Wood stain and wood varnish are both important pieces of the wood finishing process. But what’s the difference between them?
Wood stain soaks into the wood, and is intended to change the color of the wood. It doesn’t offer any protection. Comparably, wood varnish is a protective coating that sits on top of wood, and acts as a barrier against water and dirt. Often times, woodworkers will use both products when finishing a piece.
There’s a bit more nuance than that, though, so lets go deeper!
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Wood Stain Vs Varnish: The Primary Differences
The main difference between wood stain and varnish is the purpose – wood stain colors the wood, varnish protects it.
Wood stain offers very little protection, since it is a very thin liquid that works by soaking into the wood pores. Any excess wood stain is wiped up before it dries.* Because of this, wood stain is applied first in the finishing process, otherwise the varnish would prevent the stain from reaching the wood pores.
Varnish, on the other hand, is a clear barrier that offers protection to the wood. It usually doesn’t significantly change the color of the wood, although oil-based varnishes usually “warm” the wood up a little bit (aka, add a warmer tint.)
Varnishes can also add a sheen to the wood – you usually can pick a “glossy,” “satin” or “flat” varnish. Because wood stain soaks into the wood and doesn’t sit on top, it doesn’t have this option.
Outside of that, it’s a bit difficult to compare, because “wood stain” and “wood varnish” are both huge categories that contain a variety of different products, each which have different features and application methods.
For example, there exists oil-based wood stain, water-based wood stain, and gel stain, each which work completely differently, and have different rules for application. For more about these, check out this post on staining wood.
Wood varnish is technically a narrower category, which basically consists of brushing varnish and wiping varnish. But if by “varnish” you really mean “wood finish,” then we’re talking about polyurethane, oils, water-based finishes, shellac, lacquer, and waxes.
As you expect, they all work completely differently, apply differently, and have different rules, which you can read all about in this post on choosing a finish.
*Note – Wood stain never really dries. It just turns sticky. If you’re about to use wood stain for the first time, make sure you wipe up any excess before it dries, otherwise you’ll have a giant mess to clean up before you can apply finish.
Using Stains and Varnishes
As we’ve discussed above, wood stain is intended to color the wood, while varnish is intended to protect the wood. Because of this, woodworkers frequently use both wood stain and varnish on a single piece.
However, there are a couple rules to mixing and matching stains and varnishes. Not every stain and varnish play nicely with each other.
First off – if you’re using a water-based stain, use a water based finish. If you’re using an oil-based stain, use an oil-based finish.
While wood stains aren’t suppose to affect the adherence of wood finish, sometimes they do, especially if they haven’t had enough time to fully dry.
This is much less likely to happen if you use wood stains and finishes that are the same type of product, aka, both water-based, or both oil-based.
If you absolutely need to mix and match, I recommend apply a coat of Zinsser’s Shellac Sealcoat between the stain and finish. This seals the stain in the wood, and you should be able to apply your wood finish with no problems.
Combo Stain/Varnish Products
I know what you’re thinking next – are there any products out there that both stain and protect? Yes.
Varathane’s Poly+Stain, and Minwax’s Polyshades are both combo stain/varnish products, which claim to stain and protect the wood one go.
Technically, they’re more like tinted varnishes, since the product doesn’t actually soak into the wood, but instead applies a colored varnish on top of the wood.
This has a similar effect to staining, in that the wood looks a different color, even if that color hasn’t actually soaked into the wood pores.
Theoretically, these products are great. You don’t have to worry about adhesion problems caused by the stain, you don’t have to apply quite as many layers of product, and poly/stain products can even be applied on top of former finishes, since the “stain” doesn’t need to reach the wood pores to work.
But I’ve never had a good experience with them. One time, Polyshades didn’t dry right. Another time, despite 5 minutes of stirring, the stain wasn’t evenly dispersed, and I ended up with a chalky finish the second half of the can.
After the third attempt, I gave up and switched back to applying stain and finish separately.
Obviously, feel free to give them a shot. But I’ve found them to be more trouble than they’re worth.