CARVER’S QUESTION:

Q: I’m wondering at what point in your career you could look at a picture and visually picture it in wood? My question may sound unusual, but I consider myself a beginner after 7 years (it’s more than a hobby, but not a full time job) and yet this weekend I find myself looking less at the picture, and more at my next stroke with the gouge. Just curious on your thoughts.

A: That’s an excellent question. I think of it more of an evolution than an AHA! moment. For me the key was understanding that I was doing a carving (drawing, painting) and not a duplication of nature. When my subject was a leaf, for example, the result of my effort was a carving, not a duplicate leaf in wood. The object from nature was the beginning point, not the end point. I was then free to interpret, exaggerate, stylize, add, omit–do anything I wanted to as an artist. My concentration became the medium itself, and the process–what I could do with the material–rather than slavishly trying to duplicate something in front of me. I used the objects in nature as a means to arrange forms, play with textures, mess around with depths, in other words play around. It’s important to throw the critic out of the room–just mess around with the materials and have fun.C140 NestingQ
Not a real tree, not real leaves, not a real bird, just an arrangement of forms in, to me, an interesting pattern of shapes, layers and textures borrowed from (BUT NOT A SLAVE TO) those found in nature.

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Follow-up Question from cupping blog below:

Q. Dang it, Ivan, your explanation of cupping is really complicated. You don’t have to start your explanation with Adam naming the trees in Eden! Can’t you pare it down a little?

A. Well, OK, Ivan, I’ll try. Those “it depends” explanations can get complicated. Trouble is, no two pieces of wood are alike, and the precautionary steps that will work for one, carving in from the heart side, for example, will not be enough for another. Many plaques will be just fine carved sapside down. Others, from the quarter-sawn section of the log will probably be stable no matter how you carve them. Those from the “B” section of the log (see illustration below) will probably cup unless you laminate them, flip-flopping the grain. It is always a good idea to “leave more wood than you take away,” not just to prevent cupping but for the general stability of the carving through time. Whew! (See blog below for the windy explanation of all this.)

CARVERS’ QUESTIONS:

Q. What can I do to prevent warping of some of my relief carvings? I add kerfs to the back, make certain I am carving on the proper side, and still some of the carvings warp. I use basswood almost exclusively, and most of my carvings are 8 X 10 X 1 inch.

Ivan sez:
Two important points here: Wood is a “living material.” It expands and contracts in response to the temperature and the humidity of its environment. Secondly, we’re dealing with a rectangular plaque cut from a circular tree with a variable ratio of sapwood to heartwood, depending on the size of the tree and the part of the tree the wood is cut from. Different boards from the same tree will cup at differing rates in different places. The main cause is “differential shrinkage” based on the position in the log each board is sawn from. In the hardwoods, tangential shrinkage is greater than radial shrinkage causing plain-sawn boards to cup towards the outside of the tree.
001  Log view
Of course you can use only boards with the rings 90 degrees to the surface of the board (quarter sawn) as A. However, quarter sawn wood is expensive. The generally available wood is plain sawn, or flat sawn, a good portion of it prone to cupping.

That said, there were several precautions that traditional carvers took to limit the checking and the cupping of their reliefs:
1.Leave more wood than you take away. Rule of thumb, the deepest point of the carving should be less than half the thickness of the wood. That may reduce some cupping but primarily keeps the thin parts from checking as the wood expands and contracts through the seasons. We know the thin parts shrink/expand faster than the thick parts, so avoiding extremes lessens the stresses which lead to checking.
2.On single boards (plaques that are not glued up), carve from the heartwood into the sapwood. (Put the cupped side against the bench, the convex side up.) A board cups towards the sapwood, and since a board may also cup towards the carving, the two forces may cancel each other out. I use “may” here a lot because, as above, the position of the board in the log dictates most of what happens to it.
3.On larger plaques, laminate the wood, flip-flopping the grain. A wide board can cup substantially, so to minimize the effects, it is cut in half or in thirds, depending on its width, the sapwood/heartwood directions are alternated so that the tendency of one segment to cup is counteracted by the opposite cupping of the next segment.
004 laminate
4.Carve away wood in the back of the carving to balance the stresses. This can work for some of the thicker carvings, but can be counterproductive if removing wood from the back gives you very thin areas that dry much faster than surrounding wood.

ILLUSTRATIONS:(Click to enlarge)

Here is a basswood board showing the tendency to cup towards the sapwood.
002 figure

This carving was from a single board 9 1/2 inches wide. Even though it was carved sap side down, following rules 1 and 2, it still cupped. The growth rings show that the board is from the B position of the log above, prone to cupping. 003 figure4
This carving, on the other hand, shows no cupping because it was laminated, alternating the sapwood/heartwood.
005figure2NV
MY PERSONAL EXPERIENCE:
If the plaque is under eight inches wide and I don’t mind a little cupping, I’ll carve it sap side down, “leaving more wood than I take away.” This generally keeps the plaque fairly flat. However, if the plaque is wider than eight inches, and especially if the board is from a less stable section of the log, as shown by the pattern of the growth rings, I’ll laminate it, flip-flopping the grain. I’ll also leave more wood than I take away. That has proven the best precaution against cupping. I’ve done many reliefs using these two techniques through the years. Laminated reliefs that I carved 40 years ago still show no signs of cupping or checking.
OTHER SUGGESTIONS:
Make sure the wood is dry and acclimate it to the shop environment before you work with it. Wood that has more moisture than the environment will lose it faster in freshly cut areas and therefore will cup even more into the carving than it would if dry.

Keep in mind that Wood shrinks and expands side to side more than it does the length of the grain. A large plaque can shrink or expand several inches throughout the alternating wet summers/dry winters. If put in a frame, the carving should “float”–that is set in a way that gives it space to expand and contract. (I once got a call from a church about an altar screen that would crack in the winter. They would fill the cracks, only to have them reappear the next winter. The solution to the problem was easier than they realized. After I explained that wood is a “living material” and needed space to expand and contract, they realized that the screen had been mounted wrong—someone had anchored all four corners against the wall. In the winter the carving shrunk but the wall it was mounted on didn’t. By slotting the mountings to let the screen float, the opening and closing of the cracks was eliminated.)
I’ve talked to carvers who said they’ve straightened boards by putting them concave side down on the grass. The sun dries out the top side and the grass adds moisture to the bottom. I’ve not tried that, though my concern would be that the cupping might eventually return. I’d prefer glue the plaque up for long term stability.