Why Is My New Pool Plaster Rough?

If your inground pool has a concrete base, then it requires plaster to have an aesthetic appearance and act as the first line of defense against water leakage. But among the functions of a liner is smoothening the pool surface and interior, so it isn’t rough to brush up against. It is, therefore, reasonable to be disappointed upon getting new pool plaster and discovering that it is still quite rough.

New pool plaster is rough because it isn’t even and bleeds calcium that can lead to scale buildup. It requires surface preparation before it is ready to carry water without scaling. The plaster can naturally smoothen with a few drain cycles but should be washed and sanded first.

In this brief post, we will cover the various things you can do to smoothen your new pool plaster. These solutions will range from low-effort to high-effort and investment options. None of these are mutually exclusive, so feel free to use all of the methods listed in this article.

How to Reduce New Pool Plaster Roughness?

To reduce new pool plaster roughness, you need to sand it down and wash it a few times. You can also apply sealant, but that’s not a cost-effective method to make your pool plaster smoother. To reduce the cost of this process, you should avoid filling your pool right after plaster.

Let’s look at the specifics of each solution. Here are three ways to reduce the plaster roughness.

Triple-Sand the Pool Plaster

If you’re reading this, you have probably sanded the plaster already. This can make you think that something is wrong with its application. However, you actually need to sand down new pool plaster three times before it is smooth enough to feel normal. 

Sanding down this way is a requirement because the layering of plaster is different in a pool than it is in concrete house construction and water exposure is a factor that is present more prominently in swimming pools.

For the following, the pool will need to be drained and free of any liquids. First, use 80 grit sandpaper to even out any areas that are more obviously rough. These could be a few patches or the entirety of your swimming pool surface because of wrong application. 

Depending on how well and evenly the plaster is applied and any consequent scale buildup, you will need to sparingly or thoroughly sand the surface with an 80 grit sandpaper on a sanding block. At this stage, you can use more force than the sanding sessions down the line.

Using 120 grit sandpaper stuck on a sanding block, you should sand the plaster once again. Since evenness is important at this stage, you should not sand with extreme force. While force helps in the first sanding session, it is only feasible for rough patches and cannot be applied consistently across the pool interior. There will inevitably be a point where the force with which you’re sanding will decrease. 

That’s why you should sand the plaster with the strength that you can keep consistent and cover the plaster surface once. Here, you should not just sand where you feel the surface is rough but also areas that you think are smooth.

After this, you can conduct a touch-check to see if the swimming pool plaster is up to your liking. Many pool owners might consider the plaster smooth enough and hope to have the next few drain cycles smoothen it further over time. However, it is better to go forward with yet another sanding session. This time, you’ll use 240 grit sandpaper.

With fine sandpaper, you will remove unevenness that even bare skin can barely detect. Here, using force can be counterintuitive, and it is advisable to use little force as you lightly sand the plaster. Cover the entire pool surface. Once done, you can call it a day (or week if it took you that long). Your pool surface is smooth.

Wash the Calcium Away

As you now know, one of the greatest sources of pool plaster roughness isn’t the unevenness of the plaster but is actually the scale deposits that come from calcium. Calcium is bled into the pool water by fresh plaster and can lead to almost immediate scale buildup in the pool walls. 

If you have plastered your pool anew, you can proceed directly with washing the walls so water can take excess calcium out the drain. This is much better than having the walls marinate in high-calcium water, which is the case when you fill the pool with water after applying fresh plaster.

But even if you have filled the pool up, you can always drain and wash the walls. In fact, even after sanding away the deposits and clearing the residue with sanding paper, you can still wash the walls to make sure you’re getting rid of as much excess calcium as possible. Regularly sanding pool plaster is no fun.

Once you wash away the calcium, make sure you pour descaling liquid through the pool drain to make sure the scale buildup doesn’t happen in pool pipes. While having rough pool walls can be rough, having blocked plumbing can be worse as it ruins your pool pumps and drives up electricity consumption.

Coat the Plaster

This isn’t as mainstream a choice, but you can apply a sealing layer over the pool plaster to keep it from interacting with water. This prevents deterioration in the long run, but most pool owners consider this to be frivolous as the role of the plaster itself is to be the first line of defense against water leakage. Still, epoxy coating is quite economical as is waterproof sealing paint, both of which can extend the lifespan of the pool interior.

Final Thoughts

Your pool plaster is keeping water from seeping past concrete and from simply leaking out of the pool. To that end, it does not need much preparation. However, if you don’t want to feel coarse scales across your pool walls, you might want to keep the pool from becoming calcium-dense. New plaster itself can be a source of calcium release so washing it a few times and then using descaling liquid to safeguard the drain is a great solution. As for the roughness that your plaster currently has, we recommend triple sanding going from coarser paper to finer with each session.

Jed Arnold

Jed spent every year from the ages of 15 - 22 as a Lifeguard (Red Cross) and ages of 17 - 22 as a Certified Pool Operator (CPO). Between working for over a dozen facilities and owning a pool, he carries over a decade of pool experience.

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