Soak a cloth in denatured alcohol, and rub the cloth over the poplar to clean the wood.
Dip a paintbrush into a medium dark stain, and use the paintbrush to coat the poplar with the stain evenly. Leave the stain on the wood for five to 10 minutes.
Wipe the stain off with a cloth in a light and rapid manner so the stain's color is even.
Apply another coat of the medium dark stain to the darker parts of the poplar. Apply the stain in an oblong and uneven pattern to match the look of natural hickory. Wipe the stain off after five to 10 minutes. When finished, some areas of the wood will be darker and some lighter.
Apply a coat of sealer over the poplar with the paintbrush once you achieve the desired color for the wood. Allow the sealer to dry completely.