Lay a drop cloth on the floor below the pine-covered wall. Cover each window with newspaper, using masking tape to hold the newspaper in place.
Remove all electrical outlet and switch covers on the pine-covered wall, using a slotted screwdriver to loosen the cover's mounting screws. Protect each outlet and switch with a piece of masking tape.
Sand the surface each pine board with a medium-grit sanding pad, working the pad with the wood's grain. Remove all splinters, rough spots and contaminants from each board's surface. Clean the sanding dust from the pine wall, using a hand broom.
Smooth the pine wall's surface with a fine-grit sanding pad, pushing the pad with the wood's grain. Continue to work the fine-grit pad until the entire wall has a uniform appearance. Do not touch the finished pine with a bare hand. Clean the dust from the pine wall with the hand broom.
Apply a wood colorant to a small section of a pine board, using the colorant-manufacturer-recommended paintbrush to apply a thin coat of the colorant to the board's surface. The type of paintbrush depends on the type of colorant. Verify that the pine board accepts the colorant without changing hues. If the colorant changes hues, let the colorant dry and sand the colorant from the pine's surface before testing a different brand of colorant.
Cover a pine board with the wood colorant, using the paintbrush to spread the colorant. Work from the top of the board toward the bottom. If the colorant starts to run, catch the run with the paintbrush and blend the excess colorant into the surrounding area. Coat the entire length of the first pine board, then move to its neighboring board. Repeat this across the entire pine-covered wall.
Let the colorant dry, following the colorant manufacturer's recommended drying time instructions. Apply additional coats of colorant until the pine wall reaches the desired tone, using the colorant manufacturer's directions as a guide. Let the colorant dry completely before continuing.
Clean the paintbrush, using the colorant manufacturer's cleaning directions. If you're using a water-based colorant, clean the brush in clean water. If you're using an oil-based colorant, clean the paintbrush in mineral spirits.
Coat a pine board with a colorant-compatible clear coat, holding the paintbrush at a 45-degree angle to the pine wall. Run the brush from the top of the board toward the bottom. As the brush reaches the bottom of the board, whisk the brush tip away from the pine. Apply clear coat to the entire board, then move to its neighbor. Repeat this across the pine wall. Use water-based clear coat on water-based-colorant-covered walls and an oil-based clear coat on oil-based-colorant-covered walls.