You can apply polyurethane with a rag. Applying it with a rag is a good way to avoid paint bubbles and brush marks. Plus, it helps you paint hard-to-reach surfaces.
Earlier, most professionals preferred to apply it with a brush. But with the development of new formulations, polyurethane can now be used with a rag, or you can even spray it on the surface. Therefore, you only have to decide which way is more convenient for you.
Why Should You Use a Rag?
The main advantage of using a cloth to apply polyurethane is that you get thin coats. This means the sealant will dry faster, and you won’t deal with drips. Also, you will avoid brush marks.
Applying polyurethane with a brush has some disadvantages. For example, the brush can cause dripping and building up of bubbles, bumps, and brush marks. And, some parts of the surface are left uncovered sometimes.
On the other hand, applying it with a rag prevents drips or bubbles and provides a consistent coat with a beautiful finish. Plus, if you are dealing with hard-to-reach areas, such as vertical surfaces, it’s better to use a rag than a roller.
However, there are also a few disadvantages to using a cloth too. For instance, you will need more coats when using it. You need 8 coats of wipe-on polyurethane to get the same finish you would with 3 coats with a brush.
Types of Rags To Use
A lint-free or microfiber tack cloth is the best type of cloth to apply polyurethane. If you select a bad-quality or the wrong type of rag, such as a tint rag, you will get a bad and uneven finish.
If you don’t want to use a lint-free cloth, you can use a microfiber tack rag. They are specially made to remove dust from different surfaces, but they are also good with polyurethane since they absorb it evenly.
However, you should never use an old cloth twice to apply a sealant. After the first time, the cloth absorption power will be reduced, and that can cause an uneven finish for the next time. But, you can use an old rag that hasn’t been used to apply sealants before. Just make sure to remove the dirt before you use it.
How To Apply Polyurethane With A Rag?
Polyurethane is a top coat that can be challenging to apply. However, you can avoid common brush strokes and bubbles complaints by applying it using a cloth.
1. Prepare The Surface
You should work in a ventilated area. You can choose outdoors too but only if there is no wind or moving dust.
Before applying the sealant, you should sand the surface. Start with 120-grit coarse-grit sandpaper, and finish with 220-grit sandpaper for an unpainted surface. For painted surfaces, sand with medium or fine-grit sandpaper. After sanding, remove the dust.
2. Dip The Rag
Pour the polyurethane into a container or bucket. Avoid shaking the can before opening as it can cause air bubbles.
Take a lint-free or microfibre tack rag, dip it into the polyurethane, and wipe it on the surface in fine strokes. Apply thin layers and move the rag in a lined motion. Overlap the strokes to ensure good coverage.
3. Sand The Surface
After you cover the whole surface, leave the polyurethane to dry. It takes oil-based polyurethane 6 hours to dry for a re-coat, while water-based polyurethane takes 4 hours to dry. But, since you applied a thin coat, it will dry faster.
When the first coat dries, sand it with 320-grit sandpaper. This will help the next coat stick better. After sanding, clean the coating.
4. Apply The Second Coat
Once the first coat is dry, sanded, and clean, you can apply the second coat. Use the same technique to apply the second coat.
After you apply the second coat, wait for it to dry, sand and clean it, and apply the next one. The number of coats depends on your needs. But, 5 coats is the maximum.
You should always wait until one coat fully dries before applying the next one.
You should always wipe off the excess polyurethane to prevent paint drips. This is so important that many manufacturing companies print this instruction on the can so that users get a smooth finish.
If you don’t wipe off the excess, the polyurethane will turn sticky, and it can cause it to drip. If the sealant dries in that condition, the only way to make it correct is to sand it again. But sanding the drips can cause the removal of the whole layer if you accidentally apply pressure while sanding.
So, to avoid it, leave the sealant to dry for 30 minutes, then wipe the excess off the surface using a cloth. If the polyurethane too fast, you can dip a cloth into mineral spirits and then wipe the coating.
However, don’t leave the mineral spirits over it for too long as it can remove the whole layer.
Can You Apply Brush-on Polyurethane With a Rag?
You can apply brush-on polyurethane with a rag, but, doing so is harder. Wipe-on polyurethane is thinned with mineral spirit. Due to its thin nature, a cloth doesn’t absorb too much of it.
But, if the sealant is too thick, the rag will absorb more than the needed amount. That can lead to the finish dripping and turning sticky after it has been applied. Plus, it takes longer to dry.
So, you need to pay attention to the quantity of polyurethane the rag absorbs. So, the best way to apply brush-on polyurethane is to thin it and then use a rag to apply it.
Using a rag to apply polyurethane is doable. But, you must use a wipe-on polyurethane or thin the brush-on polyurethane with mineral spirits.
Tony is a professional painter and an author of DIY Geeks. Tony has completed over 1,000 painting projects for his clients. It's safe to say he knows what he Is talking about,