Use these paint additives and expert painting tricks to ensure a successful job.
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A major room remodel can be stressful, but painting should be the least of your worries. However, with so many options in the stores, knowing which products are best for the job can get confusing. On some walls, for example, you might need a paint additive to help control mildew, prevent fire, add insulation, or thin the paint. Certain additives work best for each of these issues, so it's important to know when and how to use them. Before you can begin painting an interior wall, you'll also need trisodium phosphate or TSP. Learn how to use TSP and paint additives with our guide to preparing paint for a professional look.

four open paint cans with paintbrush on top
Credit: Blaine Moats

How to Use Paint Additives

Paint additives enhance the performance of your paint to work best in different areas of your home. Take a look at the most popular additives below, and see which one works best for your room makeover.

  1. Insulating Paint Additive: Insulation powders, such as this Insulating Additive, ($20, Insuladd) can be added to most interior or exterior paints and primers. This additive helps keep your rooms cooler in the summer and warmer in the winter. Keep in mind these additives can reduce the sheen of a paint, so it's best to add them to your primer or your first coat of color.
  2. Mildew Additive for Paint: Mildew can be one of the most stubborn problems for painted areas, specifically around a bathtub or shower. A mildew-inhibiting paint additive, such as Mildewcide Mildew Preventing Additive, ($7, Amazon), will help alleviate this problem.
  3. Fireproofing Paint Additive: One simple step to prevent a fire from spreading from room to room is to paint prep with anti-flame-spread paint additive, like this Hy-Tech Insulating Paint Additive, ($13, Amazon). If a fire starts in one room, the additive will help prevent the flames from spreading to another. Be sure to check before you buy, however, as many of these additives work only with flat paint.
  4. Paint Thinner: Thinners are a paint solvent that changes the thickness of your paint. They are used often in big paint jobs, which might require a paint sprayer instead of a brush. In that case, you need the paint to be thinner so it can move freely through the sprayer. Paint thinner, such as Klean-Strip Paint Thinner, ($9, The Home Depot) can also be used as a paint cleaner by removing dried paint from your tools and workspace.
scrubbing wall with orange sponge
Credit: Jason Donnelly

What Is TSP?

Trisodium phosphate, or TSP, is a powder you mix with warm water and use to wipe down your walls before painting. It is essential to paint preparation, acting in three ways to improve your paint's adhesiveness.

How to Use TSP to Clean Walls

Most of us don't think that our walls are dusty or even dirty, but if they aren't clean and dry before painting, the paint won't stick properly. To clean walls with TSP, mix the powder into a bucket of warm water until it's completely dissolved (be sure to wear rubber gloves and goggles for protection). Dip a sponge into the TSP solution and use it to wipe down walls. Rinse the surface with clear water and let dry before painting.

How to Use TSP as a Degreaser

TSP also helps to remove stubborn greasy areas. It is crucial to use when painting walls in your kitchen, specifically ones that are near your stove. Any grease that isn't removed before painting can adversely affect the paint's adherence.

How to Use TSP as a Deglosser

When a wall has been painted with a high-sheen paint (satin, semigloss, or high gloss), you need to remove or "dull" that sheen before applying another coat of paint. Otherwise, the slipperiness of the paint below won't allow the next coat to stick, and your new paint will crack. Sanding and proper preparation of the surface is a must, and wiping the area with a solution of TSP and water will help break down a bit of the glossiness of the previous coat. Be aware that TSP will darken some wood, such as mahogany. Use eye protection and gloves when applying and simply "wash" your painting surface with your TSP and water solution, then rinse with a clean, damp sponge.

Always be sure to completely rinse TSP from the walls (and let the walls dry) before you paint; otherwise, the new paint won't adhere properly. Rinse the solution with a clean, damp sponge and you should end up with a beautiful paint job.

room with window prepped for painting
Credit: Marty Baldwin

How to Prep Walls for Paint

Now that your paint has been prepped and is ready for the walls, make sure your room is ready for the paint. This prep process could include repairing any cracks or damage and sanding the wall's surface smooth. Next, you'll need to lay down drop cloths, set up a safe workstation, and tape off any areas of the ceiling or trim you don't want to paint. If you follow these paint prep tips, your room will look professionally redesigned.


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