Wood stain is a common item on the shelf of most woodworking shops, and most woodworkers, hobbyists, or otherwise, will use wood stain. Coloring the wood to the desired hue for your workpiece will be achieved by using wood stain, but this may result in some additional queries about what you can do after using stain. For example, can you varnish over stain to protect the wood?
You can varnish over stain, but you need to match the wood stain with the type of finish that you want to use on your wood. Oil-based stains must be used with oil-based polyurethane varnishes, while water-based stains can only be used with polycrylic varnishes, which are also water-based.
Wood stain, in most cases, is used to tint the wood to the desired color, but it is not considered a finish that is applied to the wood. The reason we say in most cases is that there are some products where this is an exception. The type of finish you put on the wood will start with your choice of stain. So, what are the best ways to finish the wood after you have stained it, and would varnish be an appropriate finish?
The huge variety of finishes for furniture is one of the subjects we will be diving deeply into during our live online workshops at Cucamonga Woodworking and you can check out our past workshop YouTube videos Here(Link to Cucamonga Woodworking)
Can You Use A Varnish Over A Wood Stain?
When you start a woodworking project, you will need to plan out the project from start to finish. Many people forget about the stain and the finish, and it is just slapped onto the project as an afterthought, and they use whatever product they have in their garage at the time.
Wood stain and the finish that will go over the top of it will essentially determine the project’s final look and how well your work turns out. It is a good idea, for this reason, to include the stain and the finish on the wood in the planning stage of your project.
When you are planning your stain and finish, there are some choices that you need to factor in that will determine the type of finish that you need on the wood, and the type of finish will dictate the type of stain you can use on the wood.
The Difference Between Varnish And Stain
A wood stain is not intended to be a sealant that protects the wood from the elements and gives the project a durable finish. Instead, wood stain is intended to color the wood to make the wood take on a different appearance from its natural colors.
A varnish or a sealer is intended to be a top protective coating for the wood that will protect it from the elements and wear and tear during use. Thus, a wood finish such as varnish is always required as a top-coat over a stain to provide that protective, durable finish for the wood.
But what varnish can you use over a stain, and are there differences in the stains available that would require the use of a different finish?
Types Of Wood Stain
There are essentially two main types of wood stain, and each is intended for specific purposes and to be used with particular finishes. This means that your choice of finish should be the primary driving factor in your choice of stain.
The two main types of stains available are water-based stain and oil-based stain, which we will examine to determine their properties so you can make the right choice for your project.
Water-based Wood Stain
Water-based wood stains are becoming more popular because of the benefits they offer over oil-based stains. They are more environmentally friendly, use less harmful and toxic chemicals, make them healthier to use, and post-job cleanup is easier with soap and water.
Water-based wood stains are intended for indoor use. Water-based stains will dry faster than oil-based stains and, thus, make the project take less time.
Oil-based Wood Stain
Oil-based stains require ventilation when you apply them because of the harsh-smelling, volatile chemicals in the stain. Oil-based stains are more durable and protect the wood better, which means they can be used for indoor projects as well as outdoor projects.
The post-job cleanup is messier with oil-based stains and requires the use of additional solvents. The oil-based stains also take longer to dry and increase the time the project will take to complete.
Where Will Your Woodwork Project Be Used?
The biggest determining factor that will drive your choice of finish on the wood will be the location where the finished project will be used.
Is it a project destined to be used exclusively indoors, or is it a piece that will be used outdoors and exposed to sun, wind, and moisture elements regularly?
These questions need to be answered as part of your planning of the project, and the answer to this question will influence your choice of the final finish. Therefore, the type of stain that is used will need to be appropriate to the type of finish required by whether the piece will be indoors or outdoors.
Thus, the type of finish should determine the choice of stain-type and not the other way around. This means that in the planning stage of your project, you would need to answer the following questions in the following sequence to make the right choice of stain and varnish.
- Where will my project be used, indoors or outdoors?
- What will be the appropriate varnish to finish the project for the intended location?
- What is the best stain to use with the selected varnish to finish the project?
Types of Varnish To Use Over Stain
As with wood stains, there are essentially two types of wood varnishes, polycrylic and polyurethane, and you need to use the appropriate stain with each of these varnish types.
Polycrylic Varnish
Polycrylic varnish is a water-based varnish that is becoming a popular choice for preserving wood and putting a finish of wood projects intended for indoor use. Polycrylic, is in fact, only suitable for finishing indoor use projects.
If you finish your woodwork project with polycrylic and it stands outdoors, it will offer no protection to the wood from the elements, and the finish will quickly blister, crack and flake off the wood when exposed to direct sunlight.
However, when the project is kept indoors, where it will be protected from the elements, polycrylic is often the finish of choice. There are some characteristics of polycrylic that make it a good choice for indoor use.
- Polycrylic is less toxic than other varnishes.
- It does not have strong, pungent fumes.
- The fumes are not flammable.
- Polycrylic dries faster and is easier to apply.
- For indoor use, the finish is durable
- Only suitable for indoor use.
- Cleaning tools like brushes and rollers is easy with soap and water.
What Stain To Use With A Polycrylic Varnish
If your project calls for a polycrylic finish, this will affect the type of stain that will be the corresponding choice for this finish.
You should not pair an oil-based wood stain with a water-based finish such as polycrylic. Therefore, if you intend to use a polycrylic finish, you must select a water-based stain to get the desired color on your wood before applying the finish.
