A quick tutorial video showing how to set up an Adobe Illustrator file for printing with HP Latex white ink.
Steps:
0:31 Window/Layers
0:59 Duplicate your artwork layer
1:14 Rename the duplicated layer if desired (I usually call it "White Artwork")
1:42 Turn off visibility of the artwork layer
2:43 Select all in the white layer
2:44 Object/Expand - make sure Fill and Stroke are both selected
3:25 Set a fill color - make it contrast with your artwork
3:57 Window/Swatches
4:07 Add new swatch from the Swatches palette
4:16 Name: Spot1 for Onyx; White for Caldera
4:37 Color Type: Spot Color
5:04 Window/Pathfinder
5:24 Unite filter in the Pathfinder palette (this is optional)
7:35 Turn artwork layer visibility back on
7:38 View/Overprint Preview
7:43 Window/Attributes
7:48 Overprint Fill on in Attributes palette
It's usually harder to read these steps than it is to actually do them - give it a shot and tell me what you think!