As mentioned earlier, yellow nails could be caused by several things, including some medical conditions. When it comes to nail polish, though, the yellowing is a result of your nails absorbing some of the pigment from the polish. Shades of red, from light pink to dark burgundy, make up the widest variety of nail polish colors in the United States, and the darkest reds are most likely to stain your nails yellow.
Let's look closer at one family of these pigments, iron oxides. This includes some of the same chemicals we refer to as "rust" when they occur naturally on cars and old metal pipes. Paint manufacturers, including some nail polish makers, often use iron oxides as red and yellow pigments.
If you've spent much time in an older home, you know that water running from old iron pipes can be brown from rust, and a porous porcelain sink connected to those pipes takes on brownish red stains from the iron oxides in the water. Iron oxides in nail polish are suspended in a much different solution. Because the keratin in your nails can absorb liquid, the nails can also absorb the iron oxides from your polish just like that porcelain sink absorbed them from the water. As a result, your nails may have a yellowish or brownish stain for a while even after you remove the coats of polish.
Can a base coat help? The primary reason to apply a clear base coat to your nail first is to form an even surface for applying the color polish. Some base coats are substantial enough they serve as the complete first layer of polish. In some cases, these could cut back or eliminate the yellowing that could result from contact between the nail and the pigment.
Can nail polish remover be a problem? The remover itself can be volatile and could damage the skin with too much exposure, but it's not likely to cause yellowing of the nail on its own. As a strong solvent for the polish, though, it could increase the exposure of your nail to the pigment in the polish. Reduce this exposure by frequently changing to a new cotton ball or other applicator while you're removing the polish.
For more information about nail polish and nail care, put on your coat and head over to the next page.