Coffin nails, also called ballerina nails, are a nail shape that tapers along the side walls and ends in a flat, squared-off tip, which needs real length and a strong nail plate or an extension to wear well.
Also known as: ballerina nails, coffin shaped nails, coffin nail shape, short coffin nails
A coffin nail is a stiletto with the point cut off. The sides taper inward from the base, then the tip is filed flat, so the outline looks like a coffin or the toe of a ballet shoe. The two names describe the same shape. The look needs length: on a short nail there is no room for the taper, and the result reads as a plain square.
Mavala lists coffin among the shapes that need length and strength and that break most, alongside almond and stiletto (Mavala). Filing the side walls removes the part of the plate that resists bending, and the flat tip has two corners that catch on fabric. For that reason coffin nails are usually worn on gel polish, acrylic or press-on tips, which add stiffness a natural nail of that length rarely has.
To file a coffin on a long natural nail, start with a square. Angle the file against each side wall and stroke toward the tip in one direction, keeping the two slopes equal. Then file the tip straight across and lightly bevel the corners so they do not snag. Check the width of the flat tip on every nail so the set matches.
Coffin nails give a long, flat canvas, which is why they appear in nail art and in chrome, cat-eye and French designs. A shorter coffin, sometimes called a short ballerina, keeps the tapered outline on medium length with less breakage. Whatever the length, cap the free edge with each coat of polish and reapply top coat every 2 to 3 days (Manucurist).