I like to explain glazing this way. Imagine a paper receipt that is perfectly white, that’s fallen on the floor of an auto mechanic’s garage. When that piece of paper first falls on the floor it is very opaque and white. It stands out and actually sits on top of the floor. It’s noticeable, appears to “come forward” compared to the oily, dirty floor. But gradually, as the week goes on and the mechanics walk on top of it with their dirty boots, and oil and grease, this begins to stain and discolor the white paper receipt. In fact, by the end of the week the accumulated dirt and grease (the glazes) will have made the receipt almost disappear on the floor, as it will blend in. The receipt, because of all this staining, will have moved “back in space” visually to the same level as the floor.
Glazing makes opaque surfaces have the look and feel of transparency and generally speaking, transparency goes back in space. Opaque colors tend to come forward in relation to transparent colors because they don’t have anything on top of them. They are clean and solid just like that paper receipt when it was first dropped on the mechanic’s floor.