Excellent! *rushes off to try a new deed*
Well just tried it and thanks very much Tazar. For anyone else wondering, seems you can use a furniture dye tub or natural dye on the deed, and as Tazar stated, once you place the display case you're stuck with that colour. You can tell if a deed has been used because after you axe the case you get a deed that is oriented differently than an "unused" display case deed.