Texture is the complaint that most often sends people to the primer aisle, and it is worth separating into its components, because they are not all the same problem and they do not all respond to the same thing. Pores are open shadows. Fine lines are channels. Crepiness is a fine, loose network of very shallow lines in thin skin. Bumpy or rough surface is usually dryness or dead surface cells. Only the first three respond to blurring at all, and the fourth responds to exfoliation and moisture.
What a blurring primer physically contains is silicone elastomers — soft, springy silicone particles that sit on the surface and scatter light in multiple directions rather than letting it bounce off cleanly. Scattered light produces fewer and softer shadows, so the dips in an uneven surface read as less distinct. It is the same optical principle as a diffuser on a camera flash.
The reason this is a targeted product rather than a face product comes down to film thickness. Elastomer primers are the heaviest primers on the market by feel, and a heavy film across your whole face means your foundation is sitting on top of a thick layer rather than on skin. Two films crack along a crease more readily than one, which is why a blurring primer applied everywhere can leave you worse off than no primer at all on exactly the lines you were trying to soften.
Where this product shines is one area: a textured nose and inner cheek, or a patch of crepiness on the upper cheek. Applied there, thin, patted rather than rubbed, and given a minute to set before a thin foundation goes over it, the effect is genuinely visible — and it is the one thing in a makeup bag that does anything at all about surface texture.
