If you’ve worked on a DIY project involving paint or wood before, you’re likely no stranger to sanding. Typically, sanding is the last drywall process and helps eliminate blemishes, scratches, gouges, and other imperfections. In essence, this procedure preps your wall for finishing touches.
Now, let’s talk about sandpaper. Did you know that sandpaper grit ranges from 24 up to 1000? Well, it does, and choosing the right grit is critical for the project at hand. Pick the wrong kind, and you’ll do more damage than good to your walls.
Not to mention, this damage will then need sanding with finer sandpaper. So, in effect, you will spend more time than necessary on the project. You may then ask, what grit sandpaper is best for drywall? Well, that’s the question we will answer with this article, so read on to find out!
Recommended Grit According to Projects
When it comes to drywall, projects may vary between a patch job, spackling, or painting. Not to mention the material of drywall application may differ as well. So this section will cover the grit sandpaper suitable for each of these different tasks.
For Drywall Patches
The best sandpaper for working on drywall patches is between 100-120 grit. People tend to have the misconception that starting with coarse sandpaper is beneficial. In reality, though, all this does is increase the time needed for the project and scratch up the wall. These will then require filling with joint compound meaning additional labor.
Also, it is advisable to attach the sandpaper to a sander pole instead of working by hand. Use the pole to sand over the walls gently. It is best to take extra care and apply only a mild amount of force along the taped seams.
Essentially, it helps to let the sander handle the work. When you apply unnecessary pressure to the sander, it can damage your walls by causing divots and other flaws. However, the pole is not as effective when sanding corners. You will want to switch to a hand sander like an orbital palm sander for these spots.
Once you complete a few passes with the 100-120 grit paper, switch up to a 150 grit paper. This grit sandpaper is ideal for finishing touches that are smooth and blemish-free.
This method of starting with 120 and finishing with 150 also works well for areas with rougher patches. Simultaneously, it is effective on corners and rough patches as well.
A typical repair job with spackling paste requires medium grit sandpaper, between 80 to 120. The exact grit depends directly on the spackling circumstances. For instance, if you are working on heavily damaged paint, you will need a heavier grit, around 80. This level of grit will allow you to strip the paint before you get to work on any repairs and repainting.
The lighter grit of 120 and above are fit for jobs that require light repairs and smooth finishing. One thing to bear in mind is that paint can take care of a lot of flaws. So if you are considering a paint job after the repair work, you don’t need to go beyond 120-grit sandpaper.
Before Painting Walls
No one grit paper works well before applying paint. Instead, you must use a combination of fine and medium-grit sandpaper to get the desired results. The reason being, coarser paper can be less time-consuming and strip materials quick, but it leaves you with more scratches.
Drywall compound tends to be soft by nature, so you want to avoid coarse paper like 80 or 100 grit. These will leave far more blemishes and require more time for fixes. Before painting, it is best to start with 120 or 150 grit paper and finish with 180 and 220.
If you find that you need to remove old paint from the walls, you may use 100 grit sandpaper. As with drywall, here too, you should move upwards through grit paper until you reach 220.
When sanding, be careful not to exert too much force, especially if you are using a sander pole. It is best to let the sander do the mechanical work than to apply pressure yourself.
For Already Painted Walls
Unfortunate as it is, there may be times when you need to sand over painted walls. For instance, you may notice a blemish you missed, or the paint may drip onto the wall. Whatever the reason, it is frustrating because it occurs right as you’re about to finish the project.
Nevertheless, if you want the job to be perfect, you need to give it due attention. For the smaller surface areas, 150 grit sandpaper should do the job. However, take care to sand only the problem spot, or else you may increase the damage.
Doing so will help you strip the paint and reach the drywall or primer beneath it. You can then make the necessary fixes for the perfect finish you expect. Finally, give the spot a once-over with 180 grit sandpaper before repainting it, and you should be good to go.
For Repainting Wood
Like wainscotting and crown molding, certain parts of a wall can have wood in them, either partially or entirely. It is not unusual that, over time, this wood may begin showing scratches and scuff marks. However, before you repaint these areas, it is best to roughen the surface a bit. For this purpose, medium-grit sandpaper around 120 will work the best.
However, if you do not intend to repaint the wood, consider sanding them twice. Use 120 grit paper first, and follow it up with 180 grit. The reason being, a second sanding with finer paper will lighten the remaining scratches caused by the coarse sandpaper. Without another sanding, these marks may show through the restaining.
You may also use this method when sanding baseboard floors.
For Oil Paint Before Latex Application
Before applying latex paint over oil paint, you will need to improve the adhesion of the surface. Typically, the method to do this involves the application of a conversion primer coat. However, you may skip this and use fine-grade sandpaper instead to make the surface rougher.
The best grit sandpaper for this project is 220. The rougher the old paint, the easier the new paint will adhere to it. So it will prevent the paint from peeling in the future.
How Grits Affect Materials
Each grit sandpaper has a specific purpose. So if you use it for something other than that purpose, you will find it doesn’t do the job.
If you want the perfect finish for your drywall project, it is crucial to choose the right grit sandpaper. An understanding of how different grits work will make doing so far easier. So in this section, we’ll take a look at both fine and coarse grit sandpapers in more detail.
