logs as long as possible and ends sealed until you can get to a lathe within a couple days.
2) When you are close to being able to turn them, cut each section into a 'D', taking care to remove the pith (as much as you can reasonbly spare).


You can then mount that D directly to the lathe, or you can cut the bark side flat, and cut the corners off into an octagon, or even cut it on the bandsaw to a round. Once THAT happens, I'd really get it on the lathe fairly quick or at least seal the ends. How long the blank will remain before it starts to check again is a function of how close you are to the pith, how much sap wood vs heart wood is there, and the species.

Rough turn it to a uniform thickness. Take time to caliper it. Especially near the bottom where my tendency is to be thicker than the rim. It doesn't have to be precise, but I try to get the thickness about 10% of the diameter. For bowls smaller than 8", I'll go no thinner than 3/4".

Keep your rough turned bowls away from a lot of air circulation at first. Wthin the first month, check for mold and cracking or checking. If you get mold (with sycamore) you can spray a little bleach on them. For most other species, taking it into the sun periodically can help. After about a month or two, you can usually leave them unattended for the next few months. If you have a garage and a basement, you might consider storing the rough outs in the garage for the first two, then in the basement (which is generally dryer) for the remainder.

Something to try: For one section of a log, you get two "D's". Turn one with the opening on the pith side and the other with the opening on the bark side (not necessarily live edge). This will give you a good understanding of how the grain orientation can be manipulated.

If your logs are wide enough, instead of making them all "D's", you can quarter saw a couple into 4 smaller QS blanks. Those will turn, dry, and look quite different from the others.

There is a tendency @ first to want to make the bowl as large as possible to utilize the max amount of the log. Eventually I realized that the orientation is way more important than the size.

[Bernie Kopfer]

I've already not done #1. The logs have been cut into various sized "D"s" without the pith. Because they are thick they will take forever to dry, so I intend as time allows to turn them into roughed out bowls. Will doing this over the next couple of moths create problems within the wood?

[Prashun Patel]

Art and science.

It may or may not. I've done as you did in the past. What I said below is a general way I do it now. The sooner you can get to turning them the better. But don't put too much pressure on yourself. A checked log is just a smaller bowl...

[John K Jordan]

I've already not done #1. The logs have been cut into various sized "D"s" without the pith. Because they are thick they will take forever to dry, so I intend as time allows to turn them into roughed out bowls. Will doing this over the next couple of moths create problems within the wood?

One time proven way to store blanks indefinitely until you are ready to turn is “ponding”: submerse in clean water. Change the water often. Another way is to wrap in plastic and freeze. But best to turn them soon.

If you have to quit for a bit while turning, say for supper or overnight, spray the work with water and cover with plastic.

When roughing be sure to leave enough wall thickness to turn round after the wood warps by drying. Someone with experience with that species might advise. Also, don’t leave the roughed out bottom too thick or it is more likely to crack.

Another way to treat a roughed our bowl is boil it, at least 1 hr per inch. This can relieve stresses, reduce or eliminate cracking, and reduce warping. It really works.

That said, I rarely turn green anymore. I prefer to cut blanks, seal well, and let them air dry first (indoors in conditioned space). It doesn’t take forever but seems like it. I have fairly large bowl and vessel blanks ready to turn that I cut green 15 years ago or longer. Cut a few now and then and eventually you’ll have more than you can use.

[Bernie Kopfer]

John would you explain what you mean and how you go about sealing well.

[John K Jordan]

John would you explain what you mean and how you go about sealing well.

I use thickened Anchorseal. I thicken by pouring some in the container I use for brushing but leave the lid off for at least several days so some of the water evaporates. I use a plastic coffee can for the Anchorseal, and keep a brush in the can with an inch or so of Anchorseal.

Where on the blank I seal depends on the blank. On rectangular blanks I seal all end grain. If the grain is wild, twisty, or burl, the end grain can be on any side. I seal flat sides that are parallel or mostly parallel to transverse rings since this is often where the blank cracks due to the higher shrinkage (the T/R ratio). I seal sides that have a junction of heart wood and sap wood since differential shrinkage rates can cause cracks there. This is especially a problem with certain species, notably dogwood. I seal sides that may contain juvenile wood, close to the pith as evident by the curvature of the rings.

If I cut the blank round (or octagonal) for a bowl or vessel I seal all the way around. When I rough turn a bowl blank I seal the entire outside and put it on the shelf to dry a few months.

