Finish nails can sink into the trim or molding, leaving a hole to be filled in with putty to make the trim or molding smooth. A finishing nail is small and has small heads. They range in length from 1 to 4 inches. For finish nails, weight is determined by pennyweight. You can also get different gauge sizes. These types of nails are most commonly used for interior finish work; however, they can be used outside. Most finish nails are shot from a nail gun, using an air compressor to drive it into the trim.
The term pennyweight comes from England and means the amount that was paid for 100 nails. If it cost 5 pennies for 100 nails then people started calling them 5 penny nails. This way of determining the weight of a nail has stuck around and is still used today. The way to show a nail's pennyweight is as follows: 2d, 3d, 4d and so on. Finish nails range from 2d to 20d in pennyweight. Determining the penny size nail you need is easy: you take the length of the nail and subtract a half inch. Once you have that number you need to multiply by 4. This will give you the penny size.
The width of your project determines the length of the finish nail you will need. Make sure your nail is three times the width of the wood. Since finishing nails are used in the finish work there is usually no need for a very long nail. You can still get them from a length range of one to four inches.
Finish nails are made to sink into the wood and leave a small hole. The top of the nail is just barely bigger than the shaft of the nail. On the top a finish nail is a small spot to place the point of another nail so you can tap the finish nail into the wood. Though finishing nails are made to sink into the wood, it isn’t always needed. You can just tap the nail flush with your wood.
Since finish nails are made of steel you can get different gauge sizes. This determines the hardness of the nail. Finish nails range in gauge from 16 to 10. The smaller the gauge the harder the nail.