Fine Grit Sandpaper
The fine-grit sandpaper class includes micro-abrasives and has higher numbers. These are the ones you usually rely on when your project involves wood or drywall.
|Ultra Fine||Most delicate||800 or 1000||P1500,
|8.4-12.6 micrometers||Final sanding;
Polishing thick finish
|Super Fine||May wipe away small patches and irregularities; not strong enough for removal.||400, 500, 600||P800, P1000 or P1200||15.3 to 23.0 micrometers||Final wood finish|
|Extra Fine||Less fine and more abrasive than Super Fine||320, 360||P400, P500 or P600||25.8 to 36.0 micrometers||Initial wood polishing|
|Very Fine||Least fine||240||P240, P280, P320 or P360||40.5 to 58.5 micrometers||Sanding finish for drywall, wood, and sequential paint coats|
Coarse Grit Sandpaper
Medium and coarse grit sandpapers fall in the class of macro grit abrasives. These are the ones you usually go for when working on rougher wood or metals.
|Very Fine||Coarser than the micro-abrasive Very Fine||150, 180, 220||P150, P180 or P220||190 to 265 micrometers||Bare wood sanding|
|Extra Fine||Can’t remove paint or varnish from wood||100 or 120||P100 or P120
|115 to 162 micrometers||Cleaning plaster, removing wood water stains, preparing wood for finishing|
|Medium||Medium to coarse surface texture after sanding||80||P60 or P80||190 to 265 micrometers||Bare wood sanding to get it ready for varnish removal and final finishing|
|Coarse||Can remove material quickly||40, 50, 60||P40 or P50||336 to 425 micrometers||Wiping debris layer or minimal effort finish|
|Extra Coarse||Quickest at removing materials||24, 30, 36||P12, P16, P30 or P36||530 to 1815 micrometers||Initial hardwood floor sanding|
Selecting the Right Grit Material
Sanding paper varies not only in grit density but also in the paper’s abrasive material. So naturally, this tends to influence the quality of your sanding project as well. Of course, manufacturers typically denote which materials work best with their sandpaper products.
However, you can never go wrong when you know which grit is best for your project. So here’s a list of common grit materials along with the surfaces that suit them.
- Aluminum Oxide: Among the more durable synthetic grits is aluminum oxide. Typically, you rely on this grit sandpaper for hard surfaces like metal, including bronze and alloy steel. Also, it is a suitable option for sanding all hardwood floors.
- Emery: This grit sandpaper comes from a natural grain. It works best when used to eliminate corrosion or to polish metals like steel. You want to avoid using this sandpaper when working on wood as its particle edges are quite sharp.
- Flint: Flint, too, is a natural grain sandpaper grit. If you want to sand off surface coats like varnish or paint, this is the grit you want.
- Garnet: Our third natural grain is garnet, which is softer than both emery and flint. This one works best on wood as it is too dull to use on metal.
- Silicon carbide: Perhaps the most enduring among synthetic abrasives is silicon carbide. This grit sandpaper is suitable for various materials, including metals, plastic, softwoods, and hardwoods.
- Zirconia alumina: Another synthetic product, zirconia alumina, is a durable grit best suited for metal. You may also rely on it for the first sanding of rough wood. The benefit of working on metal with this grit is that its particles become sharper. So it eliminates the need to change the paper repeatedly.
How to Read a Sandpaper Sheet
With sandpaper sheets, you must know precisely how to read them so you can pick the right one. Earlier, this wasn’t as necessary because companies would print the grit size, type, paperweight, and even the glue used. The sheet would also tell you whether it is an open or closed coat.
Now, however, it is challenging to find a sheet with that level of detail. The only information you will always find is the manufacturer’s logo and the grit size. However, understanding this detail can be confusing, and here’s why.
The US bases sandpaper grading on the Standard Scale, per which the numbers get higher as the grits get finer. However, if you find the number preceded by a “P,” it denotes the European system. This system is similar to the Standard Scale till 240 grit, but distinctions emerge as the grits become finer. For instance, a Standard 400 is equal to a P800.
Grit number accompanied with a Greek letter µ signifies a micron grading. In this reading, the numbers get smaller as the grit gets finer. So, a 60µ is nearly equivalent to a Standard 240. These sanding papers tend to be the priciest of the bunch with a plastic film backing. Most often, auto-body refinishers and furniture makers are the ones to rely on them.
Tools for Using Sandpaper
Once you have the right sandpaper type and grit, the next step is, you guessed it, sanding! Sandpaper is quite versatile, so you can fold it into a palm-sized square and refold it as a side dulls.
However, sanding by hand can be tedious and inaccurate when the sanding area is large. So in these situations, it is best to rely on a sanding tool. Here are a few popular ones for you to consider.
- Manual hand sander: These inexpensive tools are excellent for sanding large areas like the sides of a bookcase.
- Sanding sponge: Since these come with a flexible sponge, they are ideal for sanding rounded edges. Some may even have a beveled side to make sanding easier in tight spots like stair baluster bases.
- Vibrating palm sander: This electric power sanding can support a plethora of sanding plate shapes. All you need to do is attach the sandpaper, turn on the tool, and gently guide it around the area.
- Orbital sander: Orbital sanders either hold cut pieces of regular sandpaper or pre-cut sanding pads. They are most useful for sanding flat areas.
With this article, you now have a complete guide to which sanding grit is most suitable for your drywall project. So, remember to verify the grit size because patches, spackles, and paint jobs all have particular sandpaper that suits them.
Also, don’t forget to pay attention to the grit material because using the wrong kind can damage your walls. Finally, pick the right tool based on the size of your project. Remember, when it comes to sanding work, skimping is never an option if you want that picture-perfect finish!