The mouth atomizer is what was used long ago before spray cans were invented! It can be very useful to marblers, but it can be a tricky little tool to use too.
It is used most often to make the Italian Vein pattern, which requires a fine spray of gall water over the surface of the size, to break up the colors into thin veins. To do this, put about a teaspoon of water in a small jar, such as a baby food jar. Add several drops of gall, 10 or more at least. Now put the long end of the atomizer in the jar. Put it against the far side of the jar, and hold it there by putting your thumb inside the jar. The mouthpiece should be facing you. Hold the shorter end with your other hand. Tip the jar forward so the long end is in the liquid. Make sure the tool is opened to a full 90° — if it is even a little bit less than fully open, it won’t work. Now blow through the mouthpiece, hard! A short, quick blast of breath works better than a long steady breath. A spray should result. You have to use a lot of breath, and really blow hard.
The atomizer can be used to spray paint too. The paint must be rather thin, usually with extra gall added. You have to blow even harder with paint! Rinse it out afterward very well — paint will clog it very quickly.
The atomizer is necessary for making
the Italian Vein pattern.
It is also used for making the tiny "stars", or white specks, on patterns such as Straw Blown and the Space Marble.
It is used to spray the smallest specks of color on Stone Marbles such as the pink and yellow examples here.
And it is used in making the small dots of color on the Antique Spot pattern.
It is especially useful in making the second layer, the transparent one, on Overmarbled papers.