Many supermarkets coat fresh vegetables with an edible wax. Vegetables that store poorly, like cucumbers, are the types typically waxed. The wax prevents moisture loss from the cucumber during transport and in the days leading up to purchase, but it also gives the cucumber an unnatural glossy green sheen. An unwaxed cucumber is dull green in color and doesn't have a glossy skin. If you prefer to remove the wax, do so immediately before using the cucumber since washed cucumbers may not store as well as those left unwashed.
Wash the cucumber in cool water, rubbing the skin of the vegetable with your fingertips. Cool water doesn't remove wax, but it ensures there is no harmful bacteria on the surface of the cucumber.
Mix equal parts water and vinegar together in a small bowl. Submerge the cucumber in the solution for one or two minutes.
Wipe the vinegar solution off the cucumber skin using a rough cloth. Rub vigorously as you dry to remove the wax coating, which the vinegar loosened.
Rinse the cucumber under cool water to wash off any loosened wax and the remaining vinegar solution. Slice and use the cucumber immediately.
Some wax may still remain on the cucumber after washing it in vinegar. If in doubt, peel the vegetable before serving it.
You don't have to remove the wax to make pickles. Instead, poke holes in the cucumber with a fork so the pickling mixture can penetrate the interior of the cucumber.