I've seen Craft White used to coat a chipboard shape, and once it's dry you can go over it with one or more of the classic colours and get a much better finish than if you had coloured with Classic ink directly onto the chipboard. Be careful though, the white takes longer to dry than you might expect.
(for any non Aus/NZ demos reading this - the only Craft ink we get here is white, so our substitute for Craft colours is to ink the stamp with Versamark and then with a classic colour, stamp and emboss with clear powder. Just in case you're wondering why I'm suggesting using Craft as a base for Classic colours). We keep asking for Craft colours but so far no joy.
Another thought - have you tried the white Staz On from the spring mini? You may have to reink the pad each time you use it, but it does give a good effect. It's a challenge to get off your stamps though, so get the Staz On cleaner as well. (looking on the bright side, that's an upsell opportunity
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