What do figure and or defects look like on living trees

[maple man]

I am a professional wood worker with over 40 years experience and an amateur forester who has  been pruning and releasing oaks and maples on my 50 acres for about 15 years. I have recently realized that I really don't understand the correlation between what I am seeing in finished lumber with what I see on the living tree or log.

Some things are obvious like waves under the bark produces curl in maple or dimples indicating birds eye within. I also think I understand that sprays of tight birds eye like knots such as are found in willow must be caused by groups of epicormic like sprouts that persist without diameter growth for short periods of time allowing the trunk to grow around them. On oak crop trees which have been released I am pruning off any epicormics in the first or second year that they appear when they are from  1/16' To 1/4" in diameter and am assuming that the resulting defect would be a small pin knot or a tight birds eye type knot which as a wood worker would not bother me at all but I have been told that these may be considered a real defect under some circumstances.

I am interested in hearing from people who buy and cut logs whether they would down grade lumber or veneer that had knots of this size or if you have seen larger or unsound defects from this sort of pruning.

Thanks for your comments

[Ron Wenrich]

Usually, hardwood log buyers have a grading system.  Some are developed around defects, the type and the number.  In my area, a veneer log has to be at least 14" inside bark on the small end.  That means you'll need about a 16" diameter tree to make a minimal veneer log.  After that, they'll check for defect.  Depending on the type of process used to make veneer will yield whether they want the log or not.  It would result in a lower price, provided it wasn't that much of a defect.

When you get to saw logs, many mills have developed their own grading system.  In my area, a tulip poplar needs to be 16" dib to make a #1 or prime.  For the denser hardwoods, that will drop to 14".  For short logs, they have to be pretty clean.  The lumber grading rules don't allow for much defect, and knot placement gets to be critical.  Although a small pin knot may not be much to a woodworker, it doesn't do much if you're making long trim pieces.  Longer sawlogs can allow more defects, as the lumber grading rules will allow you to get enough clean wood to come up to grade.  

For grade sawing, defect placement is critical.  Defect is placed on a corner of a log so it can be sawn out in the edging. 

Generally speaking, the rule-of-thumb is that a bud knot isn't a defect unless it has a dark center.  I have found it is dependent on who is buying the lumber, and how much they need it.  They'll overlook it when they need the wood.  When markets are tight, they'll use it against you to drop the lumber grade.  

Since grade rules vary pretty much from one area to the next, its probably best to talk to a few log graders to see what kind of specs they use.

[mike_belben]

great questions and answers so far, i hope this turns into a long thread.  Stuff i never considered. 

[moodnacreek]

Hard wood veneer log buyers  must have x-ray vision. I have often wondered how they learn it and remember it. And then there is the grade sawyer cutting de barked logs , something I have never done. Hope to see more posts on this subject.

[Ron Wenrich]

I sawed debarked logs for 25 yrs.  A lot depends on the grade of the log, and you can usually tell how good it is just by looking at it.  Butt logs are usually where you have the best lumber.  There isn't as much defect, unless you have some sort of seam.  Put a seam on a corner, and they'll disappear in sawing and edging process.  You may have to turn it a few extra times to keep the seam on the corner.

If you open up and find defect that you wish was someplace else, you can reposition the log.  Nothing says that the original face has to be a final decision.  How much leeway you have depends on logs size.

When you get to second cuts on the tree, there are more pronounced defect and the log flare is gone.  That's where the larger knots start showing up.  Your final destination is going to be a larger piece of blocking.  When you get to the low grade logs, you're looking at making the biggest piece of blocking you can make.  Ties soak up a lot of low grade blocking.

The other thing you have to look at on debarked logs are the ends of the logs.  Sometimes that will hold a lot of secrets as to the inside of the log.  Defect also comes in the form of mineral streaks or pockets of rot.  Often they are evident when they buck the log.  You have about 10 seconds to judge the log when it rolls down the ways onto the carriage.  You'll never get them all right, but after the first 100,00 logs, you'll get fairly decent.

Same goes for veneer buyers.  They have the bark, so they can see some of the figure underneath.  White oak has problems with glass worm and cat faces.  You can see the cat faces in the bark.  The glass worm comes up when you wet the end of the log.  The whiter woods like ash are dependent on the amount of sapwood.  Lots of sapwood is good in some cases.  Also, logs with slower growth will yield a much better grain pattern.  They often look for that.  Color is also important and is evident in the ends.  We used to have to trim ends so the buyers could see it better.

[PA_Walnut]

Great response from Ron...Yoda-truths for sure.

There's a point of note that big/unique and colorful is the new "grade" amongst hobby buyers. They seek big slabs, unique and colorful boards, and with material like walnut, defects are sold as "grain" or "character" and it sells.

I guess it really depends upon if you are ultimately looking to sell logs or lumber, and who your primary market may be.

Enjoy your woods!

[Southside]

Ron,

Just trying to get an appreciation of the scale difference, how long would it take for the sawyer to see those first 100,000 logs?

[Don_Papenburg]

Do you have a picture of catfaces or can explain it . I have never heard that term .  

I have a couple of SPF 2xs and a 6" car siding board that have a very good birds eye figure that I had never noticed in  that variety before .

[maple man]

Ron,
Thanks for your replies. when you refer to "bud knots" is that what will be left behind by a small sprout which only persists for a year or two? Is there any difference if the sprout is pruned off as opposed to dying and falling off on it's own?

[mike_belben]

Im no sawyer but i sit at that splitter and pop a lot of wood open.  I can say for sure that a big old straight looking tree can hide a real ugly young tree inside.   Was just yesterday showing my 5yr old boy a bookmatched piece of sapwood split away from the heartwood, with a perfect straight grained exterior covering a knobby knotty pith.  As the years went on, the sapwood scabbed over the knot and got flatter until it was undetectable by looking at bark or cambium.  But alas, its in there.  Was scarlet oak.

[Ron Wenrich]

Southside  -  It depends how many logs you saw in a day.  For production sawyers, that may mean you saw a couple hundred logs a day.   Some even more.  I think after you get a good year of doing good work, you would be able to have enough experience.  The first few months of experience is loading, turning and dogging to get proficient.  Then you move on to log positioning and after that you start to be able to read your log.

Don - I looked up catface, and it seems that it depends where you're at as to what a catface refers to.  I've seen it referred to as fire damage, which we don't see too much.  Apparently the southeast refers to scars left behind from sap extraction.  In my area, it will refer to a bud cluster.  We find them a lot on white oak, and they are evident on the bark.  We also find them on tulip poplar and sycamore.  Although they may be character wood to some, the veneer buyers and grade lumber buyers will shun them.  

Maple man - My understanding is that when the bud emerges, the knot is present.  That doesn't mean its real deep, and sometimes it won't come out in the lumber.  But, it is nearly impossible to predict.  I've sawn into a patch of those small knots in tulip poplar, in particular.  The next board was clean.  My thinking is this was a stand that was heavily thinned, and that particular tree was left behind.  

Heavy thinning leads to epicormic branching.  Epicormic buds are underneath the bark, and are stimulated by sunlight.  Too much sunlight in a stand will cause the epicormics to pop out.  ts.  They may only be there for a couple of years, then die off due to natural pruning.  But, the defect is there.  It shows up as a black dot in the lumber.  But, if it planes out, it is not considered a defect.  Something I failed to mention before.  So, probably, that epicormic sprout isn't really hurting your timber too much, unless it is excessive.  Pruning it off couldn't hurt.