Can You Stain Over Polyurethane

Can You Stain Over Polyurethane?

Although wood is usually stained before polyurethane is applied, you may find yourself in a situation where you want to stain over polyurethane. But is this even possible?

The answer is YES, but there are some important things you need to know before you start staining polyurethane.

In this post, I’ll explain if you can stain over polyurethane, the steps on how to do it, and a few tips and tricks to get the look you want. Let’s dig in!

  • Gel stain is really the only wood stain that can be applied directly to polyurethane. Other stains don’t adhere to poly well, mainly because these stains are designed to be absorbed by wood pores.
  • However, you can use water-based wood stain if the polyurethane is water-based, mainly because the stain and poly contain many of the same components, so they mix quite nicely.

Can You Stain Over Polyurethane?

Yes, you can stain over polyurethane, provided you use the right stain on the right polyurethane.

Specifically, you need to use a gel stain. These stains are virtually the only ones you can use to stain poly; other stains won’t adhere to a polyurethane surface properly.

The only exception, however, are water-based stains, but these only work with water-based polys.

But choosing the right stain isn’t it; you have to make sure it’s applied properly, otherwise you could get a blotchy surface, and nobody wants that!

To make the poly surface ready for stain, you should do some light-scuff sanding with some fine-grit sandpaper or fine steel wool.

Light sanding will reveal the layers of poly that haven’t been exposed to the air, moisture, etc., and these layers will be able to receive and hold stain, unlike the fully cured top layer.

After the surface has been sufficiently scuffed, you can apply the gel stain. Be careful not to use too much, otherwise you could have a mess on your hands later on.

It takes a coat of gel stain six to eight hours to dry. You should apply two to three coats of stain, especially if you’re using a lighter stain.

Can You Stain Over Polyurethane Without Sanding?

Staining Wood Over Poly

No, you shouldn’t stain polyurethane without sanding first. Well, you can, but you won’t get the results you’re looking for.

A polyurethane surface needs to be scuffed up before stain is applied, otherwise the stain won’t be able to set in the poly.

Once polyurethane is completely cured—and this takes anywhere from 14 to 30 days (depending on the poly you use)—it becomes unstainable.

That’s because the top coat is completely solid. Even a gel stain, which hardens on top of wood and not in its pores, won’t adhere to a smooth layer of polyurethane.

You don’t need to rigorously sand for the surface to be stainable; light sanding with fine-grit sandpaper will do.

Essentially, you’re just trying to scratch the surface. You want to avoid taking too much poly off, otherwise you’ll expose bare wood, and if this gets stained along with the poly it’s likely a blotchy surface will be the end result.

How to Stain Over Polyurethane

Applying gel stain to polyurethane isn’t the easiest staining task, but once you get the hang of things you’ll find that applying stain over polyurethane isn’t all that different from applying standard wood stains.

1. Gather Materials

Before you start roughing up a polyurethane surface, you’ll need to get all your materials together. Here’s what you’ll need:

  • Gel wood stain
  • Safety gear (gloves, a respirator & goggles)
  • A few microfiber cloths
  • A tarp
  • A sponge
  • Sanding paper or steel wool

If you’re looking for a gel stain for wood, I highly recommend this Varathane gel stain.

Varathane 349560 Premium Gel Stain, Half Pint, Dark Walnut
  • Designed for vertical surfaces including doors, window trim and furniture; creates a natural wood…
  • Formulated with a thicker consistency to prevent drips and runs and provides twice the coverage of…
  • Dries to touch in 1 hour and covers up to 60 sq. ft. per half pint; allow 2 hours between coats

It’s best to gather everything you need before you start working, as this way you don’t have to stop midst working to get something at the store.

Ensure you have all necessary safety gear, such as a respirator, gloves, and eye protection. Also, make sure all your skin is covered, as wood stain can irritate the skin (unless you use a natural wood stain).

Once you have all your materials, you’ll need to prep your work area.

Be sure to only apply stain in an area that has good ventilation to limit your exposure to VOCs.

Both wood stain and polyurethane are rife with volatile organic compounds (VOC), especially oil-based products, and if you’re exposed to these for a prolonged period your health may be adversely affected in a variety of ways.

