Colors may be brushed on greenware which is to be bisque fired before applying a covering glaze, or on mature Cone 04 bisque, then covering glaze applied and fired to maturity temperature of the clear glaze.  Color chips were overglazed with LG10 and fired to Cone 05.   For opaque coverage by brushing, the consistency of the color in the jar is correct.  White slip may be tinted by adding small amounts of most colors to produce colored slip. To color moist clay, cut clay into very thin slices, pour color between slices, and wedge until uniform color is achieved.  Since the colors are approximately the same tone before and after firing, the effectiveness of color combinations and blending is observed as the painting progresses. All are AP Non-Toxic in liquid form.  Underglazes are dinnerware safe if covered with dinnerware safe glazes.  If not covered with clear or transparent glaze, should not be used for dinnerware. Recommended covering glazes are Amaco LG9, F10 and HF9. Underglaze #25 will appear Green Turquoise under LG9 and Blue Turquoise under LG10.  Colored transparent glazes in the LG, F and HF series may be selected for unusual effects.  Underglazes may be fired to Cone 10, but some will dis-color.  Glazes with Zinc can cause discoloration of underglazes.  Use of Zinc-free covering glazes is recommended. 
Colors may be brushed on greenware which is to be bisque fired before applying a covering glaze, or on mature Cone 04 bisque, then covering glaze applied and fired to maturity temperature of the clear glaze.  Color chips were overglazed with LG10 and fired to Cone 05.   For opaque coverage by brushing, the consistency of the color in the jar is correct.  White slip may be tinted by adding small amounts of most colors to produce colored slip.
To color moist clay, cut clay into very thin slices, pour color between slices, and wedge until uniform color is achieved.  Since the colors are approximately the same tone before and after firing, the effectiveness of color combinations and blending is observed as the painting progresses.
All are AP Non-Toxic in liquid form.  Underglazes are dinnerware safe if covered with dinnerware safe glazes.  If not covered with clear or transparent glaze, should not be used for dinnerware.
Recommended covering glazes are Amaco LG9, F10 and HF9. Underglaze #25 will appear Green Turquoise under LG9 and Blue Turquoise under LG10.  Colored transparent glazes in the LG, F and HF series may be selected for unusual effects. 
Underglazes may be fired to Cone 10, but some will dis-color. 
Glazes with Zinc can cause discoloration of underglazes.  Use of Zinc-free covering glazes is recommended. 
Glaze - Underglaze - Hearty Ceramic Supply Company
AMACO LUG Liquid Underglaze in aqua comes in a container of 1 pt. capacity and is brushed dipped or poured on leather hard clay greenware or bisque. Underglaze in vibrant color is non flowing and dinnerware safe which makes it ideal for detailing works. It can be covered with transparent glaze to intensify their color and create a smooth surface.
Amaco Liquid Non-Toxic Lead-Free Underglaze 1 PT Warm Green Lug-41
AMACO Velvet Underglaze Pint Leaf Green
AMACO – Cone 05-10 - LUG41 Irish Green – Krueger Pottery Supply
Underglazes by Western, Duncan, Amaco
Velvets tolerate a wide firing range, and can be used on most temperatures and clay bodies. Some colors may fade at high temperatures (cone 7 and up).
Amaco Velvet Underglazes V341 Blue Green , Big Ceramic Store, BigCeramicStore, pottery supplies equipment
LUG-41 Warm Green : (LUG) Liquid Underglaze
Dark Green Velvet Underglaze is a rich green color that is bright and saturated at cone 05, darkens to a forest green at cone 5, and becomes slightly darker at cone 10. A clear glaze deepens the color of the underglaze significantly at any temperature. Pint (16 oz.) bottle.
Amaco Velvet Underglaze 2 oz. Dark Green
BLUE GREEN V-341 2 OZ - The Potter's Shop
LUG-42 Amaco Blue Green - Columbus Clay Company
AMACO Velvet Underglaze Pint Dark Green