Understanding Floor Sanding Grit Options
Floor sanding can be quite confusing for amateurs from the procedure itself to the equipment. What is perhaps the most confusing aspect is selecting the grit size. So what exactly is grit? Why does it matter that you get the size right?
Let us take at this and a lot more that you need to know even if you won’t do the floor sanding yourself.
What is used to make sandpaper?
First off, it would help a lot if you understood exactly what sandpaper is made of as this plays a huge role in determining grit and the sanding effects. Despite the name and texture, sandpaper is not made from typical sand.
Instead, it has minerals like aluminium oxide or garnet glued onto a sturdy paper base. The minerals have jagged endings that cut through the different layers worked on during floor sanding.
What is grit size?
By definition, grit size is the level of abrasiveness on the mineral-coated side of sanding paper. It is determined by the size and distribution of the minerals earlier alluded to on the paper.
If the minerals are smaller and more in number on the paper, then the grit size is high. These tend to have a fine feel to them and are used for more delicate parts of the floor sanding process.
On the other hand, if the minerals are larger and fewer, the grit size is given a lower grade. These tend to be coarse with the jagged ends being more pronounced and therefore ideal for effective cutting through thicker layers.
Different grit options and their applications
Grit sizes range from 12 to 600 with most sanding paper minerals. These sizes are further grouped based on certain ranges for different purposes. Here are the 3 main categories and what the different grit grades in each are.
- Coarse Grit
This is typically grit size of less than 40 and as the name suggests, it feels quite coarse even to the touch. Sanding paper in this category is very effective when it comes to cutting through tough or thick layers whether it is old polish or damaged top layers of wood flooring.
In addition to removal of such layers, this category is ideal for evening out surfaces. It could be for warping that creates bumps or even dented surfaces.
Typically, coarse grit sizes leave deep scratch marks on the surfaces that they are used on. They are therefore only applied during the first stripping and sanding parts of the floor renovation process.
- Medium Grit
Grit sizes between 50 and 80 or even 100 are considered medium grit. These are used for basic sanding after the top coat has been stripped off the surface. They are finer than the coarse grit options and therefore ideal when it comes to correction of the deep scratch marks left in the first step of floor sanding.
They may also be used as the first step sanding paper options for lighter flooring material or where no intense cutting and stripping is required.
However, the medium grit sanding paper also leaves scratch marks of its own, albeit much shallower than those of the coarse option. This means that they can never be used in final floor sanding stages.
- Fine Grit
Any grit size above 100 is considered fine. There is a super fine category of grit sizes above 220 but these are commonly lumped in together with the general group.
Sanding paper here has more particles of the sanding minerals spread out over the surface. The particles are also much smaller with less jagged ends. As a result, this category is ideal for finishing where their size allows easy elimination of imperfections like scratch marks left in previous parts of the process.
In addition to final sanding, fine grit sanding paper can be used to polish final layers of protective coats for a smooth and glossy finish.
What happens if you use the wrong grit size?
We have summarized everything for you based on pretty broad categories. While it does give you a good idea of what different grits are for, accurate selection is based on experience. Here is exactly what could go wrong if you made the wrong decision on grit size.
Coarse grit is very jagged and great at cutting through surfaces. If you use it too late in the sanding process or on more delicate materials, you will end up leaving unsightly scratch marks. These require re-sanding which is both a waste of time and energy.
Overusing grit size could also lead to unnecessary stripping which leaves your flooring panels thinner than they needed to be. The rule is once you have stripped away the top layer you need to move on to something finer.
This is the more common mistake when it comes to DIY floor sanding that ends up costing homeowners a lot. The sanding paper will not actually damage your floors. However, when used for cutting and stripping it is unlikely to survive the process.
What happens is that the paper gets clogged up with debris really fast. You therefore have to keep replacing them multiple times in one project which is a huge cost. It also requires a lot more effort whether you are hand sanding or using machinery just to see any results.
Play it safe and go with the pros
Understanding the technical aspect of grit is definitely important as a homeowner. However, this does not mean that you are ready to go off sanding your floors by yourself. This is because in addition to the technical knowledge, a lot of experience is required to know exactly what grade to use. This is based on factors like the type of material, the extent of damage, and so much more.
Therefore, in order to avoid making any mistakes and ruining your floors any further, it is best to find and work with experienced professionals in the floor sanding business. They know everything there is to know about good floor sanding for beautiful and long lasting results. So find the best floor sanding crew in your area and get full value for your investment.
Bona Gap Master