Ions, being charged particles, dissolve quite readily in water and interact with it more closely than do oils, such as may be found in tea. It's for that reason that the change in texture produced by the kettle is different from one that tea could produce (less gloopy, more viscous), but for other reasons that are beyond me, the particular changes my tetsubin produces work together with certain teas to create a greater seamless whole.
The second thing I notice is a metallic, sweet taste. It's faint and fleeting, but it's there. After swallowing the water, the initial texture remains, but distilled. There's no longer a solution of ions swishing over my tongue, but the particles that happened upon my palette and stayed there continue to create a feeling of substance. I'm tempted to describe the water as having a slightly earthy and lengthy aftertaste, but the use of these qualifiers would be inaccurate as there is, in fact, no taste.
In all, the result is much more like a liquified canvas than any stone fruit or mineral water. With a thick textured and tight weave, the water has substance without conveying any particular artistic intent or message. Not entirely impartial, robust paints and thick brush strokes as well as careful but strong detailing will be lent added impact, while pale watercolours will all be muted as they soak into the fabric. An often overlooked part of any painting, without its texture a reproduction will never have the same depth of character as the original. With the right tea and a skillful brewer, this kettle can truly create a work of art.