ok I'm making up a batch of flavour specific juices for my various can mods from sincitymods.com and was wondering what colourings can you add to e-juice safely and will not harm equipmen. In particular my Romulan Ale can I want a berry tasting juice with a blue colour to it. Any help would be appreciated as I'm assuming food colours would be safe to ingest but are they in VPs??
TIA
TIA