We discussed various sanding methods in part one of this post. Here in part 2 we will move on to more techniques, starting with the amount of sanding to be done.
The majority of beginners’ sand more than is required. They will start with the lowest number grit and progressively move up, one grit level at a time. All of this extra work is not necessary, as most beginners will eventually find out. You basically need to use only three pieces of sandpaper, a course grit, a medium grit, and a fine grit. Properly using these three grits will produce the smoothness in the wood that you require. As they say, continual practice will make perfect.
There are different techniques to sanding depending on what you are working on. For example, if you use a water base finish, a lacquer, shellac, or a varnish you will not require any further heavy sanding. Each of these products creates a particular surface finish of its own after applying a few coats of the product. Some people like to use a #180 grit sandpaper after the finish thoroughly dries, but this is not always necessary.
Oil based or varnish and oil blends do require additional sanding between coats. The reason why they do and the above products do not is because of the buildup. The above products have a measurable build up after each application but the oil based products do not have any measurable build up. Therefore, the coarseness of the wood will be both visible and noticeable when handling.
However, each of the oil-based products can be ultimately as smooth as you desire by sanding between coats. Use a #400 grit or #600 grit sandpaper and lightly sand the piece that you are working on after applying the oil-based product. Do it while it is still wet and sticky. As a side point, you should only use the high number grit sandpaper’s on oil-based products with a mechanical vibrator or random-orbit sander.
When staining a wood product you will notice that the stain intensity will lessen the more you sand with a #180 or #220 grit sandpaper. However, if you desire that the stain be less intense, then you should continue to use these two grits of sandpaper. If you use a random-orbit sander you need to be careful that you do not leave wavy marks on the wood. A random-orbit sander however is more efficient than your vibrator type sanders.
If you have any of these wavy marks on your project you can remove them by hand sanding. Always make sure that you sand in the direction of the grain. Sanding in the direction of the grain is doubly important when you are using a stain. However, sometimes it is impossible to sand in the direction of the grain when using veneer patterns that are decorative, such as we find in marquetry and sunbursts.
When you sand across the grain it tears the wood fibers. This will make scratches more noticeable, especially when applying a stain. A scratch will be less noticeable and often disguised by the grain when sanding in the direction of the grain. Cross grained sanding is sometimes unavoidable. Always have a practice piece of wood to determine which sanding direction is best suited for your project. Otherwise, happy sanding for all your projects.