Which Grit Sandpaper for Deck Sanding?

November 20, 2022

You can use 80-grit sandpaper and a palm sander for sanding hard-to-reach areas that larger machines can’t easily access. You can also use 100-grit sandpaper for the railing, especially if you need to remove an old heavy coat. You can also do two passes of sandpaper, one with the 80-grit and the other with 100-grit sandpaper. Afterward, you can vacuum the deck or use a leaf blower to do away with the dust. Then, sand again using 100-grit sandpaper and clean off the dust again. You can apply the finish afterward.

One crucial step in staining your deck is the sanding process. Sanding your deck before applying a stain is an excellent way to enhance the smoothness of the finish. Besides, you will indeed get the preparation right if you use the right tools and the appropriate sanding grit when sanding the deck. With the correct sandpaper grit, you can simplify the sanding process and make your new deck or old deck appear good for several years to come.

Two factors you need to consider when choosing sandpaper for deck sanding: 

• Deck condition.
• The amount of sanding required.

Sanding for Quality Finish

The sanding process of the deck is a crucial step in finishing or staining the deck. Hence, you can’t sidestep or skirt around this process. Moreover, when sanding, you need to do it with ease and correctness. So, before asking how to best stain your deck, you should first ask how to best sand your deck. 

Once the deck panels get positioned and installed, they stand unprotected from the harsh environment of the outdoors. Their color will deteriorate if you let them stay there unprotected. 

Nevertheless, it will help dry the deck before you stain it entirely. It will help if you prepare the coating before adding the stain. Besides, the deck needs sanding to remove old paint and smoothen the surface. Moreover, you can remove rough edges and splinters as you sand. 

Sandpapers come in different grit or coarse. So, you need to select the best grit of sandpaper. The thing is, you should not sand the deck to glass-smooth perfection. You will give the wood a hard time absorbing the stain if you do so. If you use high-grit sandpaper, you risk making the pores impervious to stain.

Moreover, some wood types like redwood and cedar get damaged by hard sanding. So, it will help if you sand correctly to avoid damaging the deck panels. 

Guides on Choosing the Right Sandpaper Grit

As mentioned above, the quality of your deck finish will depend on the way you sand and finish the deck. It also depends on the type of wood you use for your deck panels. If you are using a hardwood like redwood, you need to smoothen the surface of the hardwood panels to ensure a quality finish. You can use up to 20-grit sandpaper for the first sanding. Afterward, you can use progressively finer ones for the best surface preparation for the redwood deck. 

If you’re using softwood for your deck, you can damage the wood surface, primarily if you use power tools. Therefore, it will be best to use 50-grit sandpaper for first-time sanding the softwood deck. If you don’t want to sand manually, you can use orbital or oscillating sanders for softwood. 

If you would sand pressure-treated lumber, however, you should take extra care not to inhale the dust. Pressure-treated timber are treated timber, and thus, it contains preservative additives or chemicals that can be harmful to your health. You should also use 60-150 grit sanding paper for your pressure-treated deck panels.

Why Should You Not Aim for a Glass-smooth Surface?

You can use 60 to 80-grit sandpaper using your power sander. The thing is, you don’t want to create the smoothest possible surface when sanding decks. The reason for this is that you might make it difficult for the wood to absorb the stain if you smoothen it too much. Thus, you must avoid the finer-grit sandpapers. Remember that if you go for the smoothest finish, the wood’s pores get clogged, preventing the stain from being absorbed by the wood. 

It will be best to go for medium-grit sandpaper when sanding deck panels. You should also use medium pressure on your power sander. You can use 60 to 80-grit sandpaper when sanding the deck panels. But when sanding the railings, you can use 80 to 100-grit sandpaper. You can sand the railings manually because it is hard to sand using the larger sanding machine. As a caveat, you should also avoid sanding the railings to glasslike smoothness, for the stain will also find it hard to penetrate the railing wood. 

Remember that the grit size refers to the number of coarse particles in the sandpaper. When the number is less, it means it is scratchy. If it is high, then it is more abrasive. With finer grit, you will notice a sizeable number of scratches, leading to a smoother finish.  

How Can You Optimize the Use of Various Sandpaper?

Sandpaper comes in different types like abrasive, non-abrasive, and resin-coated. If you want sandpaper that doesn’t quickly clog, you should go for resin-coated sandpaper. 

However, abrasive ones feature silicon carbide or aluminum oxide particles to remove stains or paint, while non-abrasive ones use less abrasive agents like zirconium dioxide and titanium dioxide. 

Sanding Natural Wood Deck or Pressure-treated Deck

Choosing the correct grit of sandpaper for your deck type will be best. If you got a natural wood deck, you need to use more abrasive or coarser sandpaper, while if your deck is a pressure-treated one, you should use finer grit paper because this type of deck is more resistant to abrasion and wear and tear.  

When sanding stained or painted decks, it will be best to use various sandpaper grits. Begin sanding with 80-grit sandpaper to remove old stain or paint. This way, you can remove old paint or stain. 

Then, transition to using 120-grit sandpaper to prepare your deck for refinishing. You should thoroughly clean the deck whenever you alter the sandpaper grit you are using. 

Sanding Your New Deck

Before sanding your new deck, you should let it thoroughly dry. Leave the deck for a month or more, depending on the weather in your place, before applying a finish. The drying process, of course, may take longer if the deck is pressure-treated. For some pressure-treated decks, you may wait for six months before you can apply the finish. 

You can test for dryness by sprinkling water onto the wood’s surface. If the water forms beads on the deck, you should let it dry further. After determining that the deck is ready for finishing, you can finish the deck. 

Determining the Grit of Sandpaper, You Need to Use

The amount of grit sandpaper you will use will depend on several factors. First, it will depend on your wood type and the deck. If it is of softwood and exhibits optimum condition, you will need 60-grit or 80-grit sandpaper. If it is of hardwood and displays poor condition, you will need 100-grit or 120-grit sandpaper.

Some people would even recommend starting with coarser sandpaper, like the 20-grit sandpaper, for the initial pass, then progressing to medium grit. This might be effective, but it means more sanding work. So, if you want to save on some elbow grease, you can simply sand the deck using 60-grit to 80-grit in one go.

Conclusion

Sanding is a crucial step in preparing the deck for staining or painting. As such, you should not sidestep this process, for it is necessary. Before sanding, you should check the deck for protruding screws or nails and countersink them before beginning to sand. These protruding nails might rip the sandpaper once it passes over those nails, thus delaying your work. 

It will be best to use a belt sander when sanding large deck surfaces to speed up the sanding process. Moreover, if you need to remove old stains, you should use coarse-grade sandpaper, then go for the finer grade for a smoother finish. You can also use a finishing sander for sanding the corners and edges. Besides, you should not forget to sweep the surface with a broom or vacuum the deck surface before applying a stain.