Polyurethane is a clear sealer that produces a moisture-resistant layer and protects the surface underneath. But, can you apply it with a rag?
You can apply polyurethane to get thin coats and prevent drips, brush marks, and bubbles. You must use a lint-free or microfiber cloth to apply it.
Why Should You Use A Rag To Apply Polyurethane?
You should use a rag to apply polyurethane to get thin coats, prevent drips, brush marks, or bubbles, and help the sealer dry faster. A rag will also help you to apply polyurethane in hard-to-reach areas, such as a vertical surface.
But, you need more coats when using a cloth. You need 8 coats of wipe-on polyurethane to get the same finish you would with 3 coats with a brush.
On the other hand, applying polyurethane with a brush has some disadvantages too. 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.
What Type Of Rag Do You Need For Polyurethane?
You need to use a lint-free or microfiber tack cloth to apply polyurethane. The wrong type or a bad-quality rag, such as a tint rag, will produce a bad and uneven finish.
If you don’t want to use a lint-free cloth, 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.
Never use the same old cloth twice to apply polyurethane. After the first time, the absorption rate of the cloth will be heavily reduced, and this can produce an uneven finish for the next time.
However, you can use old cloths that haven’t been used to apply a sealer before. Just make sure to clean the dirt or dust before you use it.
How To Apply Polyurethane With A Rag?
To apply polyurethane with a rag, do the following.
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 24 hours to dry for a re-coat, while water-based polyurethane takes 6-8 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.
Do You Wipe Off Excess Polyurethane?
You must always wipe off the excess polyurethane to prevent drips on the finish. This is such an important tip that many manufacturing companies print this instruction on the can so that users can see it.
The polyurethane will turn sticky, and tacky, and will drip off the surface if you don’t wipe off the excess. If the sealer dries in that condition, you must sand the drips off the surface.
You can accidentally remove the whole layer while trying to sand off the dried drips from the surface. So, leave the sealer to dry for 30 minutes and then wipe off the excess from the surface using a cloth.
If the polyurethane dries too fast, dip a cloth into mineral spirits and wipe the coating. After 5 minutes, remove the mineral spirits from the finish as it can remove the layer.
Can You Apply Brush-on Polyurethane With a Rag?
You can apply brush-on polyurethane with a rag, but doing so is harder. The brush-on polyurethane must be thin enough so the rag doesn’t absorb too much of it.
Wipe-on polyurethane is thinned with mineral spirits to prevent the cloth from absorbing too much of it. If the sealer is too thick, the cloth will absorb too much, leading to an uneven and dripping finish after it has been applied.
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.