You could glaze these so many ways..
1. Paint a blue, green, brown or black stain over them, then sponge the
stain off. The dark blue, or whatever color will be in the recessed
areas, and the rest of the piece would be lightly stained with your stain
color. Then you could brush or dip them with clear to make them shine.
2. You could choose "semitransparent" colors to paint over them. Opaque
colors will be all the same color all over, and details will disappear,
but semitransparent or transparent colors will appear darker in the
recessed areas, like veins, or around your pressed leaves, giving your a
nice contrast in color. You would need to experiment with glazes to find
some good layering colors, as some work out beautifully together and
others are disasters.
3. You could paint the leaves one color and the bowls another color. Or
you could paint the bowl with three layers of a color and then brush a
fourth layer over the leaves (or paint the third layer on the leaves with
a new color and the third layer on the bowls with a different new color)
4. You could underglaze the whole thing and use squeeze bottles to slip
trail leaves, outlines, dots, etc. then apply clear glaze. (You have to
prefire underglazes before you apply the clear glaze, though.)
5. I have had gorgeous results with older children using Duncan black
"French dimensions" squeeze bottle black glaze to outline things, add
dots, details, and so on. It creates a raised black line that does not
bleed into the glaze color. You need to fire the French dimensions lines
on first and then apply transparent or semitranspparent colors over the
whole bowl. The black lines will pop through the glaze. It actually
works BEST with a glaze like Duncan Concepts or Mayco Stroke and Coat over
the black lines.
6. You could do majolica glazing on these bowls....Buy a white majolica
glaze, put on three coats. Let it dry to the touch. Mix up some majolica
decorating colors (amaco sells some lovely ones.) They get painted on
like watercolors, right on top of the white glaze. You can layer with
them and get beautiful effects. It looks especially nice over a terra
cotta colored clay body, as the warmth of the brown clay through the glaze
is characteristic of great majolica. WOrd of caution..l do some test
tiles of the decorating colors to see how they perform...they are VERY
concentrated. Some of the colors really need to have at least some water
added to them, or they will be dry and chalky when you take them out of
the kiln. It just takes experiementing. It is also really great to add
some thin brushed black lines to the colors...like outlining parts of
shapes, etc. You want a range of dark and light colors in majolica.
Have fun and good luck. Makes me want to make some leave bowls.