To boost air circulation, run a couple fans, ideally a ceiling fan and a floor fan.

2. Prep the Surface

Sand the Wood Surface

When you have all your materials and your workspace is ready, you can begin the staining process.

First, you’ll need to clean your workpiece. You can use mineral spirits (paint thinner) or denatured alcohol to clean the polyurethane topcoat.

Cleaning will remove dirt and other erosive elements that can negatively affect drying wood stain.

Cleaning before staining is also imperative if you want to ensure the final wood stain color is visually appealing.

For oil-based polyurethane, use mineral spirits for cleaning; if it’s a water-based polyurethane you can go with denatured alcohol, as this isn’t quite as strong.

If you apply an excessive amount of either cleaning solution, you can wear down both surfaces too much, so it’s best to be conservative when applying cleaning solution.

3. Sand the Surface

Once your workpiece has been thoroughly cleaned from top to bottom, it’s time to start sanding; this is arguably the most important part of the process, so take your time.

You should sand lightly to avoid making obvious sanding marks. Polyurethane that’s been lightly sanded won’t feel noticeably scuffed, and sanding shouldn’t generate a ton of sanding dust.

So if you’re eventually standing in a cloud of dust and the surface feels rough, you’ve sanded too much and you’ll have to fix up the poly before applying stain.

Note: Some woodworkers recommend using a sanding sponge at this point, but I’ve found that fine-grit sandpaper does the trick. A sanding sponge helps to avoid sanding marks, but a dark enough stain can eliminate these too.

4. Apply the Stain

completed diy wedding centerpiece box cedar fence pickets stained medium brown rustic

After the polyurethane has been adequately roughed up, it’s time to apply the gel stain. Remember, you need to be conservative when applying gel stain, as applying too much will just create a mess later on.

You can apply this with a natural bristle brush, a foam roller, or a sprayer (if the stain has been thinned for spraying).

Personally, I like using a foam brush because it combines the best of what natural bristle brushes and foam rollers have to offer.

I don’t use a spray gun because I don’t like thinning stain; I’ve found that thinning stain usually lightens the color of it.

Apply the stain evenly and wipe down any areas that have been oversaturated with stain. Once you have an even coat, wait five to seven hours for the gel stain to dry.

5. Repeat Steps 1-4 for Each Coat

Once the base coat has dried, assess it.You can run your hand over the stain to ensure it’s smooth.

When you’re satisfied with the results, repeat steps one through four for each new coat of wood stain.

If you’re using a darker gel stain, you’ll probably only need two to three coats; a lighter stain will probably require four to five coats.

And when it’s time to sand the existing stain, you need to be careful. If you sand with too much pressure, you may sand off all the stain you just applied, in which case you’ll have to re-stain before you can apply a new layer.

Note: Don’t think you can cut any corners just because you’ve already applied a layer of stain. All it takes is one improperly applied layer to mess up a multi-coat finish.

6. Seal the Finish

When you’ve reached the desired number of coatings, it’s time to seal the stain. I recommend sealing with a spray-on, water-based poly. This will form a thin and discrete yet protective layer.

Water-based polys are colorless, unlike oil-based polys, so you won’t have to worry about it discoloring the stain you just applied.

Sometimes I’ll spray water-based poly because it doesn’t need to be thinned before spraying. Also, it’s easy to apply an even finish when spraying this poly.

If you need some help, check out the video below!

Tips for Staining Over Polyurethane

Use Dark Wood Stain

If you’ve taken the unconventional route of staining over polyurethane, I recommend using a darker stain over a lighter one.

A lighter shade of stain rarely goes well with existing poly, especially if the poly is old. When the stain dries, it’ll look faded and discolored. This doesn’t happen with darker gel stains because they more or less overpower the shade of old poly.

But when you apply a darker wood stain, you should apply thin layers only. If you apply gel stain in thick coats, you’ll be left with a lot of excess gel stain, and this residual material will need to be removed with a clean rag right away, otherwise the poly won’t stain evenly.

