Polyurethane is the most preferred finishing product for different surfaces, including those that have paint. We often suggest applying a coat of polyurethane over painted pieces to protect the paint and make the color pop. But, what if your surface already has high gloss paint? Can You Put Polyurethane Over High Gloss Paint?
You can apply poly over high gloss paint, provided the coat is clean and the paint cures fully. You can use either oil-based or water-based polyurethane over high gloss paint with ease but remember that the latter turns amber as it ages; hence it will alter the color of your paint. So, if what you want to achieve is a bit of extra protection for your paint, use water-based poly but if the color change isn’t an issue, go for oil-based poly because it is more durable.
Polyurethane doesn’t adhere well to glossy surfaces, so you will have to use certain products and follow a specific procedure when applying it over high gloss paint to achieve a flawless look.
How to Polyurethane Over High Gloss Paint.
Tip: If you want to apply polyurethane over a fresh coat of high gloss paint, allow the paint to cure first before proceeding.
The cure time of high gloss paint depends on whether it is oil-based or latex-based. Oil-based gloss paint will take longer to cure than latex, so make sure to check the manufacturer’s label for clear instructions. However, I recommend waiting for at least one week before applying poly over fresh high gloss paint to avoid problems.
Step 1: Clean the surface
Cleaning the surface will ensure that the polyurethane adheres firmly to the coat of paint.
- Pour some warm water in a 1-gallon bucket, then add ½ cup of Trisodium phosphate (TSP) to it to form a cleaning solution.
- Dip a clean towel into the solution, then scrub the surface to remove grease and other dirt.
- Dip another clean rag into pure water, wring out the excess, then wipe the surface to remove the cleaning chemicals.
- Let the surface dry before proceeding.
Apart from removing dirt, this cleaning action also removes some sheen from the paint, which is important for polyurethane to stick to the surface.
Step 2: Scuff the paint
- Once the surface dries, use 120-grit sandpaper or higher to etch the paint surface. Use minimum pressure because the goal is to flatten the sheen further without causing deep scratches that may show after applying polyurethane.
- You can also use a paint deglosser at this stage to flatten the paint sheen, but I recommend using sandpaper because it reduces the risk of polyurethane coat peeling in the future.
- Vacuum the surface, then use a damp rag or a tack cloth to wipe off any remaining sanding dust.
Step 3: Apply the polyurethane.
Tip: It would be best to use a brush or sprayer instead of rollers to apply polyurethane. Rollers tend to leave behind bubbles in polyurethane, and they will make your surface look unpolished once they harden into the finish.
- Apply the first coat in long straight strokes going in one direction. Ensure that you overlap each stroke with the previous one to avoid leaving streaks.
- Allow the coat to dry as specified by the manufacturer, then sand it lightly with 120-grit sandpaper or higher to flatten any bubbles present and etch the surface a bit for the second coat to stick.
- Apply a second coat of poly to ensure better protection for your painted surface.
Note: We normally recommend applying at least two coats of polyurethane over paint for extra protection. However, you can use only one coat of poly on high gloss paints because they are already tough and durable even without a protective topcoat.
Can You Clear Coat Over Gloss Paint?
Yes, you can put a clear coat on gloss paint, but it is not necessary. We normally apply a clear coat over any paint to make the paint more durable and to add some sheen to the coat. However, gloss paints are more durable than other kinds of paint, and they cure with a brilliant sheen without the help of a clear coat.
So, if your goal is to achieve a glossy look for your painted piece, I suggest using gloss paint only or starting with a flat sheen paint, then putting the clear coat to achieve some gloss.
However, if you must apply a clear coat over your gloss paint, use the following tips to avoid ruining your finish:
- Ensure that you match the brand of your clear coat to the gloss paint you used to avoid potential compatibility issues.
- Avoid using clear coats with high Volatile Organic Compounds (VOCs) in their solvents, especially on wooden surfaces. Such solvents can reach below the paint surface, emulsify wood tannins, and bring them to the top, causing the paint to “yellow” over time.
- Wait for the paint to dry first. Applying a clear coat over gloss paint before it achieves its full cure will lift the undercoat, causing a wrinkling or cracking effect.
