Doing the arithmetic
A twelve inch sheet of one inch chips holds a hundred and forty four pieces. The same sheet in two inch chips holds thirty six.
Count the lines between them and the one inch grid has eleven joints running each way against five for the two inch. That is roughly twice the length of joint in the same area, and joint is a material with its own color and its own texture, so doubling it changes the surface rather than just the pattern.
Why that matters more than it sounds
On a large format tile the joint is a thin line at the edge of the field of vision. On a one inch mosaic it is a grid running through everything you look at.
Which means the joint color is not a finishing decision on this page, it is half the design. A joint matched to the chips gives one continuous textured surface; a contrasting joint turns the sheet into a drawn grid and the chips into squares inside it.
The square is the original mosaic
Every other mosaic shape, the hexagon, the herringbone, the arabesque, the basket weave, is a departure from this one.
A small square grid is what Roman and Byzantine floor mosaic was made of, and it is still the format that carries the most materials, because a square is the easiest shape to cut from anything. The stones, glasses and fired bodies in this range all arrive in it.
Where the small square earns its place
A surface that is not flat. A shower pan, a curved wall, a step, a niche with three internal corners, a bench: anywhere a large piece would have to be cut apart to follow a shape.
The smaller the chip the tighter the curve it can follow, which is the practical reason a one inch sheet exists alongside a two inch one. Mosaic tile is the full range, other shapes and other materials alike.
The materials and finishes here
Glass, marble, porcelain and other stones run through this range, on glossy, polished, matte, tumbled, textured and anti-slip faces.
White and multicolor lead the colors, then beige and gray. A multicolor square sheet is worth noting: with a shape this plain, a blend of tones is the only variation available, which is why blended sheets concentrate in the small square formats.
What a plain grid asks of the room
A square grid has no direction and no figure, so it does nothing to a room on its own. That is either the point or the problem, depending on the surface.
On a shower pan it is exactly right, since the floor of a shower is not supposed to be a feature and the grid quietly does the geometric work. On a wall the same sheet needs something else to carry it, which is why square mosaic walls are almost always either strongly colored, blended across several tones or glossy enough to do something with the light.
Sheets and thickness
The sheet size is 12x12 through most of the range, with 12x18, 12 5/8x12 5/8 and a 10 5/8 inch square, at 3/8 inch for most of it and thinner for the glass.
A 12x12 sheet covering a square foot is the tidiest relationship in mosaic, and the square grid is the reason: it is the one pattern that divides into a foot without a remainder.
