How to Prepare Your Pool Surface for Painting in 9 Steps

After you’ve established what kind of pool paint you need, it’s time to prepare your pool surface for painting. It may be a slightly tedious process but a necessary one if you’re trying to complete your project and have it be well-executed and long lasting. The steps to remember in your head are: “Wash. Etch. Wash again.” Simple enough.

Washing

Washing out your pool is vital in making sure the whole process starts off on the right foot. Whatever coating you picked for your pool based on our previous post won’t adhere properly to your existing pool surface if it isn’t washed thoroughly. Gunk builds up on pool surfaces from use. Residue like sunscreen, body oils, hair products, algae, or pool chemical buildup can cause separation between the pool surface and a new coating. Here are the best steps for properly washing your pool.

Step 1: Mix Washing Solution

Use a washing solution like Olympic No. 901 pool washing compound (or anything else that’s a tri-sodium phosphate compound) mixed with warm water. DO NOT use a soap or detergent. These leave behind a film that results in poor adhesion.

According to the Kelly Tech website, you should mix 8 oz of pool washing compound or tri-sodium phosphate to each gallon of warm water. One gallon should cover 200 square feet.

Step 2: Wash

Dip a long-handled brush in the solution and firmly scrub the pool in about 10 sections. Remember to scrub the walls first and floor last.

Step 3: Rinse

Rinse immediately after scrubbing, not allowing the solution to dry on the surface.

Acid Etching

Sounds a little scary, but don’t let the name of the process frighten you away. Acid etching is an absolutely necessary step. Before you get started, makes sure you wear protective eyewear and gloves. You can get fumes in your eyes if you don’t follow this simple rule: NEVER pour water into acid. ALWAYS pour acid into water.

Acid etching is required on bare masonry surfaces like concrete or plaster or for removing mineral deposits or residue on a previously coated pool. Acid washing is effective because it opens up the pores of the surface and allows the subsequent coating to grab onto the surface and create a strong bond. Even on previously coated pools that are sometimes recommended to just be sanded, an acid wash is a surefire way to ensure your pool is prepped properly.

Step 4: Mix the Acid

Use a plastic bucket and mix 10% solution of muriatic acid (often available at pool supply or home improvement stores) in water. REMEMBER: pour in acid FIRST and then add water. Most muriatic acid comes packaged at 20% or 30% strength. One gallon of 30% muriatic acid mixed in two gallons of water will yield three gallons of 10% solution. Similarly, one gallon of 20% muriatic acid mixed with one gallon of water will yield two gallons of 10% solution. One gallon of 10% solution will cover 100 square feet of pool surface.

Step 5: Etching

Brush the solution on the surface. The acid should bubble when applied. As soon as the bubbling stops, rinse it off with clear water. If done properly, the surface will feel slightly rough like a fine sandpaper.

Step 6: Rinse

As you’re rinsing, if the water soaks into the surface then you’ll know it’s properly etched. If the water stands on the surface, you might have to etch that section again to ensure proper adhesion.

Step 7: Wash again

MAKE SURE you wash the pool again with your tri-sodium phosphate solution after etching. The solution will neutralize any acidic traces that may be left clinging to the surface.

Step 8: Rinse Again

Wash off the trisodium phosphate with clean water before it can dry.

Step 9: Let it dry

After washing a second time, let the pool dry completely before coating with either a primer or your chosen paint selection. If you use a Poxoprime II epoxy primer, you can prime directly over a wet surface so no waiting is necessary! Just be sure you DO NOT mix this primer in a galvanized metal container.

Fiberglass Pool Prep

If you’re preparing a fiberglass pool, you’ll want to sand the surface with coarse sandpaper. DO NOT use an orbital sander (handheld sanders that move in a circular motion). The sanding process will prepare it for a good epoxy coating bond. Once it’s been sanded properly, wash the pool as previously detailed—acid washing isn’t necessary. Allow to dry completely and you’re ready to resurface your pool!

Make sure you read our guide on choosing the right pool paint for your surface and how to paint your pool.