Understanding Wood Stains & Finishes

Types of Wood Stains & Finishes

A wood stain is a material, typically a liquid but sometimes a gel, that is applied to a substrate to change its color. In this article, the substrate in reference will be wood. The color of the stain is due to either a dye or pigment that's either solvated or suspended within the liquid, often referred to as the vehicle. The stain (vehicle and colorant) then penetrates the wood, and as it dries or cures, the colorant adheres to the wooden fibers.

There are several different types of wood stain that are often used. Specific stains have certain properties and are selected based on desired outcome and type of wood. The different wood stains include:

• Oil-based stains
• Water-based stains
• Water/Bio-based stains
• Gel stains
• Stains

Oil-Based Wood Stains

Oil stains are often linseed oil–based. Oil-based stains are considered the easiest to work with because they take a long time to dry, which provides a more even coat. Additionally, the longer drying times help the stain penetrate the wood and provide a more rich color.

The general advantages of oil-based stain are:

• Easiest to work with
• Typically leaves a richer color
• Provides a more even coat

In contrast, some of the disadvantages of oil-based stains are:

• Noxious chemicals are used as the vehicle and require a well-ventilated work area or respirator mask.
• Removal of an existing finish is necessary before applying an oil-based wood stain.
• They require solvents to clean up.

Water-Based Stains

The binder or vehicle that water-based stains use is water. This provides faster drying times and easier cleanup compared to oil-based stains. Water-based stains usually absorb into the grain quicker but tend to raise the grain. This may necessitate sanding between successive coats. A brush or a rag can be used to apply water-based stains, but since the stain is thinner, a brush may be the easier way to apply it. Faster drying times may also mean uneven coloring if care is not taken.

Some advantages to using water-based stains are:

• Environmentally friendly when compared to oil-based stains
• Highly resistant to mold
• Quicker application of multiple coats due to faster drying times
• Easier to achieve softer colors
• Soap and water cleanup

However, some disadvantages include:

• They are more difficult to use on larger projects due to fast drying time.
• The water-based stains tend to lift the grain in the wood.
• Any existing wood finish needs to be removed before application of water-based stains.
• Achieving darker colors requires multiple applications of the stain.

Water/Bio-Based Stains

The binder or vehicle is water and a plant based oil. This is not to be confused with a plant based oil stain or alkyd chemistry. For sake of this article, we wanted to focus on a hybrid water based chemistry that balances the best of both worlds. Converting the plant based oil to a water phase material provides faster drying times and easier cleanup compared to oil-based stains. A water/bio-based stains usually absorbs into the grain quicker and deeper but may raise the grain depending on the wood species or sanding finish level. A brush, stain pad, or a rag can be used to apply water/bio-based stains, but you must be sure to rub in the stain without leaving topical material.

Some advantages to using water/bio-based stains are:

• Environmentally friendly when compared to oil-based stains
• Virtually odorless and non-flammable compared to oil-based stains
• Highly resistant to mold
• Quicker application of multiple coats due to faster drying times
• Easier to achieve softer colors
• Achieve a more natural looking stain without hiding the wood grain
• Soap and water cleanup

However, some disadvantages include:

• Any existing wood finish needs to be removed before application of water/bio-based stains.
• Achieving darker colors requires multiple applications of the stain.

Gel stains

Gel stains are different from either water-based or oil-based stains. The gel stain tends to behave somewhere between a stain and paint. This results in a messier application process, whereby it is best to use rags or clothes to help spread the stain. While little preparation is needed when using gel stains, cleanup does require the use of mineral spirits.

There are some advantages of using gel stains:

• Less preparation when compared to water-based and oil-based stains
• Help hide blotching due to varying densities and resin within the wood
• Adhere well even if the previous finish is not completely removed
• Provide an even coloring to the wood

Gel stains are different from water- and oil-based stains and therefore have some different disadvantages:

• Cleanup requires mineral spirits.
• They are overall messier than water-based or oil-based stains.

Finishes

After staining wood, it is best to protect it with a finish. Finishing wood will help it resist scratches, protect against water and reduce discoloration due to sun bleaching. There are several types of wood finishes or varnishes, which are discussed in more detail here. Varnishes generally protect the wood and stain as a top coat but also can penetrate the wood as well.

Polyurethane

Polyurethanes can be either water based, oil based, or a hybrid water/bio-based. In a similar fashion to stains, water-based polyurethanes dry fast whereas oil-based polyurethanes take much longer. In general, water-based polyurethanes:

• Dry quickly
• Provide a clear and colorless finish
• Some protect hardwood floors, based on their formulation

Oil-based polyurethanes are similar, but tend to be different from water-based polyurethanes:

• Dry more slowly
• Dry with an amber hue
• Tend to be a good choice for protecting hardwood floors

Lacquer

Lacquers are thin liquids that make a clear and high-gloss finish. Lacquers can be sprayed on and dry rapidly, making the few coats that are necessary quick to apply. This finish is not suitable for outdoor use, though.

Other Finishes

There are other finishes, such as simple oil, waxes or shellac. These finishes are applied by rubbing the material on the wood. Waxes do not penetrate but simply create a top protective layer. While these are all effective in protecting woods, polyurethanes and lacquers are more often used as finishes.

Summary

Generally, a stain is applied with either a brush, stain pad, or rag, penetrates the wood grain and leaves the wood a different color than it was. A topcoat then protects the wood and color that has been applied. Eco Safety Products offers nontoxic stains and sealers from its EcoProCote line that utilize water/bio-based chemistry to provide high-quality color and finish to your wood project.

Oil- vs. Water-Based Stain vs Water/Bio-based Stain

Water-based stains are easier to work with than oil-based stains but are not ideal for large projects due to their fast drying time. Oil-based stains tend to penetrate the wood deeper, resulting in less-long term maintenance, and tend to provide a more even and durable stain. A water/bio-based stain balances the attributes of water and oil based chemistry with the only potential drawback is the possibility of slight grain raising depending on the wood density.

(Finish) Varnish vs. Stain

Stains provide the colorant to the wood project, whereas varnishes provide a protective topcoat. Staining is normally a two-step process in which the stain is applied in one or more layers, and then a varnish is applied in one or more layers to protect. Sometimes varnish can have a color on its own, which should be recognized before application.