Polyurethane is used as the final coat of a paint job. But does this mean you can’t stain over polyurethane? Here is the answer to that.
You can stain over polyurethane. Though polyurethane is commonly used as a sealant, you can still apply stain over polyurethane but only when the polyurethane is completely dry.
Also, you can’t use regular stains over polyurethane. This is because regular stains need to penetrate and polyurethane is a hard and moisture-resistant layer that will not allow regular stains to penetrate.
To stain over polyurethane, you can only use a topical stain like gel stain. Topical stains don’t need to penetrate so these stains can easily stay on the polyurethane coating.
But that’s not all. There is more to know about staining over polyurethane. For instance, does stain stick to polyurethane? Let’s find out.
- 1 Does Stain Stick To Polyurethane?
- 2 Is It Necessary To Apply Stain After Polyurethane?
- 3 How Does Polyurethane Affect Stain Color?
- 4 How To Stain Over Polyurethane? (Made Easy)
- 5 What Types Of Stain Can You Apply Over Polyurethane?
- 6 How Long Does Polyurethane Take To Dry Before Staining?
- 7 How Long Should I Leave A Gel Stain To Dry On Top Of Polyurethane?
Does Stain Stick To Polyurethane?
Regular stains don’t stick to polyurethane. But topical stains stick properly to polyurethane. Here is why:
Stains are not designed the same way as paints. When you apply paint over a surface, the paint doesn’t need to penetrate the surface because the paint coating will stick to the top layer of the surface. Stains however have a different design.
For stains to stick, the stain coating needs to penetrate and soak into the material. This is why stains are commonly used on porous materials like wood where the stain can easily penetrate.
The need to penetrate creates a problem for stains when you apply them on polyurethane. Polyurethane when dry forms a thick and hard layer that doesn’t allow anything to penetrate. So when you apply regular stain over polyurethane, the stain will not be able to penetrate the polyurethane.
Since the stain needs to penetrate to stick, the stain will not stick to the polyurethane and will become sticky after a few hours. This is why it’s usually advised to remove the polyurethane coating with a paint stripper before painting over it.
However, this is not the case for all stains. While regular stains need to penetrate, topical stains usually referred to as sealing stains don’t need to penetrate. Topical stains like gel are designed the same way as paints. These stains don’t need to penetrate to stick. Since these stains can stick without penetrating the material, they will work well over polyurethane.
So in summary, only topical stains will stick to polyurethane. For regular stains to stick, you have to remove the hard polyurethane layer.
But is it necessary to apply stain after polyurethane? Let’s find out.
Is It Necessary To Apply Stain After Polyurethane?
It’s not necessary to apply stain after polyurethane. Polyurethane is designed to be used as a sealant or top coat. This means that the paint isn’t designed to be painted or stained over.
Also, being a sealant, polyurethane is very hard and durable which means it doesn’t need a protective layer over it. So it’s not necessary to apply stain after polyurethane.
However, you can apply stain over polyurethane if you’ll like additional protection. Though polyurethane is as strong as any paint or sealant, you can put a coat or two of gel stain over the polyurethane for improved durability and protection.
You can also apply stain over polyurethane if you’ll like to tint the polyurethane finish. Polyurethane is a clear sealant meaning that it doesn’t have any color or pigment. But if you’ll like to add color to the polyurethane finish, you can put a few coats of stain over the polyurethane.
However, ensure to use only a topical stain over the polyurethane. Oil-based gel stains come in different colors so you have a wide range to choose from.
How Does Polyurethane Affect Stain Color?
Polyurethane makes stain appear lighter but this only goes for water-based polyurethane. When you put water-based polyurethane over stain, the polyurethane coating makes the stain color appear lighter than it is. This is why water-based polyurethane is commonly used to lighten dark wood stains.
The reason for this is that water-based polyurethane allows light to reflect through the finish to the stain. Since water-based polyurethane is a clear sealant, light easily reflects through the polyurethane. This makes the stain underneath appear lighter or brighter.
Oil-based polyurethane on the other hand makes stain color appear yellowish after a while. This is because of the high oil content in the oil-based polyurethane.
Since the polyurethane is dissolved in oil, it’s not as clear as water-based polyurethane that is dissolved in water. So if you put oil-based polyurethane over stain, it will affect the color of the stain by giving it a yellowish tint after a few days.
