When it comes to choosing the best grit sandpaper for PVC, it's important to consider a few factors. You want to select a sandpaper that will effectively roughen the surface of the PVC pipe, allowing the paint to adhere properly. However, you also want to avoid using sandpaper that is too coarse, as it can damage or wear down the pipe too quickly.
A grit of 220 or higher is generally recommended for sanding PVC. This grit is fine enough to create a roughened surface without causing significant damage to the pipe. However, it's important to note that the specific grit you choose may also depend on the condition of the PVC pipe and the type of paint you plan to use.
If the PVC pipe is already in good condition with a smooth surface, you may be able to start with a higher grit sandpaper, such as 320 or 400. These finer grits will create a more subtle roughness, which can be sufficient for paint adhesion. However, if the PVC pipe is rough or has imperfections, you may need to start with a coarser grit, such as 180 or 220, to effectively smooth out the surface.
Avoid using an electric sander when sanding PVC, as the high speed and pressure can quickly wear down the pipe and potentially create flat spots. Instead, opt for manual sanding using a sanding block or sanding sponge. This will allow you to have better control over the sanding process and avoid excessive damage to the PVC.
When sanding the PVC, be sure to apply consistent pressure and sand in a circular or back-and-forth motion. This will help to create an even roughened surface and ensure that the paint will adhere properly. Take your time and periodically check the surface to see if it has achieved the desired level of roughness.
In my personal experience as a brewer, I have used sandpaper with a grit of 220 for sanding PVC pipes before applying paint. This grit provided a good balance between creating a roughened surface for paint adhesion and avoiding excessive damage to the pipe. However, it's always a good idea to consider the specific condition of the PVC and the type of paint you plan to use before selecting the grit of sandpaper.
To summarize, a grit of 220 or higher is generally recommended for sanding PVC pipes before painting. However, the specific grit may vary depending on the condition of the PVC and the type of paint being used. Manual sanding with a sanding block or sponge is preferred over using an electric sander to avoid excessive damage to the PVC. Take your time, apply consistent pressure, and periodically check the surface to ensure it has achieved the desired level of roughness.