- Avoid applying the clear coat too thick to avoid runs and sags as it dries. Also, avoid making the coats too thin because they will start to peel from the paint quickly.
Can You Prime Over High Gloss Paint?
Yes, you can. Priming is essential because it improves the adhesion of the fresh coat of paint to the old high gloss coat. I recommend using a roller to apply primer because it produces more even coats; however, if your surface has grooves or corners, use a high-quality paintbrush to navigate the grooves, then use the rollers on the flat areas of the surface.
Always apply thin, even coats of primer starting at the top of your piece, working your way down. Two coats are enough to produce a sturdy base but ensure that the first coat dries before putting on the next to avoid problems.
Additionally, it is vital to ensure that you work with a primer with the same base as your original coat of high gloss paint – if the surface has oil-based paint, you should use an oil-based primer, and the same goes for water-based high-gloss paint.
You can skip the primer if you apply high gloss over high gloss – sand the surface lightly, then apply the new paint. Furthermore, you can use self-priming paint instead because manufacturers formulate it to stick to glossy surfaces without the risk of peeling.
How Do You Strip Gloss Paint?
Gloss paint is tough and highly durable, so removing it from a surface is hard and time-consuming. Always wear a mask and gloves to protect yourself from dust, fumes, blisters, and splinters before stripping gloss paint using any of the following methods.
Chemical paint strippers are the best products to use for stubborn paints, such as gloss paint. They don’t involve much physical work, and they get the job done in a few hours. However, be cautious when using this method because some chemical strippers cause skin burns, and others may ruin the surface when left on for too long.
To remove gloss paint with chemicals:
- Shake the can with the stripping agent, then pour its contents onto a paint tray.
- Dip a paintbrush into the liquid, then coat the surface evenly to ensure that all the paint loosens evenly.
- Let the paint stripper sit on the surface as instructed on the brand label or until you see the paint bubbling.
- Next, use a plastic scraper to scrape off the loose paint lightly.
- Finally, soak a clean cloth in paint solvent to remove any remaining paint spots and residual chemical stripper.
Sanding is the best technique for removing paint, especially for small projects. Since gloss paint is tough to remove, sanding large areas would take time and energy. This method produces a lot of dust, so I don’t recommend it when stripping gloss paint indoors. However, if your surface is indoors, ensure that the workspace is well ventilated to keep dust from accumulating in the atmosphere.
To remove gloss paint with this method:
- Use a regular household cleaner or dish soap and warm water to clean the surface and dry it completely.
- Next, use coarse 80-grit sandpaper to scuff the entire surface to remove the paint. Ensure that you use minimum pressure as you sand to avoid damaging the surface.
- Use a clean tack cloth to remove sanding dust and debris, then use medium 150-grit sandpaper for the second round of sanding.
- Finish the process with fine 220-grit sandpaper to even out the surface and make it ready for the next finish you apply.
- When you finish sanding, put a little paint solvent on a clean towel, then wipe the surface to get rid of paint spots if you missed any.
Enough heat can cause layers of gloss paint to bubble and come off any surface. So you can use a heat gun as a quicker and cleaner way of stripping old paint. However, the high heat causes the paint to create harmful fumes, and if you are not careful, your surface may get scorched.
As a precaution, always keep a metal tray near you as a safe spot to put the gun down to avoid burning stuff around the workspace. Furthermore, remember to wear a respirator mask to avoid inhaling harmful fumes from the paint.
To strip gloss paint with this method:
- Let the gun heat up, then hold it at least two to three inches away from the painted surface.
- Move the gun slowly across a small area until the paint starts to wrinkle. Avoid holding the gun in one spot for too long because the paint may start producing fumes or burn your surface.
- After the coat softens enough, use light pressure to scrape it off to avoid scratching the surface below it. Try using the heat gun with one hand and scraping the paint with your other hand to develop a steady heating and scraping flow. Reheat and scrape any stubborn paint spots and use a smaller, contoured paint scraper to remove paint from narrow or detailed areas on the surface.
- Once all the paint comes off, soak a clean towel in mineral spirits, then use it to clean the entire surface.
Note: Keep a fire extinguisher on hand when using this method in case anything catches fire.
Can You Paint Over Gloss Paint Without Sanding?