Now, let’s check out how to stain over polyurethane.
How To Stain Over Polyurethane? (Made Easy)
Putting stain over polyurethane can be a bit daunting if you don’t know the right steps but this guide will show you how to do this in 5 simple steps.
First, you should remember that you can only apply a topical stain over polyurethane. Regular water-based or oil-based stains will not stick unless you remove the polyurethane first.
So for this guide, we’ll be applying gel stain over polyurethane. You can also put Miniwax Polyshades over polyurethane. Miniwax designed the paint to be used on rough surfaces like polyurethane. To put stain over polyurethane, you’ll need a few tools and supplies:
- The stain preferably a can of gel stain
- Foam brush or a regular paintbrush
- Fine-grit sandpaper
- Orbital or palm sander (for large surfaces)
- White vinegar or white spirits
- Painter’s tape (optional)
- A pair of gloves and breathing protection
Here is a guide on how to apply stain over polyurethane:
1. Degrease The Polyurethane
You need to clean the polyurethane coating to remove grease and oils that may repel the stain and prevent good adhesion. Since you are using a topical stain that will stay on the polyurethane, oils, and grease will also cause bleed through in the finish so it’s important to decrease.
If you are want to apply regular stain over polyurethane, now is the time to remove the polyurethane. You can do this using a paint stripper.
To do this, you can use a degreaser, white spirits, white vinegar, or rubbing alcohol. Don’t use too much of any of these solvents or you’ll ruin the polyurethane. Simply dampen a clean rag with any of these and use the damp rag to wipe the polyurethane. After, let the polyurethane dry.
2. Sand The Polyurethane
The next step is to sand or scuff the polyurethane finish. To do this, you are to use fine-grit sandpaper. 320-grit works nice.
You don’t have to scrub or abrade the polyurethane. You are using fine sandpaper to smoothen the polyurethane and make it ready to absorb the stain.
After sanding, ensure to vacuum dust from the surface. You can also use a cloth to wipe the polyurethane finish. Since you are applying a topical stain, you don’t need to prime the polyurethane.
3. Apply The Gel Stain
The next step is to put the gel stain over the polyurethane. You can do this using a foam brush. But some painters also use a regular paintbrush or a rag.
Ensure to use whichever method you are comfortable with. You only need 2-3 coats of the gel stain for proper coverage over the polyurethane. If you want a really dark shade for the finish, you can apply up to 5 coats of gel stain.
4. Wipe The Excess Gel Stain
Ensure to wipe off the excess gel stain from the finish with a clean rag. This is to prevent the stain from getting tacky or sticky. You should do this quickly while the stain is easier to wipe.
What Types Of Stain Can You Apply Over Polyurethane?
The only type of stain you can apply over polyurethane is a topical stain. This means stains that don’t penetrate the material to stick or dry properly.
Regular stains will have to penetrate the polyurethane surface to perform well and since the polyurethane is hard and impenetrable, regular stains will not stick well.
The only type of stain that can stay on polyurethane are those that don’t need to penetrate to stick. These are topical stains. The best option is gel stain.
How Long Does Polyurethane Take To Dry Before Staining?
You should let the polyurethane cure completely before staining. On average, this will take 3 days. Water-based polyurethane cures in less than 48 hours.
So you can apply stain over water-based polyurethane in about 2 days. Oil-based polyurethane dries slower than water-based polyurethane so you should let the polyurethane dry for at least 3 days before staining over it.
If you stain over polyurethane too soon, the finish will not dry well because there will still be moisture in the polyurethane coating. Also, the polyurethane coat will not be hard or strong enough to support the topical stain. This will ruin the entire finish.
How Long Should I Leave A Gel Stain To Dry On Top Of Polyurethane?
You should leave the gel stain to dry on top of the polyurethane for at least 24 hours. This is to give the gel stain enough time to dry and harden.
Leave each coat of the gel stain to dry for at least 8 hours between coats. You should leave the gel stain to dry and cure for at least 3 days before moving furniture or objects on it. If you don’t abide by these times, the finish will be affected.
Overall, you can apply stain over polyurethane but you should only apply a topical gel stain on the polyurethane. Regular stains won’t stay on the polyurethane because they can’t penetrate.
Only topical stains will work since they don’t have to penetrate or soak into the material to stick. If you’ll like to apply regular stain over polyurethane, you have to remove the polyurethane first.