Rectified tile is a term that is applied to specialty ceramics and porcelains. What does it mean? Does rectification make for a better tile?
What It Is
Rectified tile is fired tile — ceramic or porcelain tile — that has been mechanically cut or ground down to an exact size. Since it applies only to the tile's edges, it is called an edge treatment. Additionally, the edges are usually precisely cut at a square: a 90-degree angle. Rectification is not considered better than other edge treatments; it is just a different treatment that allows for a different look.
How to Find It
All major tile manufacturers carry rectified tile. For example, the pictured 12" by 24" Neutra (Leather) from Eleganza is a rectified tile. You usually need to look at the specifications and edge finish, to determine if a tile is rectified.
Rectification Controls Tile Shrinkage
If you have ever baked a pizza, bread, or cookies, you know that it is impossible to predict the eventual size of the product. With heat, it first expands, then it contracts as it cools. While ceramic and porcelain clays do have more predictability than dough, they still are subject to size variability based on minute differences in firing temperatures and composition of materials: tile shrinks upon firing. So, ordinary tiles that are molded and then fired, but not rectified, will have slight dimensional differences that may affect how neatly and precisely the tiles are laid out. It is important to note that rectifying effects only the tile's facial dimensions, meaning the side-to-side sizing you see when looking down at a tile. It will not correct the thickness of the tile.
You may want to buy rectified tile if any of the conditions apply:
1. You Want Thin Grout Lines: 1/8"
According to online tile retailer South Cypress, "The main point in purchasing a rectified product would be for minimal grout joints."
The thicker the grout line, the more tolerance you have available to accommodate oddly sized tiles.
Notice that quarry tiles — those thick, often red, and unrectified tiles you see outdoors — may have lines as thick as 1/2" to cover for imperfect facial dimensions.
2. You Want to Lay Larger-Sized Tiles: 15"-16" and Above
It is rare to find small rectified tile. Just how small is the minimum, though?
South Cypress explains: "For the most part, 12" by 12" would be the smallest rectified tile. We have several mosaics that are 1" by 1" or 2" by 2" and are cut (and therefore technically rectified), but they are mesh mounted and the grout joint is predetermined."
3. You Want a Clean, Precise Grout Line
The clean, 90-degree angle afforded by the tile-cutting saw means that your grout line would be equally clean. For materials like honed, polished tiles that readily show errors, rectification is a necessity. It's important to make certain that your substrate is absolutely flat when laying large rectified tile. You do not have the surface tolerances with larger tile that you might with 4" by 4", 2" by 2", or certainly mosaic tile. Lippage will be immediately apparent when laying tile with thin grout lines.
4. You Want Fired Tile, Not Natural Stone
Rectified applies only to fired tile. You do not find the term applied to marble, granite, or travertine. Since these are natural stones, they are, by definition, already rectified since they need to be cut from larger blocks of stone.