Need to finish some furniture at home? It's a good idea to seal the wood before painting it, as you can appreciate the natural beauty of the material. In order for this beauty to last for years to come, you will need to prepare the surface with sandpaper first. Among the sealants available on the market, there are three main types: polyurethane, shellac and lacquer. Each of them requires a different method of application. In this article you will learn how to seal and prepare wood for painting. Get to work!
Steps
Method 1 of 4: Smoothing and staining the surface
Step 1. Sand the wood until it is very smooth
With a hand or electric sandpaper, sand the surface of the material to remove imperfections. If the wood is too rough, start with coarser sandpaper, 100 or 120 grit. As you ungross the wood, progress to finer grains. At the end of this step you will be using 400 grit sandpaper. The surface will be smooth!
- Even if the surface already looks quite smooth, run 400 grit sandpaper over it before proceeding. The sealant needs to be applied to the completely smooth surface.
- Sand the wood in the same direction as its grain, that is, following the lines of the material. This way you avoid leaving tracks on the wood.
Warning:
Wear a protective mask to avoid breathing wood particles during the process.
Step 2. Remove any remaining dust from the surface of the wood
With a dry cloth, wipe the surface of the material several times. This way you prevent wood particles from sticking to the sealant, which would result in an imperfect surface.
- The tack cloth, also known as dust catch, is made especially for these cases. It removes dust left after the sanding process. Some particles will resist if you use a common dish towel, for example.
- Do not splash water on unsealed wood as the liquid can penetrate the material and coarse the grain.
Step 3. If desired, dye the wood to highlight or change the grain color
Apply the stain before the sealant so it can penetrate the material. There are different types and colors of sealants available on the market, but most can be applied with cloths. First, you'll apply it to the wood and let it work. As for the time of action, read the instructions left by the manufacturer on the product label. Then wipe off the excess with a clean, dry cloth.
- The stain's packaging informs you of the proper waiting time between stain and sealant.
- You can find stains and sealants in any home and building store.
Step 4. If you want to save time, use a product with stain and sealant together
It is possible to waterproof and color the surface of the wood at the same time. In some cases, this combination of the two will be helpful.
- Many people use this combination of sealant and stain on very large, time-consuming decks.
- You can find the product in any home and building store.
- Apply the products using a brush or roller.
Method 2 of 4: Sealing with Polyurethane
Step 1. Choose a polyurethane that fits the design
There are different types of polyurethane: oil-based, water-based and other synthetic blends Each of the types have different characteristics. It all depends on what you are going to seal and how it will be handled in the future.
- Oil-based polyurethane is more resistant to the elements of the weather, but takes much longer to dry and cure than water-based products. These, on the other hand, dry and cure faster, but last less if exposed to inclement weather.
- When choosing the product, you will also need to choose between glossy and matte finishes.
Tip:
Polyurethane is great for waterproofing wood. In addition to being easy to apply, it lasts a lot and beautifies the surface of the wood. However, be aware that the product will create a glossy or matte layer, actually changing the appearance of the material.
Step 2. Apply polyurethane on wood with a brush or cloth.
Place the wood on a surface where polyurethane can fall. With a brush or cloth, apply the product to the surface of the material with gentle movements.
- Because it is thin, polyurethane is self-levelling, that is, it spreads on its own on the surface of the wood. No need to be concerned if the product will be unevenly spread.
- Use a little more polyurethane on the cut and exposed edges of the wood, as it is more vulnerable to water penetration there.
Step 3. Apply a thin layer over the entire surface
Using long strokes, use a brush or clean cloth to spread the polyurethane. Spread it from side to side, always trying to maintain an even distribution of the product over the wood.
- The best way to apply polyurethane is using a cloth.
- Wear gloves during the procedure to prevent the product from coming into contact with your hands.
Step 4. Sand the surface of the wood between one layer of polyurethane and another
With 400 grit sandpaper, sand the entire surface of the material to eliminate imperfections. In this step, do not apply too much force to the sandpaper. Take it easy.
Before sanding the surface, wipe it with a cloth to remove any traces of wood
Step 5. Apply multiple coats of polyurethane to make the wood look as it should look
Apply several layers of polyurethane, always waiting for the drying time between one hand and the other of the product.
- Keep an eye out as the brush may drip drops of polyurethane after application. If that works, smooth them out.
- Drying time varies. Therefore, carefully read the manufacturer's instructions on the product packaging. Also pay attention to the temperature and humidity of the environment.
Method 3 of 4: Sealing the Wood with Shellac
Step 1. If you are sealing wood that will not be exposed to the outside climate, use shellac
Shellac is a great sealant to apply to furniture, for example. Although not waterproof, it gives a beautiful finish and prevents furniture from drying out over time. Therefore, you can use it to seal wooden shelves, racks and cabinets.
Shellac is sold in several colors, giving the wood shine and color at the same time
Step 2. Use a sponge, brush or clean cloth to apply shellac
You find all of these materials at home and construction stores. Don't buy expensive sponges and rags, as you'll throw them away when you finish the job.
- Use a sponge or cloth if you need to cover large surfaces.
- If you need to penetrate the shellac into cracks and corners that are harder to reach, use a brush. It will be useful for sealing pieces of wood with details.
Step 3. Apply shellac straight across the entire surface
Using a sponge, cloth or brush, apply the shellac in long strokes. Ideally, the applicator object is well soaked with the product.
- Start at one end of the wood and cross quickly to the other side, leaving one trail to dry before passing the other. Work methodically and quickly.
- Shellac is not the easiest sealant to apply as it dries very quickly.
Step 4. Don't touch shellac while it dries
After application, do not touch the product; let it dry. After application, do not sand the surface.
Shellac self-integrates into each subsequent layer, giving the wood a smooth, smooth finish
Tip:
If you don't like shellac and want a different finish, you can apply polyurethane or lacquer over it, as long as you wait for it to dry first.
Method 4 of 4: Applying Lacquer to Wood
Step 1. Only use lacquer if you have some experience applying other sealants
Lacquer is a very resistant high performance finish applied with a spray gun. When dry, the product leaves the surface of the wood very hard. Because of all this, lacquer is not for amateurs and does not forgive errors in application.
The spray gun costs between R$100.00 and R$200.00. Without it, it is not possible to apply lacquer
Step 2. Take all necessary safety precautions to apply the lacquer
Keep the area ventilated and keep the gun away from any sparks. It is absolutely necessary to take all protective measures when dealing with lacquer.
When inhaled, lacquer is extremely toxic. Keeping the environment well ventilated and wearing a breathing mask is essential
Warning: If using a fan, make sure it does not produce any sparks first.
Step 3. Apply the lacquer in thin layers
With the spray gun, apply very thin layers of lacquer. Bring the pistol closer to the wood, press the trigger and move it over the surface. Each time you go back and forth, overlap about 50% of the previously lacquered area. Release the trigger shortly after coming off the wood. Make quick movements in a straight line until you cover the entire piece with lacquer.
Keep the gun always in motion so that no lacquer builds up anywhere on the wood. This way you avoid droplets and uneven areas
Step 4. Apply three or four coats of lacquer in total
Wait for the product to dry completely before applying other hands. The wood will take about 30 minutes to dry. At the end of this time, apply the next coat using the same method described above, never stopping the gun in the same place.
After receiving all the necessary layers, the wood will be sealed, smooth and resistant
Tips
- Regardless of the type of sealant used, use light movements. It's more a matter of manners than strength.
- Fill all the wood grains with the product to ensure that water will not penetrate the wood in the future.