We all love shiny things. Maybe that is why diamonds are said to be a girl’s best friend. However, not all of us can afford diamonds, but that does not mean that we cannot settle for other equally shiny stuff like polished plastic. Plastic is used in various products such as taillights, turn signal lenses, and even eyeglass lenses. With time, the plastic becomes dull, and to bring back the glory of a transparent look, polishing it is the only way to go. If you have never had to polish plastic before, here is everything you need to know, including the various treatments, methods used, and materials you need. We will also tell you why it is important to know the type of plastic you are working with before you start your project. According to this article LinkedIn, there are various polishing plastic methods, and each depends on the particular project. Among them are:
The best thing about buffing is that it works for all types of plastic. Before you polish, you must consider the depth of the scratches you want to get rid of; shallow scratches require light abrasives while deeper ones demand sandpaper. Preparation before buffing and polishing is also a crucial step. Therefore, the first thing you need to do is clean the surface to remove any debris on the surface that would cause more scratches. A clean cotton cloth dipped in rubbing alcohol, or warm soapy dishwater will do the trick. You do not need out of the ordinary items to remove the scratches; some toothpaste applied in a circular motion on the surface, using a clean cotton cloth will help smoothen it. However, you have to be patient to get the desired results because it could take as long as ten minutes. If you prefer a toothpaste substitute, then baking soda will also work. Mix it with water in a ratio of 1:1 and apply it in a circular motion using a clean cotton cloth.
Keep rinsing off the residue and gently scratching the surface until you get the results you want. Since baking soda and toothpaste are for shallow scratches, if you are not pleased with the results after trying these two products, it is time to move on to sandpaper. According to Bob Vila, wet sanding smoothens the surface much faster than toothpaste or baking soda. The sandpaper has to be wet so that the moisture prevents further scratching the plastic. However, the process is similar to the other two products; starting with a fine-grit and moving on to the finest grit sandpaper. Once the plastic is smooth, the buffing will have caused it to lose its luster. Thus you will have to apply a polishing compound using a clean, dry cloth and in a circular motion.
Instructables details a guideline of how to polish plastic using a flame. The materials needed include a 300 grit sandpaper, a propane torch, tape for masking, orbital sander, and plastic, preferably acrylic, because polycarbonate bubbles up when subjected to flames. The first step is to protect the plastic from heating scratches; thus, use the tape to cover it before using the orbital sander to eliminate any disfiguring marks on the plastic. As per the article, you should keep the orbital sander at 90 degrees angle to avoid rounding out the edges, which would distort the plastic.
Next is cleaning the plastic to remove debris because any dirt present before flaming will melt into the plastic. Once clean, it is time to start flame polishing, and you will need to have practiced before or watched someone do it to avoid burning the plastic. It usually takes a few seconds, and any more than that, the plastic will burn, which is characterized by small air bubbles that cause the surface to become rough and never to be smooth again. Therefore, move over the surface as if brushing your hair and ensure that the area you are working in is well-ventilated; the torch emits carbon monoxide, which can be lethal if in an enclosed space. According to the article, the finished polish should resemble a bead of water running across the surface.
According to Star Rapid, vapor polishing is among the best ways of achieving optimal transparency in plastics; thus, it is mostly used for making lightweight optical high-quality lenses. However, as in all other plastic polishing methods, removing any scratches before polishing is a vital step in the process. Therefore, before vapor polishing, sand the surface using 1000 to 1500 grit sandpaper. This method has the advantage of being very fast because within a few seconds of application, the results are evident, making it very cost and time-efficient for large projects. It uses Weldon 4 gas to turn polycarbonate clear within seconds by melting its surface. Since the gas is highly toxic, one must use an active carbon mask, and the polishing must be carried out in a controlled environment. The room is also filled with the Weldon 4 gas, and once the process is complete, high-powered extraction fans get rid of the solvent gas.
Why it is Important to Know the Type of Plastic Being Polished
Most finishing materials are either polycarbonate or acrylate, commonly known as Plexiglass. Plexiglass presents more challenges during plastic polishing than polycarbonate because it is much more sensitive to scratches. Also, Plexiglass is available in two types: extruded and cast form. The former is much more challenging to work with because it breaks easily and is very sensitive to heat. As a result, polishing it using a machine or flame polishing can present more challenges because it could become more viscous. These difficulties of working with extruded Plexiglass are because it is formed under pressure thus has loads of internal stresses. On the other hand, while polycarbonate and cast form Plexiglass are easier to work with, they too can develop heat, mostly when polishing them using a polishing wheel.