Polyurethane Varnish
In contrast to polycrylic, polyurethane is an oil-based finish which makes it a suitable choice for either indoor or outdoor use, but this choice will affect the stain you choose, which will have to be one that is compatible with the varnish.
Polyurethane provides a much more durable finish to the wood, and it offers the wood a greater degree of protection from the elements than polycrylic does.
For this reason, if your project is an outdoor one, the only choice would be a polyurethane finish. If your project is an indoor project, you have the choice of going with a polyurethane finish or with a polycrylic finish, depending on your preference.
Polyurethane has a strong, pungent smell to it, with fumes that can be both volatile and toxic. When working with polyurethane, you should work in a well-ventilated area and also use breathing protection while applying this varnish.
Here are the main characteristics of polyethylene varnish, which may help you with your finish selection.
- Polyurethane is not environmentally friendly.
- It has very strong pungent fumes that can linger for a while on the project.
- The fumes can be toxic and flammable.
- Polyurethane dries slower and is more difficult to apply.
- The finish is extremely durable, more so than polycrylic.
- Only suitable for indoor and outdoor use.
- Polyurethane is the only choice for an outdoor project.
- Cleaning tools is difficult, requiring additional time and chemicals such as mineral spirits or thinners.
What Stain To Use With A Polyurethane Varnish
Since you should not use a water-based wood stain and apply an oil-based finish over the top, you will be restricted to using an oil-based wood stain if you intend to finish the project with a polyurethane varnish.
Pairing the right stain with the right varnish will provide the best finish for your piece and offer the wood the best protection.
Can You Mix Oil-based And Water-based Stains And Finishes?
In some instances, you may have no other choice but to use a water-based varnish over an oil-based stain or the opposite, where you need to use an oil-based finish over a water-based stain. Is this an option, or will it ruin your project completely?
While it is possible to apply an oil-based varnish over a water-based stain and vice versa, it is not often done because of the additional time the project would take.
If you need to apply a varnish over a wood stain that it is not appropriate for, you need to give the stain a drying time of at least 72 hours before applying the varnish.
If you are using a water-based stain and you want to put an oil-based varnish over it, if the stain is not completely dry, the oil-based varnish will trap moisture from the water-based stain inside the wood, which would promote the growth of mold inside the wood.
With an oil-based stain, the oil needs to have sufficient time to soak into the wood; otherwise, the water-based finish will not be able to penetrate deeply into the wood, and it will rather just sit on top of the oil-based stain.
This extended drying time for the stain, should you want to use a non-compatible varnish over it, is often what makes the mixture of these two types of products undesirable.
It is for this reason that it would be better to stick to using an oil-based stain with an oil-based varnish and a water-based stain with a water-based varnish.
What About Gel Stains?
A relatively new product out on the market is gel stains. These stains are a mixture between paint and a stain. They add color tones to the wood that are similar to paint but still allow the grain and texture of the wood to show through. They offer an almost translucent finish to the surface of the wood.
Gel stains are becoming popular because they are easy to apply, and they create a different finish to the wood than other stain types. These stains, however, do not penetrate deeply into the wood but rather coat the surface of the wood, where they harden when they dry and create a surface layer that looks similar to varnish.
A gel stain is not a sealant, and as such, it would still need to be covered with an appropriate varnish to seal and protect the wood.
Gel stains have polyurethane incorporated into their make-up and would therefore be better paired with an oil-based polyurethane varnish as an appropriate finish over this type of stain.
Summary Of Varnishing Over Wood Stain
As a quick reference summary, we have put together this table of the different types of varnish and stains. This will give you an easier visual representation of which stains to pair with which types of varnish.
| Polycrylic VarnishWater-based | Polyurethane VarnishOil-based | |
| Ease Of Application | Easy to apply, but you need to work quickly due to the fast drying time | Harder to apply evenly, but you can take your time to cover the entire project |
| Drying Time | 1 to 2 hours | 12 to 24 hours |
| Durability | Many coats (about 5 or 6) to get good durability. | Good durability with just 2 coats of the varnish |
| Location Suitability | Indoors | Indoors and Outdoors |
| Environment | Better for the environment and less toxic fumes when applying. It should still be applied in a well-ventilated area. | Toxic, pungent, and flammable fumes require the use of a mask as well as plying in a well-ventilated area. The smell lingers on the wood for a while. |
| Clean-up | Easy with soap and water | Requires paint thinner or mineral spirits |
| Compatible Wood Stain | Water-based | Oil-based |
Conclusion
The conclusion that we can draw from this is that if you want to get a great finish on your project instead of a mediocre one, you need to factor your wood stain and your wood finish into the planning phase of your project.
If you intend to use a polyurethane finish on your wood, which can be for an indoor or an outdoor application, then the best stain to used would be an oil-based stain.
If your project is intended for indoor use only, you have the choice of opting for a polycrylic varnish as the finish for the wood. In this case, the appropriate wood stain to choose would be a water-based stain that would be a better match for the water-based varnish.
While you can mix these two different product types and use a water-based stain with an oil-based varnish and vice versa, you would need to leave at least a 72-hour drying window for the wood stain before you would be able to apply the varnish coats over the top of the stain.
However, this drying time is often impractical to get a project completed over the space of a weekend for a home woodworker or get the job out in time for a customer in a professional woodworking shop.