They are rich colors and can be used for all over coverage similar to an opaque underglaze.  Colors may be mixed together to create unique colors.  Use on greenware, then bisque prior to applying a clear glaze.  Or use on bisque with a covering glaze applied prior to firing.   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).  When used without a glaze cover, Velvets should not be used on food or drink containers.   All are Lead free.  All are non-toxic in liquid form.  Have been tested and approved for dinnerware when covered by LG10 clear glaze.   Glazes with Zinc can cause discoloration of underglazes.  Use of Zinc-free covering glazes are recommended.
They are rich colors and can be used for all over coverage similar to an opaque underglaze.  Colors may be mixed together to create unique colors.  Use on greenware, then bisque prior to applying a clear glaze.  Or use on bisque with a covering glaze applied prior to firing.  
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).  When used without a glaze cover, Velvets should not be used on food or drink containers.   All are Lead free.  All are non-toxic in liquid form.  Have been tested and approved for dinnerware when covered by LG10 clear glaze.  
Glazes with Zinc can cause discoloration of underglazes.  Use of Zinc-free covering glazes are recommended.
VELVET CLASS PACK 12 PT ASSORTED
AMACO Velvet Underglaze 12-Pint Class Pack
Amaco Glaze Packs & Sets for Classrooms
Brilliant, ready-to-use opaque colors are approximately the same tone before and after firing May be intermixed to create hundreds of custom colors
AMACO Velvet Underglaze Pint Turquoise
Amaco Velvet Underglazes 2oz Sizes-Costa Mesa – The Pottery Studio
V-376 Hunter Green (2 oz) Amaco Velvet Under-Glaze
Amaco Velvet Underglazes – Sounding Stone
Amaco F Series Low Fire Pottery Glazes (6 Pints)
Amaco Velvet Underglaze Set - 2oz Bottles (12 Colors)
Amaco F Series Low Fire Pottery Glazes (6 Pints)