June 6, 2023

How to Properly Thin Shellac for Wood furniture

on Jan 7, 2023

While working with wood, you may want to put a finish on it. However, you’ve realized that many finishes are expensive, time-consuming, or difficult to apply to wood, so wouldn’t it be good if there was a finish that was easy to apply? This finish is shellac, and here is how you can thin it.

Shellac needs to be thinned with low water content alcohol, such as ethanol or methanol, before it is applied to wood. If using premade shellac, it will simply need to be mixed with alcohol, but if using shellac flakes, they will need to be dissolved in alcohol for several hours before use.

While shellac is quite easy to apply as a wood finish, it can take a bit to get familiar with how it works. Here are some tips and tricks to properly thinning and applying your shellac to your latest wood project.

What Are the Different Types of Shellac?

For those of you who aren’t super familiar with woodworking, you may not have heard of shellac before. Shellac is a wood finish like paint, stain, and varnish. It deepens the color of the wood and can be applied in layers and sanded like other wood finishes. It dries faster than many other finishes and is more forgiving than some of them, making it an excellent choice for a variety of woodworking projects.

However, there are some potential downsides to shellac that you may not have experienced with other types of wood finishes. Shellac does not have a long shelf life, so you need to be careful only to buy as much as you will be able to use in the near future. If you buy too much, it will likely go bad, and you will have to throw it out. Another issue is how easy it is to apply. While this is a good thing, especially for newer woodworkers, it also means that shellac isn’t the most durable wood finish.

Shellac can be removed easily with alcohol or dissolved by water. When you see white rings on old furniture, especially tables, it typically is a water ring left by a cup or plate. Shellac also cannot be used in humid places, because it will absorb the water in the air and flake off. With that in mind, there are two different types of shellac.

Shellac is made from a leftover secretion by a South Asian insect. The insect secretes chemicals to wrap their young in, and the leftover chemical gathers and hardens on tree branches. This is gathered and cleaned before being sold as shellac. If you walk into a woodworking store, they may sell these shellac flakes. Depending on how much they have been processed, they will be a variety of colors from virtually clear to a deep red. You can buy these flakes and mix your shellac yourself. You may also be able to find premade shellac sold in cans like paint or stain would be.

What Can You Use to Thin Shellac?

Whichever of these two forms of shellac you choose, you will need to thin it before it can be used on wood. Thining means that you need to “water down” the shellac to make it easier to mix and apply to the wood. However, you won’t be able to use water to thin shellac. Remember that shellac dissolves in water, which would make it unusable as a wood finish.

Instead, you will need to thin shellac with some sort of alcohol. This thins the mixture so that it can be applied with a paintbrush but allows it to keep its function as a wood finish.

Before thinning the shellac, you will need to know the cut of your desired mixture. The cut refers to how many pounds of shellac you have per gallon of alcohol. For example, a cut of 1 means there’s one pound of shellac mixed with one gallon of alcohol. Below I’ve included a chart with some simple ratios to get you started. You’ll generally want a lower cut for the beginning layers and increase the cut as you add layers to the wood.

Amount of Shellac Amount of Alcohol Cut (pounds of shellac per gallon of alcohol) 8 ounces 8 cups 1 16 ounces 8 cups 2 24 ounces 8 cups 3 32 ounces 8 cups 4

When thinning shellac, you’ll want to find alcohol with low water content. You may be tempted to use alcohol you can find around your home, like rubbing alcohol. However, most types of rubbing alcohol contain at least 20 percent water. You can use rubbing alcohol to thin shellac, but it will likely leave white marks or cloud the finish when it is applied to the wood. Instead, you’ll want to use ethanol or methanol. Be careful if you choose to use methanol since it is toxic. Only use it in a well-ventilated area and avoid letting it come into contact with your skin.

How Long Does Shellac Last?

Shellac will only last a couple of months from when it is mixed, so you need to use it fairly soon. If you buy premixed shellac at the store, the timer has already started, and that shellac has already begun to break down. Even if you thin it after buying it, you can only expect mixed shellac to last 5 to 6 months. Keep this in mind while buying shellac and only buy enough for the projects you are working on right now.

If you buy the shellac flakes, they will last much longer than premixed shellac. Keep them in a closed container where they will be kept dry and fresh. They should be stored in a cool area away from any direct sunlight. When you need to mix shellac, you can bring the container out, measure out enough for the cut that you are working with, and store the remainder. However, once the flakes are mixed with alcohol, they only have a shelf life of a couple of months like the premixed shellac.

Check out the video below to learn more about how to mix shellac with alcohol to make a wood finish.