The most common use for finish nails are to attach trim and molding to a house. The reason for using these types of nails are for the fact that they can be sunk into the trim or molding. This leaves a hole to be filled in with putty to make the trim or molding smooth. A finish nail is small and has small heads. They range in length from 1 to 4 inches. For finish nails, just like any other nails, weight is determined by what is called "pennyweight". You can also get different gauge sizes since nails are made from steel wire. 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 has been around for many years. It comes from England and means the amount that was paid for 100 nails. If it cost 5 pennies for 100 nails than people started calling them 5 penny nails. This way of determining the weight of a nail has suck around and is still used today. People in earlier years took the symbol "d" from the Roman word denarius which means the same a penny. The way to show a nails 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 length of a finish nail is important. The width of the trim or molding determines the length of your finish nail. If the width of your wood is half inch than the nail should have a length of one and half inches. All you are doing is making your nail 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 head of the nail is just a little bigger than the shaft of the nail. In the top of the head of a finish nail is a small spot to place the point of another nail so you can tap the finish nail into the wood. This is called sinking the nail. After you get all you nails sunk then you go back and fill the holes with putty. Though finish nails are made to sink into the wood, it isn’t always needed. You can just tap the nail flush with your wood. A good example for doing this is if you can get the same color nail as your trim.
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.