We also use to spray on cotton balls for cleaning the eye and mouth area as needed. Some people use powders or corn starch under the eyes and on the moustache. Corn starch is fine, talc is not advised. Some dogs will tear and react to powders of any sort coming near their eyes. So use your own judgment here.
Some people use a baby toothbrush or use their fingers to work the cornstarch in.
A plastic bottle with a pointed snipped tip is okay, too. Do not use boric acid if there is a chance of another dog chewing on the face hair. Don't get into the mouth. It is caustic to the stomach. The boric acid will help dry, whiten and kill germs on the face hair.