Why we boil Madrone

[Ralph Lindberg]

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Only the center of these three pieces of Madrone was boiled. All were cut and handled at the same time, except for boiling.
Obviously something about boiling reduces the amount of strain.

[Reed Gray]

Aw, that takes all the fun out of it!

robo hippy

[Richard Jones]

Wonder how that came about...........

[Reed Gray]

It came about because it is Madrone. Not much of an explanation unless you are familiar with the wood, and I turn a lot of it. I read in Fine Woodworking some years back that Madrone has a way higher water content than just about any wood. We have very wet winters, and very dry summers, and an end of the summer harvested Madrone will sink almost like a stone in the mill ponds. That explains why it shrinks so much. However, the shrinking has never been predictable. Most woods will go into a fairly predictable oval shape. Not Madrone. If you are trying to slab it up for lumber, even if you quarter saw it, consecutive boards can warp in entirely different patterns. Just because. One of the reasons I love it. It is like me, kind of peculiar....

robo hippy

[Christopher Collins]

Wow! Were those all rectangular when they were cut?

[Ralph Lindberg]

Yup Chris, they were
For warp Robo (Reed) needs to post a photo of the bowl he brought up here last month, it looked like one of those glass bowls with the wavy edge.

Madrone can be almost 50% (by weight) water when harvested. It's not that it's that dense (although it is dense) it's wood plus lots of water that makes it heavy.
Plus, when it's boiled (which Robo doesn't do much) it gains even more weight. I've had Madrone gain 25% additional weight, although that was a little dry. Even wet Madrone gains some additional water when we boil it.

[Richard Jones]

...................Madrone has a way higher water content than just about any wood.............

robo hippy

That makes sense. Thanks.

[Reed Gray]

I can't remember exactly, but the article in Fine woodworking said wet madrone had a moisture content or reading of over 70% compared to other woods which were in the 50 to 60% range. It does explain the excessive warping, but not why it never seems to warp to any particular pattern or consistency. A mystery.

robo hippy

[robert baccus]

Actually woods over 100% MC are not rare. I suspect Madrone and others are changed chemically(sap) by boiling. I know green woods react differently than woods that have been in water for several years or centries.

[Reed Gray]

The boiling is supposed to rupture the cell walls so the 'bound' water can escape, or some thing like that. The free water come out fairly easily. It is the stuff at the cellular level that creates problems. I think it also does some thing to relax the lignum or what ever it is that links the fibers together.

robo hippy

[robert baccus]

Actually wood can be compared to a bunch of thickwalled soda straws glued gum. However there are a thousand variations as any kiln operator will tell you. Free water is that in the straws--bound water is that which saturates the soda straw wall(cellulose mostly) . Free water escapes easily and is what causes wood to split first. Bound water has to travel through the cellulose and lignin to escape much slower. The chemicals in this sap, resins, gums ect differ greatly. Think amber and chewing gum. As the strength of boiled wood vs green wood is little affected I doubt the boiling does anything but dilute the saps. With madrone who knows--goes by it's own rules like sweetgum. SG heartwood is very stable compared to sapwood and is sold as satin walnut in the trade. ???

[Leo Van Der Loo]

Robert Baccus is right, the boiling does not do any damage to the wood cells, what it does is give the lignin that does hold these cells (straws as Robert calls them) together and makes them stiff, more pliable and become more like molasses and so the tension in the wood is relieved and relaxed as these cells are now able to move, though it does take time and high enough temperature do have it happen.

[Reed Gray]

I think that the 'water content' percentages given are weight ratios. So 60% would mean that of the total weight, 60% of it is water. This is a different measurement, I think than the % that we use to determine wetness or relative humidity of the wood when we are talking about it being dry enough to be stable. Not sure though.

robo hippy

[Karl Stowe]

I air dried some 2" slabs and they went everywhere. So I cut them up on the bandsaw into pen blanks and it works great. Nice looking burl. Only issue is the round holes in the burl eyes but that is easily filled and sanded with CA glue. Next time I want to cut them into small blanks, not big round flat slabs, and boil them. Just need to take the tracked bobcat back to my source. I can even get some manzanita burl balls.

Karl