Combine the sugar and water in a heavy saucepan. Bring to a boil while stirring.
Add the glucose syrup and cream of tartar, if using. Cook to 156°C/313°F without stirring.
Pour the mixture onto an oiled marble slab. Add the coloring and citric acid, if using.
Turn occasionally as the batch cools to a plastic consistency. Add the flavoring and pull as desired.
Jacket, form, and cut as desired.
To stripe the candy
Pour two pools of sugar onto an oiled marble slab: one 80 percent of the batch, the other 20 percent.
Pull the larger pool until it is white.
Add a strong dark red color to the smaller pool and pull very little, so as not to lighten the color.
Keep both sugars warm under a warmer.
Cut the white sugar into two pieces, one twice as big as the other. The larger piece will be the center of the candy; the smaller piece will be the white part of the jacket.
Roll the center into a stump 20cm/8in long.
Flatten the white jacket sugar into a ribbon 8cm/3in wide and 20cm/8in long.
Fashion the red sugar into a narrow ribbon 25mm/1in wide and 20cm/8in long.
Attach the red and white ribbons side by side.
Pull the ribbon to double its length and cut it in half crosswise.
Reattach the ribbon with alternating colors adjacent.
Pull again to double its length and again cut it in half.
Reattach the ribbon, joining the red to the red.
Pull again to double its length and cut it in half once more.
Reattach once again, white against white.
Place the center onto the ribbon and wrap it to jacket. Seal the jacket tightly around the center.
Pull the jacketed log into a rope of the desired diameter. Cut and shape it as desired to make canes, sticks, pillows, or lollipops.