Types of Burrs

[Dave Fritz]

Some friends had a dead burr oak tree that was covered with knobs and burrs. Of course they called them burls which they are not if indeed a burls must contain eyes. These seem to be layers of growth over and around branches. As such they aren't very stable and will come apart easily.

Does anyone know of a reference explaining and naming different burls, burrs and/or other tree growths?

 

[Bill Boehme]

For anybody not familiar with bur oaks they are a type of white oak. They have huge leaves and acorns that are larger than golf balls. We have several of them in our back yard and I have also planted some in the park next to our yard. They are majestic giant trees.

The difference between burr and burl is a couple thousand miles of ocean. What the Brits call a burr is exactly the same thing that we call a burl. True burls (or burrs, if you're British) are rare on bur oaks (or any oak for that matter). Note that the name of the tree is spelled with just one "r".

Sometimes oaks will develop a very large burl-like growth where a limb once existed, but has completely healed over. These knots can produce some beautiful wild figure that is well worth turning despite being extremely hard if the tree has been dead for a while. I turned a hollowform from a live oak knot/burl/burr ... whatever you choose to call it, it's beautiful wood.

I'm not sure what you mean by eyes unless you mean a knot on an oak that has a large number of twigs growing out of it.

 

[Dave Fritz]

Thank you for the reply. I was under the impression that to be called a burl in the US the wood had to contain eyes which are typically close to the bark. Maybe that's just a good burl or burr.

Thanks so much again for your reply.

 

[hockenbery]

Some friends had a dead burr oak tree that was covered with knobs and burrs. Of course they called them burls which they are not if indeed a burls must contain eyes. These seem to be layers of growth over and around branches. As such they aren't very stable and will come apart easily.

Does anyone know of a reference explaining and naming different burls, burrs and/or other tree growths?

There are healed limb scars sometimes called cats eyes on most large trees that are not burl but where a limb broke off and was later grown over with wood and bark. These are often hollow. I particularly like these for the natural edge openings of hollow forms

Maple hf limb scar allows the pitcher lip. About 13" diameter


Camphor hf with dramatic rim from a limb scar and a less than great shape. Needed a little more height on the form but the wood was no there. About 9" diameter.




Maple burl HF about 12" diameter

 

[john lucas]

there is a burl about 50 feet up in my neighbors tree. We are expecting high winds tonight. Not that I'm wishing them any harm but if the tree falls in the right direction that burl is mine. I'll simply volunteer to help him remove the wood and of course that piece will dissappear. Not all burls have any figure. I waited for years for a tree on campus to come down. When it did I got a piece of the burl and it had grain just like the rest of the tree. Bummer. Sometimes it's hard to tell a burl from a limb grow over. At least from the outside but when you cut into them it's totally different kind of like what Al showed.

 

[Bill Boehme]

Despite the burl like appearance, this is actually a limb scar from a live oak. It was partially hollow with lots of black pith wood that made for some interesting interrupted hollowing in rock hard wood.

 

[Dave Fritz]

This is also from a limb scar. This is the tree: http://news.wisc.edu/last-stand-of-the-presidents-oak-a-trees-life-remembered/



The bur oak I'm now working on isn't as solid as this was. I'll try and get some pictures after it quits raining.

 

[Tom Albrecht]

Despite the burl like appearance, this is actually a limb scar from a live oak. It was partially hollow with lots of black pith wood that made for some interesting interrupted hollowing in rock hard wood.

That is the weirdest hunk of wood/ bowl I've ever seen. It looks like a glass bowl full of vermicelli.

 

[Bill Boehme]

I'm sure that I will never get the chance to see anything like that again. There's no point in waiting for a live oak to die because they can live a thousand years.

I decided to not put a finish on it so I just sanded with Micromesh all the way to 12,000 grit.That was about five years ago and it still looks great. The opening at the top was the natural opening where the old broken limb was. The interior was about half hollow. The interior was too hard to hollow until carbide tools came along. Also the opening was sort of splintery like a bunch of fingers pointing towards the opening. That is why I have all that turquoise Inlace on the top. On the inside around the opening I built it up with epoxy and wood splints. Once I got the interior mostly turned to an even wall thickness I was able to turn away the splints and epoxy. It doesn't have a foot ... just a gently rounded bottom and fortunately it sits perfectly straight.

 

[Dave Fritz]

Here's a picture of a piece.

This is the underside.

This is a different piece but is typical of what the inside looks like

Do you think those are caused by overgrowth over an old branch?

 

[Dave Fritz]

I think this is what it is: http://www.walterreeves.com/gardening-q-and-a/oak-gall-on-trunk/