Don’t Sand All the Polyurethane Off

You may be tempted to sand off all the existing polyurethane to reveal the wood surface underneath, but you should avoid doing this.

Since polyurethane has already been used, the wood’s pores will not be able to accept additional stain. That’s because the first polyurethane coat has filled the wood pores.

This is why—if you’re going to stain and use polyurethane—you need to apply wood stain before you apply polyurethane.

Also, attempting to remove all the polyurethane finish from a wooden surface could result in you damaging the wood, and if this happens it’ll be hard to achieve a visually appealing and overall smooth surface.

So remember to lightly sand with sandpaper and a sanding block; steel wool works too.

But whatever you do—don’t reach for any kind of power sander!

Don’t Apply Too Much Stain

When you apply gel stain over polyurethane, you need to apply thin coats only. This way you avoid having a lot of residual stain after the base coat dries.

It’s easy to inadvertently apply gel stain in thick layers because of its consistency, which is why you need to pay extra attention to ensure this doesn’t happen.

If you believe you’ve applied too much stain, you can go over the surface with a clean rag to remove the excess stain. Just make sure you’re careful when removing stain, as applying too much pressure could result in an uneven coat.

And don’t use a damp rag to remove residual stain, as the moisture could discolor the stain, especially if it’s darker.

If you apply too much stain, you’ll soon realize that excess stain peels and chips off, sometimes taking sections of the base coat with it, revealing the wood grain.

Make Sure the Polyurethane Can Accept the Stain

Just like with wooden surfaces, you need to rough up a polyurethane surface first so it can accept stain.

Even though polyurethane doesn’t have pores, the layers under the fully cured topcoat can accept stain, as these haven’t been hardened by air and moisture yet.

To expose the inner layers of a poly surface, you only need sandpaper or steel wool.

If you reach for a power sander instead, you’ll probably take off too much polyurethane in some sections, and if you stain the poly in this condition it won’t just be uneven but blotchy too—and nobody wants that!

What Stain Goes Over Polyurethane?

Use a Gel Stain

Gel stain is a lot like other wood stains, but its ability to dry above the wood’s surface is what separates it from the more traditional wood stains.

Both water- and oil-based wood stain need to seep into wood’s pores before they can set. If the wood’s pores are blocked, these stains won’t hold, and they’ll eventually dry up and peel off.

What’s interesting about gel stain is that a thin layer can accentuate the wood’s unique features just like regular stain, even though it’s applied above the surface. Compare this with paint, which also sits atop a surface but changes the way that surface feels.

Applying gel stain is really no different than applying regular wood stains—just lightly sand, apply, wait, and repeat.

If you don’t have a gel stain, the Varathane stain below is my favorite.

Varathane 349560 Premium Gel Stain, Half Pint, Dark Walnut
  • Designed for vertical surfaces including doors, window trim and furniture; creates a natural wood…
  • Formulated with a thicker consistency to prevent drips and runs and provides twice the coverage of…
  • Dries to touch in 1 hour and covers up to 60 sq. ft. per half pint; allow 2 hours between coats

Water-Based Wood Stain With Water-Based Poly

If the existing polyurethane is water-based, you can apply water-based stain over it. You can only do this with water-based stain because the components are similar. Oil-based stain wouldn’t set right, in large part because oil-based stains are too thick, even when applied in thin layers.

One attractive thing about this poly-stain combo is the staining process is a lot faster. It’ll take 6-7 hours for multiple coats of poly to dry, and then a couple layers of stain should be dry a few hours later.

Of course, if you want a darker shade, the process will take longer, for you’ll need to apply more coats, no matter what kind of wood stain you’re using.

Final Thoughts

So, can you stain over polyurethane? The short answer is yes!

In the end, there are two ways to stain over polyurethane:

  • The first way is to use a gel stain, as this stain works best with polyurethane.
  • The other way is to use a water-based stain, but this only works if you’re applying water-based stain to a water-based poly.

While it’s possible to stain poly after it’s been applied, most woodworkers stain wood first. After they know the stain has come out well, they apply polyurethane.

Not only does stained wood look better than stained polyurethane, but stain that’s under polyurethane is protected, whereas stain that’s above it is not.