Refinishing a hot tub is an option when the acrylic or fiberglass coating has cracks or other damage. New hot tubs can be expensive, so instead of purchasing a new one, repair the damage for much less money. An extra bonus is that you can change the color of your hot tub's interior by adding a colored tint to the paint kit.
Preparing Your Hot Tub
Empty the water from your hot tub. Turn off all pumps and jets and disconnect the power supply. Pull out the drain plug and allow the water to drain completely. Use the wet/dry vacuum, if necessary, to remove the small amount of water that won't drain through most drain holes.
Sand the entire inside surface of your hot tub with the 100-grit sandpaper. If necessary, wipe your sanded areas with damp rags to see where you've already sanded.
Fill the 1-gallon bucket with water and carefully add ½ the muriatic pool acid and mix well. Follow the manufacturer's instructions and precautions completely.
Wash the entire inside surface of the hot tub, using the scrub brush and dipping it into the bucket. Start at the floor and work your way up to the inside rim. This allows you to use the seat sections to keep your body from contacting the muriatic acid wash.
Rinse the area thoroughly, using the water hose. Again, use the wet/dry vacuum to remove any remaining water that doesn't drain out. Allow the hot tub to dry completely.
Mix your spa paint. Pour ½ of the clear resin into one of the 2-qt. buckets. If you have a tint or your paint kit came with a colored tint, add ½ of the tint into the clear resin in the bucket and mix thoroughly with a mixing stick.
Add ½ the hardener (may be an amber color) into the same bucket and mix thoroughly for about five minutes.
Hot Tub Painting: Roll-On Technique
Pour some of the spa paint mix into a roller paint tray. Roll the pad, on the roller, through the paint well in the tray and roll up and down the grooved section to evenly cover the pad with paint.
Apply the spa paint to the hot tub interior from bottom to top. Start at the floor and work your way up to the rim. Use evenly rolled and overlapping strokes. Roll more paint onto the roller as needed.
Cut in around the jets and fixtures with a paintbrush; try to maintain the same thickness. Allow your paint to dry 24 hours. Use the remaining halves of the mixtures for the paint, mixing in the same manner as you did for the first coat of paint.
Add a second coat of paint when the first coat is completely dry, using a new roller pad and tray. Allow this coat to dry for about three days before you refill your hot tub.
Hot Tub Painting: Brush-On Technique
Dip your paintbrush into the paint bucket.
Apply the spa paint to the interior of the hot tub from the floor to the rim at the top. Use even and overlapping brush strokes for uniform application.
Apply spa paint around the jets and fixtures. Allow your paint to dry for 24 hours.
Apply your second coat in the same manner with a second brush.
Refill your hot tub when you have allowed the spa paint to dry for at least three days.