These papers are also unsuitable for photographic work because standard office paper is usually not "white" enough. This results in a poor color gamut and leads to "muddy" colors. For all types of paper, printer driver settings must be adjusted to suit the paper, so that the printer delivers the right amount of ink. Photo paper is inkjet paper specifically for printing photographs. It is a bright white due to bleaching or pigments such as titanium dioxide, and has been coated with a highly absorbent material that limits diffusion of the ink. Highly refined clay is a common coating to prevent ink spread. The best of these papers, with suitable pigment-based ink systems, can match or exceed the image quality and longevity of photographic gelatin-based silver halide continuous tone printing methods used for color photographs, such as Fuji CrystalArchive (for color prints from negatives) and Cibachrome/Ilfochrome (for color prints from positive transparencies). For printing monochrome photographs, some photographers believe that traditional silver-based papers exhibit deeper black tones and smoother tonal gradation compared with inkjet prints; however, objective testing of contemporary fine art inkjet media (in particular the finer gloss and luster papers) does not support these impressions. Paper is one amongst several key elements determining the quality of the print; the others are the ink, the printer, the printer/paper profile, the software used for print preparation and most importantly - the skill and expertise of the print-maker. Photo paper is typically divided into "glossy", "matte", "semi-matte", "semi-gloss", "satin" or "silk", and "matte" finishes. Paper thickness varies widely. Lighter weights are not much different from the general-purpose office papers described above, and can be used for all types of printing, though these are the least expensive and lowest-quality photo papers. Photo papers for more critical work are thicker and have advanced coatings, sometimes with quick-drying properties. They can normally be printed only on the one specially coated side. A few papers are coated for double-sided printing. Glossy photo paper has a shiny finish that gives photos a vivid look. It is generally smooth to the touch and has some glare depending on the lighting and the angle at which it is viewed. Matte photo paper is less shiny. Matte and glossy prints typically feel different to the touch, and they have different photographic properties. Black density and gamut of matte papers is normally less than for gloss or luster papers because of less reflectance and greater absorption/spread of ink into the paper.