Sanding Basics and Best Practices

Are you here to understand about what sanding is all about? May be you are planning to get your floor sanded by your professional or may be you are planning to get your hands dirty by doing it yourself. In this post, I’ll clear all the basics of sanding, so that you can talk confidently with sanding professional. It will also help you in finding the best sander for your diy sanding works.

What is Sanding?

In a very simple words, sanding is a process of smoothening of the wood surface. You can smoothen the surface of the wood by abrasion using a piece of sandpaper. You can sand a small piece of wood in less time, but if you are planning to sand a bigger blocks or a wooden floor, you would need a sander machine.

What is the purpose of sanding?

The purpose of the sanding is to flatten the uneven parts of the surface. It also helps us remove any stains on the surface. If you are planning for repaint, sanding will help in removing the old paint job. If you are planning to glue the surface, you can also sand the surface to make it rough which helps in holding the glue.

What is a Sander?

A sander is just a machine that automates the repeated boring process of abrasion and turns it into a fun activity. Sanders come in variety of ways to attach a sandpaper to it. Once the sandpaper is attached, the sander will either rotate or spin and does all the hard work of sanding the wood.

There are different types of sanders available for each type of project, popular among those are Random Orbital Sanders, Belt Sanders, Detail Sanders, Disc Sanders and Drum Sanders.

Why do we use sandpaper in Sander?

As mentioned above, the main objective of a sander is to automate the sanding process using a sandpaper. And the broad range of options that we get with sandpapers give us the flexibility to sand the surface according to our need of the project. A sandpaper contains abrasive material of different grit sizes which further increases the options.

What is Grit Size in a Sandpaper?

Grit size in a sandpaper is the rating given to the abrasive material used for the sandpaper. The smoothness of the wood after sanding depends on the grit size of the sandpaper you used. Lesser Grit sizes produce more coarser abrasion than the higher grit sizes.

Sanding with lesser grit sizes may go out of control and remove more than what you want to sand. So you need to make sure that you are evenly spreading across the wood. Lesser grit sizes produce scratches or swirls on the wood which are more evident when you are staining, so you need to finish it with a higher grit sizes sequentially to get rid of those and get the finer smoothness.

Types of Sandpaper

Understanding the abrasive material used in the sandpaper will help in selecting the right sandpaper for your project.

Aluminum Oxide Sandpaper

Chemical compound of Aluminum and Oxygen produce one of the more versatile sandpaper called Aluminum Oxide that can be used for sanding the dry walls, wood, plastic and metals, though mostly preferred for wood sanding. These are the sand papers that are mostly used along with power tools.

Silicon Carbide Sandpaper

Silicon Carbide sandpaper is for more coarser sanding and capable of sanding dry walls, wood, plastic and metals, just like Aluminum Oxide sander. It can also be used for wet-sanding as the material is water-proof.

Ceramic Sandpaper

Ceramic Sandpapers are made of synthetic material. They are very durable and can perform more aggressive sanding. They are best to be used along with power tools, but are expensive too. Ceramic sandpapers are mostly used

Garnet Sandpaper

Garnet Sandpaper are made out of crushed Garnet. They are the most used house hold sandpaper with natural abrasive, mostly used for wood working.

Emery Sandpaper

Emery is also another natural abrasive substance and used for metal sanding. However, you can control the coarseness by choosing the right grit size for your project.

How many grits should I use before I apply the finish?

Always start sanding with lower grit size and work towards the higher grit sizes. How many grits to be used is all depends on the surface you are sanding. If you are sanding bare wood, start with 180 grit and 220 grit to smoothen out the surface or to remove old finish or scratches. If you are sanding hardwood you need to start lower grit sizes like 36 and work towards 100 grit. You should make sure that you are changing the grits sequentially instead of jumping them. You may also start with a Aluminum Oxide and finish it with a Silicon Carbide to get a superior finish.

Do we need to sand before staining?

Yes, sanding before staining will help to get rid of any scratches or swirls and blemishes from the surface. If you stain without sanding, the swirls or scratches gets highlighted, so you must always sand before staining, but don’t sand it too far as some of the stains will not hold on to the fine sanded surface.

How do you know when you’re done sanding on the wood?

To check whether the surface need further more sanding, flash a light on the surface from different angles and see if you see any swirls or scratches. Furthermore you can also lift the grain with water washing before you sand the surface one more time with an extra-fine grit size sandpaper to remove the raised grain.

Should we apply stain immediately after sanding?

It is a best practice to apply the finish right after sanding for better results. Though keeping the surface open after sanding for few days doesn’t matter, dust and weather might affect the surface. Also, some water based finishes would require the surface to be fresh. However, shellac and oil-based varnishes do not have any problem even if you apply after few days after sanding. But as a general rule of thumb, it is always better to apply finish right after sanding the surface.