PU Polish or polyurethane polish is a type of hard malleable polymer used as a protective coating that can be applied on wood, metal surfaces, or other furnishing items. It comes in a translucent liquid form (not completely transparent), in which the base surface of the product is visible. It protects the surface against moisture, scratches, dust, water, and harsh UV rays whilst still retaining a pleasant appearance. PU polishes are available in solvent-based and water-based forms and both these types come in a variety of finishes, ranging from matte to glossy. Water-based polish is more environment friendly while solvent-based PU finishes are a more established form of finish. It is also available in multiple stains that can be picked according to the desired shade of wood. PU polishes are odorless, have quick drying, and have low maintenance, creating a protective layer with excellent resistive properties.
Main Features of PU Polish
Durability- PU Polish is a tough synthetic polymer that laminates surfaces by forming a transparent coat on top of the surface. It has high resistance to solvent degradation and is used on surfaces that require abrasion resistance, fast curing, adhesion, and chemical resistance such as bowling alleys. The curing time for standard PU polish is around seven days. This polish is more durable against harmful UV rays of the sun and this radiation is absorbed to a great extent by the PU coating and protects the surface from substantial damage. With good maintenance, PU-polished furniture can last more than 15 years.
Safety– PU polish is relatively safer with petroleum-based solvents and has fewer volatile compounds in water-based polishes. Volatile organic compounds are not present in 2-part PU polish. Individuals doing the coating process must wear proper PPE, including gloves, caps, and masks covering their eyes, nose, mouth, and hair.
Disadvantages– The fumes generated while applying solvent-based PU polish need to be cleared out of the area hence it’s important to work in a well-ventilated space. This polish could also give a slight yellowish hue to the wood finish on the extremely light-colored wood surface and the PU finish can also darken over time.
Cost- The price of the polish can be different depending on the brands and also since it comes in various grades, finish and style. The price could vary from Rs 160/- to Rs 210/-. Even though the polish solution might not cost that much, the labor cost for PU polishing is quite high since it takes experienced labors to attain perfection. The labor charge will be almost 3 to 4 times the price of the PU Polish solution. For example, if the PU polish solution costs about Rs 200/-, the application will cost about Rs 600/-.
Advantages– Apart from the high resistance to stress and scratch, PU polish can withstand wear and tear and also does not wear off quickly. Though it is on the expensive side, it is cost-effective as compared to lamination finish. This polish also gives a superior-looking glaze compared to any other basic wood polishes. A minimum number of coatings can get the desired result and also this polish will be dried quickly after a coat whilst other polishes might take hours to dry.
Another key feature of the polish is that it is irreversible on the wood surface while on the metal surface the polish can be wiped off with the help of certain removers.
- Sanding– The first step to begin PU polish is to sand down the surface of the wooden furniture and sandpaper with bigger granules is recommended since it can easily chip away any irregularity and smoothens the surface perfectly.
- Filling– After sanding is down, it is important to fill the open pores, cut surfaces, or any other irregular dents on the surface of the furniture. Various brands of filling materials are easily available in the market today. After picking the right one for the furniture, the filling material has to be applied on the joints of the furniture first and then to the small openings and nail spots to conceal it well.
- Staining– Once the fillers are dry, the surface has to be sanded down with another sandpaper that has smaller granules to achieve an even smoother surface for a neat finishing. Staining of the wood is a process carried out to achieve desired color or shade to the surface of the wood. Various shades of wood stains are available in the market. Before staining the wood, it is essential to make sure that the surface of the wood is clean and dust-free as the stain wouldn’t adhere properly on a surface that isn’t free of dust, dirt, and grease.
- First coat of clear sanding sealer– Sanding sealer is an important step in PU polish. It is essential to make sure that the sanding process is done well before applying the sanding sealer. Clear PU sealer has to be mixed with its hardener and thinner in the ratio suggested by the manufacturing brand. After applying 1 layer of PU sealer with a spray gun, the surface has to be allowed to dry for at least 4 hours.
- Dry sanding with Orbit sander machine– Using a sanding plate of coarseness 400, the surface has to be sanded down with the help of any orbiter sander machine. The individual using the orbit sanding machine has to make sure that the sanding surface is smooth during the process.
- Second coat of White PU sealer– Second coat of clear PU sealer with the same ratio as the first coat of PU sealer has to be applied and left to dry for at least 4 hours.
- First coat of Clear PU top coat- The final step is to apply the clear PU top coat. The Clear PU top coat usually comes in two segments, hardener, and resins. These are well-blended in a proper ratio arrangement and have to be utilized within 8 hours of readiness. This clear PU top coat has to be applied using a spray gun that has an attached compressor and it’s recommended that an expert do this process since it’s an important step that requires perfection.
- Final Coat of Clear PU top coat- After letting the principal top coat dry for at least 6 hours, the surface has to be sanded again using a finer granule waterproof sandpaper to smoothen the surface. Later a second coat of Clear PU top coat can be applied to achieve a decent gloss and this time it has to dry for at least 24 hours.
- Buffing (Suggested only for high-gloss finish)- The buffing process is an important step that’s done to clean and polish the final surface to achieve the High Gloss finish of the PU polish. Buffing helps remove any blemishes, spray granules, and scratches and produces a smooth, shiny finish. Buffing creams and wheel pads are a few of the different items used for this purpose, each of which has its benefits and drawbacks if not used properly.
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