If you color an entire wooden table one smooth shade of brown, it will certainly be brown.
Whether it looks like wood is another question.
Wood gets its character from variation: grain, knots, streaks, scratches, changes in color, and the direction those marks travel. Even a polished piece of furniture usually contains subtle shifts from gold to red-brown, gray, cream, or deep chocolate.
The trick is to build the wood first and the brown second.
Before adding detail, decide which direction the grain should travel.
On a long plank, it generally runs along the length of the board.
On a table leg, it follows the length of the leg.
On a round cut log, the grain may form rings.
On a tree trunk, it follows the growth of the tree, twisting and changing as the trunk bends.
Your pencil strokes should reinforce that direction.
If the wood grain runs vertically but you color everything with obvious horizontal strokes, the two ideas begin fighting each other.
Let the pencil travel with the material.
Don't begin with dozens of dark brown squiggles on white paper.
Start with a light base layer.
Depending on the wood, that might be:
cream,
pale ochre,
gold,
tan,
light brown,
muted orange,
gray-brown.
Apply it lightly in the direction of the grain.
Then introduce one or two additional colors in irregular areas.
Perhaps gold in one section.
A little reddish brown elsewhere.
Some gray near a weathered edge.
Now you already have variation before you've drawn a single grain line.
Draw three long rectangles.
Turn the first into fresh pale wood using cream, ochre, gold, and light brown.
Make the second rich dark wood using warm brown, red-brown, burgundy, and deep brown.
Make the third weathered wood using gray, muted brown, cream, and perhaps touches of cool blue or green.
Add grain to all three.
Keep the same basic drawing.
You've just created three entirely different materials using changes in palette, contrast, and texture.
Wood grain isn't a collection of perfectly parallel lines.
Let some lines curve.
Let some split.
Allow others to disappear.
Change their thickness and pressure.
Add occasional elongated loops around knots.
Place several lines close together, then leave a quieter area.
You want organized irregularity.
If every grain line is evenly spaced and identical, your antique oak table may begin resembling a barcode.
Knots are wonderful little focal points.
Begin with an irregular oval or circular shape.
Add curved grain lines wrapping around it, almost like water flowing around a stone.
Darken part of the knot and allow some grain lines to emerge from it.
Don't make every knot perfectly round.
Don't put one every three inches.
A few irregular knots will suggest natural wood much more convincingly than a carefully scheduled knot convention.
The same grain can look very different depending on the surface finish.
For polished furniture, keep your base layers smoother. Use more subtle grain, richer colors, and perhaps a broad soft highlight where light reflects from the finish.
For rough barn wood, leave more visible pencil texture. Add broken grain, cracks, scratches, uneven edges, and stronger variations in color.
For unfinished wood, use lighter, softer colors and relatively subtle grain.
For old painted wood, let the underlying grain appear only in selected areas where paint has worn or chipped.
The object tells you how much texture it needs.
Draw or trace two identical wooden doors.
Make the first newly finished.
Use warm, even layers, restrained grain, clean edges, and a gentle polished highlight.
Now make the second look as though it has been standing at Edenglow Manor since approximately the invention of doors.
Add:
darker uneven grain,
gray weathering,
small cracks,
worn edges,
subtle discoloration,
scratches,
and deeper shadows around the panels.
Same door.
Same basic brown family.
Completely different history.
Texture can tell a story before you've written a single word.
Try layering unexpected colors.
Warm wood can contain yellow, orange, red, burgundy, or violet.
Weathered wood can contain blue-gray, lavender, muted green, or charcoal.
Old damp wood might develop subtle green tones.
Sun-bleached wood may move toward cream and gray.
Mahogany can contain deep red.
Cherry wood can glow with warm reddish orange.
Walnut can move into violet-brown.
Don't worry about matching an exact species unless realism requires it.
Coloring books give you permission to invent a rather impressive number of trees.
Wooden objects still have three-dimensional form.
A table leg needs shading around its cylindrical or rectangular shape.
A carved panel needs darker areas inside recesses.
One board overlapping another should cast a small shadow.
A crack may be darkest in its deepest section and softer toward the edges.
Don't let the wood grain distract you from the underlying object.
First establish form.
Then allow the grain to travel across that form.
Draw four identical wooden planks.
Make one:
New
Old
Burnished and polished
Weathered and abandoned
Use similar brown pencils for all four.
Change primarily:
pressure,
color temperature,
amount of grain,
scratches and cracks,
smoothness,
highlights,
and contrast.
Now ask yourself what each plank seems to have experienced.
If they tell different stories, you've successfully used texture as more than decoration.
Just as we don't need every hair in a furry animal, we don't need every fiber in a wooden board.
Put stronger grain where you want interest.
Let some sections remain relatively quiet.
The viewer will understand that the entire object is wood without requiring documentary evidence from every square inch.
This is especially important in a busy coloring page.
If the wooden table, wooden floor, wooden wall, wooden chair, wooden shelves, and wooden picture frames all receive elaborate dark grain, the entire scene can become visually noisy.
Choose your moments.
Let the grain follow the object, then let imperfections interrupt the grain.
Begin with directional layers. Add color variation. Introduce a few knots, streaks, cracks, or scratches. Deepen the shadows last.
The goal isn't to draw brown lines.
It's to create something that looks as though a tree had a very long and interesting second career.