Paint thinner is a broad term that actually refers to a range of solvents that are designed to thin paint or remove paint from brushes, rollers, and other painting tools. Common examples of paint thinners include turpentine, acetone, naphtha, toluene, and xylene.
These powerful solvents break down oil-based paints, primers, and stains, making it easier to strip paint off of a surface or clean painting tools. However, paint thinner can also be used to thin the paint by reducing the viscosity of the product for the purpose of filling a paint sprayer or achieving a different finish on a painting project.
Most paint thinner products contain powerful chemicals that can be hazardous to the user's nose, mouth, throat, lungs, and eyes. Paint thinner is also typically corrosive and harmful to your skin, so it's important to always work in a well-ventilated space with the appropriate safety equipment. This should include breathing protection, gloves, a long-sleeve shirt, long pants, closed-toe shoes, and safety goggles with a rubber seal to prevent eye irritation.
How to Use Paint Thinner to Clean Painting Tools
Fill a Container With Paint Thinner
Get a bucket or small container to hold the paint thinner so that it's easy to dip paintbrushes, paint rollers, and rags. Do not use a plastic container, because the paint thinner may destroy the plastic and leak through the container.
Clean Paintbrushes and Paint Rollers
Place the brushes and rollers into the container with the paint thinner. Make sure that you are wearing appropriate safety gear, including gloves, then grab the paintbrush or roller in order to help wipe away the paint as the paint thinner breaks it down.
Clean the brush and roller with warm, soapy water to remove the paint thinner residue, then rinse and dry the painting tools.
Clean Paint Cans, Paint Trays, and Other Objects
Use a dry cloth or rag to clean up a mess on the sides of paint cans, in the bottom of the paint tray, or on any other objects that are safe for use with paint thinner, but cannot fit inside the container.
How to Use Paint Thinner to Strip Paint
Choose the Correct Paint Thinner for the Material
Different paint thinners are intended for use on certain materials, so it's important to find a paint thinner that's appropriate for the target surface. There are a wide variety of options available including products that are made for hardwood, drywall, aluminum, steel, and more. Select the correct type according to the material.
Apply Paint Thinner
Use an inexpensive paintbrush to apply a thin layer of paint thinner to a small section of the wall, ceiling, or any other surface. Check the manufacturer's directions and allow the paint thinner to sit for the required amount of time. It typically takes about 20 minutes for the paint to soften.
Remove the Paint
After allowing the paint thinner to soften the paint, it should be relatively easy to use a plastic paint scraper to scrape the paint off the surface of the material. If all the paint does not come off with the plastic scraper, you may need to apply additional paint thinner. Just make sure that you don't use too much paint thinner, as it can seep into porous materials, like wood.
Clean off the Paint Thinner
When the paint has been removed, wipe down the area where the paint thinner was applied using clean water and a cloth or rag. This helps to protect the wood or metal surface and prepare it for repainting.
How to Use Paint Thinner to Thin Paint
Choose an Appropriate Paint Thinner
Paint thinners come in different types according to their purpose, so it's necessary to find a paint thinner product that is suitable for the type of paint that you are using. Check the manufacturer's information to ensure that the paint thinner is appropriate for the paint before choosing a product.
Measure and Mix the Paint Thinner
In order to thin the paint, it's necessary to mix the paint thinner with the paint, but if the ratio of paint to paint thinner is incorrect, it could ruin the paint. Typically a 3:1 or 4:1 ratio of paint to paint thinner is suitable for general-purpose paint thinning, like thinning paint to load a paint sprayer, but always refer to the manufacturer's recommendations to get the right mixture.
Combine a small amount of paint and paint thinner to create a test batch. Use four parts paint and one part paint thinner to start and see if this ratio creates the ideal paint viscosity. If necessary, add or reduce the amount of paint thinner until you get the right mix. Once you have the correct ratio, you can mix up a larger amount of paint. Also, make sure to use a suitable container for mixing that won't be damaged by the corrosive properties of the paint thinner.
Test the Mixture
Apply a small amount of paint to the desired surface or load it into a paint sprayer to test the viscosity, appearance, and adhesion. The paint should completely cover the surface and should not run or drip excessively. If the paint still seems too thick, add small amounts of paint thinner and repeat the test until you are satisfied with the results.
Storing Paint Thinner
After using the paint thinner, the container should be sealed and stored in a cool, dry location. Refer to the manufacturer's directions for the ideal storage temperature and consider keeping the paint thinner in a basement workshop, garage, or shed as long as the temperatures inside the storage area do not become too hot during the summer months.
High temperatures can cause the paint thinner to evaporate and put the container at risk of exploding or even catching fire, as paint thinner is typically a flammable substance.
OSHA Infosheet: Toluene Safety in the Workplace. Occupational Safety and Health Administration, U.S. Department of Labor.