You can paint over gloss paint without sanding by using a liquid sander/deglosser to remove its sheen instead.
The sheen in gloss paint makes it difficult for paint and other products to stick to it. So, we use high grit sandpaper to lightly scuff the surface to remove the sheen and promote a strong chemical bond between the old coat and the new product. Failure to remove the sheen pre-painting will cause peeling problems in the future.
However, sanding can be tiresome and time-consuming, especially when working on large surfaces like walls, and this is where the liquid deglosser comes in. A deglosser is a chemical that painters use to prepare surfaces for a coating application by removing substances that may reduce the coating adhesion.
This chemical operates by destroying the smooth finish on a surface, making it rough enough for paint and other coating fluids to grip. Furthermore, it removes the sheen from surfaces without the effort required for manual sanding, and It works in as short as 10 minutes, making it ideal for projects that you want to finish fast.
After cleaning your glossy surface with sugar soap and warm water, let it dry, then follow the steps below to degloss the old coat before applying fresh paint.
- Saturate a coarse lint-free cloth with the deglosser, then rub it on the surface in circular motions. Fold and saturate the cloth with the deglosser frequently to prevent re-depositing any dirt.
- Let the paint surface dry for about 10 minutes, then make a second application if some surface parts are still shiny.
Should I Sand Between Coats of High Gloss Paint?
You can sand in between coats of high gloss paint, but not all the time. Most brands of high gloss paint require about four hours for each coat to dry enough to accept a subsequent one. However, even though the paint may feel dry to the touch at this time, it is still soft at a molecular level. So, refrain from any form of sanding as you may smudge or cause indents in the coat.
Even though waiting a few hours between coats makes you finish your project faster, you run the risk of missing imperfections that may show on the surface once the paint dries. No matter how cautious you are when painting your piece, you may still find ridges, lint, or bubbles in your coats of paint.
So, I suggest giving each coat of high gloss paint at least 24 hours to dry before applying another one – this way; you can sand out the flaws without the risk of ruining your finish.
Always use non-clogging or stearated 220-grit sandpaper or sanding sponges when sanding between coats of high gloss paint. Sand lightly and just enough to make the surface feel smooth without removing paint in parts of the surface. After sanding, use a vacuum cleaner to remove the dust, then wipe down the surface with a damp towel to take off any remaining dust. Finally, give the surface a few minutes to dry, then apply the next coat of paint.
How Do You Paint High Gloss Without Brush Marks?
The most common problem that painters face is streaks/brush marks showing on dry coats of paint. Those brush marks tend to stand out even more in high gloss paint due to their reflective nature.
The easiest way to remove the marks and ensure a perfect finish is to sand between the coats. However, there are some changes that you can make to your painting techniques and supplies that will help you arrive at a smooth finish without sanding.
- Use a quality paintbrush.
Spending a little extra on a good-quality brush will help you achieve a cleaner finish on your piece. The highest-quality brushes are natural bristled, meaning manufacturers make them from the hairs of an animal. They are easy to work with because they easily accept paint, leave a smooth finish, and there is a low risk of the bristles falling in the paint or sticking to the surface as you work.
- Get the proper amount of product on the brush.
Sometimes DIY enthusiasts put very little paint in their brushes as a way to paint with the least amount of product possible, but it’s the wrong thing to do. Less paint on the brush is a sure way of leaving streaks on the surface because there’s not enough product to cover the surface sufficiently.
Now, this isn’t to say that you need to slather paint on the surface. If you use a lot of paint, you risk runs forming on the surface, and the paint will take longer than normal to dry.
Always make sure that the paint only touches the tip of the bristles and wipe off any excess on the side of the paint container to avoid thick layers.
- Don’t apply the paint with too much pressure.
Using too much pressure when painting a surface is a common rookie mistake. The excessive pressure will result in the paint job looking botched, plus the surface you are painting might start showing through because of uneven paint distribution.
When painting, let the tip of the brush touch the surface lightly, then move it on the surface as if you’re trying to make it float. This way, the product will stay flawlessly on the surface instead of laying too flat like a splatter.
- Use quality high gloss paint.
When working with high sheen paint, go for a high-quality brand with a long working time to achieve a smooth finish. The working time of a coating product refers to how long it will take before the top layer starts to dry. It is how much time you have to manipulate the paint by smoothing out the brush marks and edges before they harden into the finish.