It might sound like I seal every square inch and I do on occasion, but most blanks have four sides unsealed. The idea of sealing is to slow down the moisture leaving the wood. If it leaves too fast in one area, most typically the end grain, a strong moisture gradient can develop between the surface and a little further back in the wood. The more rapid shrinkage of the drier wood at the surface is what causes many cracks. A coat of wax slows down the moisture leaving that surface giving moisture deeper inside the blank more time to migrate to the drier area, reduce differential shrinkage, and reduce the chance of cracking.

Coating the entire blank on all sides is the best to equalize the moisture gradient but at the expense of increasing the total drying time. If you buy exotic wood turning blanks you may find they are coated on all sides with wax. The importers and dealers often dip the blank into a vat of melted paraffin wax resulting in a heavy coat. This helps insure the blank doesn’t crack before the sale but means the wood is probably wet and also will take a long time do dry. I have big blocks of olive wood and other species coated like this and I monitor the weight to track the drying. When I judge the blank to be partially dried (maybe 1/3 to 1/5) I usually scrape off most of the wax with a cabinet scraper to speed up the drying. Cracks are less likely to form after the wood has lost a significant amount of water.

Note that after cutting and sealing blanks I put them on wire shelves and sometimes in loosely stickered stacks for drying. I inspect larger blanks after a few weeks and cut away any cracks I find before they can get deeper. I’d rather have a smaller blank than a cracked one.

Note also if I do decide to leave a minor defect, say a small crack in one end of a turning square that could be the end gripped in the chuck, I mark it with red sharpie before sealing so I won’t overlook it and have an unpleasant surprise at turning time.

I also sometimes wrap bowl blanks in plastic wrap if I plan to turn them green or partially green. The danger with this is fungus can grow and the wood can decay if the temperature is warm enough. The delight of this is the blank can spalt, sometimes beautifully.

I recommend the book “Understanding Wood” by R. Bruce Hoadley to, well, understand wood and how it dries. (and much more)

JKJ

[Bernie Kopfer]

Thank you John for a thorough explanation of sealing. Turning green is whole different world than nice dry sticks and blocks. Much is said about sealing end grain but after cutting and trimming it can be difficult to identify. I’m having too much fun cutting up blanks and now doing the first rough turn. After this much work it would be a shame to lose the piece due to improper sealing or storage.
Must say that the idea of a large cauldron of boiling water with large pieces of wood bubbling around in it is intriguing.

[John K Jordan]

Thank you John for a thorough explanation of sealing. Turning green is whole different world than nice dry sticks and blocks. Much is said about sealing end grain but after cutting and trimming it can be difficult to identify. I’m having too much fun cutting up blanks and now doing the first rough turn. After this much work it would be a shame to lose the piece due to improper sealing or storage.
Must say that the idea of a large cauldron of boiling water with large pieces of wood bubbling around in it is intriguing.

You might look at some of Stephen Russell's articles on turning green wood and boiling. Steve is the King of Boiling. Unfortunately his web site is no longer there. Fortunately all the articles are available on the Wayback Machine, the internet archive, although the response time is not snappy at times. His main articles page:

https://web.archive.org/web/20171003...-articles.html

Look on this page for "Basic Procedures for Turning Green Wood Bowls"

Then "Boiling Green Wood to Reduce Drying Degrade (Part 1 and 2)" and "Tips for Better Boiling"

There are many other articles worth reading on that page, and more if you back up one. A tremendous resource. Steve recently retired and said he hopes to get his web site up again

The late Jim King who exported bowls and blanks from Iquitos Peru told me they boiled every roughed bowl and recommended boiling rare, exotic blocks I got from him. Boiling there was in a 55 gal drum over a wood fire.

I think more people turn green wood than dry because it is great fun to watch long chips fly and because it is far easier and can be done with beginner's skills. Many get on the well-traveled path of turning bigger and bigger bowls and hollow forms. Part of this is because green wood is readily available and cheap or free in many parts of the country while dry blanks can be expensive and limited in size (or take a long time to dry!) I personally find more challenge and satisfaction in turning smaller, detailed things, all from dry wood.

Cutting and drying blanks from green wood is one of my favorite things to do. I have a woodmizer sawmill that I use to break down the big stuff but do most of it with a chainsaw and 18" shop bandsaw. There has been a lot of interest in this in our club and so far I've had six classes in my shop.

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JKJ