9" Dunlop Latex Mattress on boxspring or slatted bed (3" apart)?

Hi buttercupbelly,

Latex mattresses generally do best with a firm non flexing slatted foundation with a distance between the slats of no more than 3" and preferably less. There are a few exceptions generally for a thinner latex mattress where it is specifically designed to be used with a box spring (with springs that flex) and you test the specific combination.

Post #3 here and post #2 here have more information about foundations and box springs and which would generally be used under different types of mattresses.

Using a different type of foundation (flexing vs non flexing) than the one you test the mattress on can certainly change the feel and performance of the mattress.