If you go for cheaper products, your paint results will be less than professional, and you will have to perform repairs and retouches for a long time.
- Use a sprayer or a paint roller.
If you want to avoid the inconvenience of dealing with streaks completely, trade your paintbrush for a quality paint sprayer. Paint sprayers are easy to use, and they coat surfaces faster than paint brushes. Furthermore, spraying makes it easy to reach hidden areas of the surface without a paintbrush. The only hassle with sprayers is to ensure that you tape off all other surfaces to avoid getting paint on them, but it is worth it because the results will be flawless.
You can also utilize a roller to paint, especially on large surfaces such as walls or ceilings. However, you will need a paintbrush to cut in edges when using this method because rollers are too big to reach corners and other intricate parts.
How Do You Apply Polyurethane Without Brush Marks?
Note: for your next polyurethane project, purchase a natural bristle brush with flagged ends and a tapered profile to allow you to lay down even coats with long brush strokes.
- Start by thinning the poly by mixing it with mineral spirits in equal parts. Thinning will improve the flow-out and curing qualities of the product, which is crucial for the first coat.
- Next, brush one coat of polyurethane onto your piece holding the brush at a right-angled 10° to the surface. Apply in the direction of the grain, then when done, lightly skim the coat with the tip of the brush to help level it.
- Give the first coat 24 hours to dry, then sand it lightly with 22D-grit sandpaper. Vacuum the surface, then wipe off the excess sanding dust with a cloth dampened with mineral spirits.
- For the second coat, thin the polyurethane again but make it 25% mineral spirits and 75% polyurethane. Use the same brush technique as the first coat, then allow it to dry. Sand, the second coat with 320-grit sandpaper, then apply two more coats of unthinned poly sanding between each.
- Finally, allow the finish to cure for one week, then use 600-grit silicon carbide sandpaper to level the surface. You can sand again with finer sandpaper or rubbing compounds to give the polyurethane coat a flawless glossier look.
How Do You Remove Brush Strokes From Polyurethane?
Worry not if you still see brush marks on your polyurethane finish even after utilizing all the proper application techniques. You can remedy the flaws by sanding them without ruining your piece or having to remove the finish. Afterward, apply a light coat of poly to disguise the sanded area. Below is a step by step guide on how to do it:
Step 1: Sanding
Start by sanding down the brush streaks lightly with the fine 220-grit or 300-grit sandpaper. Ensure that you apply even pressure to the area to avoid sanding down some areas more than others.
Step 2: Remove the dust
Next, use a soft cloth to wipe the sanded area and remove all traces of grit and dirt from the surface. Ensure that you wipe the surface properly because if any particles remain, they will get caught under the new layer and ruin the finish again.
Step 3: Apply the new coat.
- Dip a paintbrush lightly into the polyurethane and make sure to wipe off any excess product on the side of the container. Doing this will ensure that you don’t put too much finish on the area you want to coat. Furthermore, it is better to apply several light coats to achieve the desired look than to apply too much and risk streaks or bubbles in the finish. Apply the poly in long gentle brush strokes, overlapping each of them to avoid leaving streaks again.
Step 4: Let it dry
Let the polyurethane dry for a full day, then inspect the dried spot for brush marks. If some remain, repeat all the steps above until you achieve the perfect finish.
Many reasons lead painters to put polyurethane over paint. Most of the time, it involves adding some sheen to dull finishes or protecting the paint from cracks, dings, and damages caused by moisture.
High Gloss paint by itself cures into a shiny and durable coat that easily resists damage even without the help of a clear topcoat. You want to make the paint even more durable, or you may be attempting to reduce its sheen by adding a clear coat with lesser gloss to it. But,
Can You Put Polyurethane Over High Gloss Paint?
You can apply polyurethane over high gloss paint, provided you remove the sheen, making it difficult for coating products to adhere. You can remove the sheen by sanding the coat with fine-grit sandpaper or by using a deglosser if you’re working on a surface that is too large to sand.
Furthermore, it is best to let the paint cure first if you want to polyurethane over a fresh coat. This way, you minimize the probability of the paint bleeding into the clear finish or smudging in some areas.