How to Thin Oil-Based Paint for Spray Gun


Last updated: April 7, 2023

Learn how to thin oil-based paints for spray gun with this easy-to-follow guide.

Thinning oil-based paint before using it in a spray gun can make all the difference in the quality of your paint job.

That said, do you know how to thin oil-based paint for spray gun? Don’t worry if you’re uncertain; we’ve got you covered.

In this article, we’ll walk you through the step-by-step process of thinning oil-based paint for a spray gun. We’ll also provide valuable information on safety precautions to keep in mind and much more.

Let’s get thinning!

How to thin oil-based paint for spray gun

  1. Pour three parts of oil- based paint into a large bucket
  2. Add 1 part turpentine into the paint
  3. Stir the paint and thinner to mix well
  4. Test the paint’s consistency using a viscosity cup
  5. Add more thinner if necessary

What is Oil-Based Paint?

Oil-based paint, also known as alkyd paint, is made with an oil-based binder (such as linseed oil or alkyd resin) instead of a water-based binder (such as acrylic or latex paint).

Oil-based paints are known for their durability, pungent odor, and slow drying time. They are commonly used for wood, metal, and masonry surfaces, as well as for painting furniture and cabinetry.

They also tend to have higher VOC (volatile organic compounds) content than water-based paint. 

Why Should I Use Oil-Based Paint?

Oil-based paints offer several advantages to your surfaces, unlike any other type of paint. 

The first reason you should use oil-based paint is its ability to protect surfaces against damage from erratic outdoor weather. Most oil paints have UV-resistance properties to protect the surface from fading.

Oil-based paints will also prevent the growth of mold and mildew, thanks to their waterproof feature. This is particularly useful on surfaces that experience high humidity and dampness, like bathrooms and deck sidings.

Using oil-based paints will keep the stains from bleeding through the surface of the new paint. This is particularly useful for outdoor furniture made of wood with high natural oil or resin content.

In addition, oil-based paints are more durable against wear and tear or heavy traffic. They also offer various colors and sheen levels to suit every need.

Should Oil-Based Paint Be Thinned Before Use?

Yes, it’s essential to thin oil-based paints before use if you want to achieve a smooth finish and easy application. 

Oil-based paints are thicker than water-based paints; therefore, thinning it will reduce their viscosity and make them easy to use with different paint applicators.

However, it is important to check the manufacturer’s instructions because different types of paint’ have varying consistencies depending on the brand. For instance, some oil-based paints are ready to use without thinning. 

Safety Tips When Thinning Oil-Based Paints

When thinning oil-based paints, it is important to follow certain safety precautions to protect yourself and the environment. Here’s what we recommend you pay attention to:

  • Wear protective gear: Always wear gloves, googles, and a respirator mask when working with oil based paints and thinners. The fumes and vapors can be harmful to your health.
  • Work in a well-ventilated area to reduce the risk of inhaling toxic fumes.
  • Always read and follow the manufacture’s instructions for the paint and thinner you are using. This helps avoid messing up with the thinning ration and eventual wastage of the products.
  • Keep a fire extinguisher nearby in case of emergency because oil-based paints and thinners are flammable. Also, use these products away from open flames or a heat source.
  • Store the materials properly: Keep paint and thinner in a safe, secure place, out of the reach of children and pets.
  • Dispose of materials safely: Never pour paint or thinner down the drain or into the soil. Dispose of them according to the manufacture’s instructions and local regulations in your region.
  • Clean up any spills immediately and dispose of any rags used with oil-based paint or thinner in a metal container with a tight-fitting lid. Leaving them unattended can lead to spontaneous combustion and fire accidents.

How To Thin Oil-Based Paint For Spraying

Now that you know the importance of thinning oil-based paints and the safety precautions to mind during the process, we can start thinning.

Follow this detailed procedure for thinning oil-based paint to ensure you have the correct consistency for spraying. 

Supplies you will need

    • Clean container
    • Funnel
    • Gloves
    • Mask
    • Paint filler
    • Oil – based paint
    • Turpentine or mineral spirits
    • Clean stir sticks

    Step-By-Step Thinning Procedure

    Once you have all the supplies within reach, ensure you work outside or in a well-ventilated space. Also, wear gloves and respirator masks before opening the paint can or thinner.

    1. Pour the Paint Into a Large Bucket.

    Use a clean stir stick to start mixing the paint using circular or figure-8 motions. This ensures you loosen any paint lumps that may have settled at the bottom.

    Keep stirring until the paint’s pigment distributes evenly and the consistency is creamy-smooth.

    Next, pour the paint into the large bucket through a paint filter. This filter will trap any paint lumps you may have missed during the mixing process. 

    Only pour the amount of paint needed for the size of your project.

    2. Add the Right Amount of Paint Thinner.

    The popular paint thinners for oil-based paints are turpentine and mineral spirits. These are petroleum distillates. In this case, you will need one of the thinning agents, whichever is most accessible.

    Typically, the manufacturer will recommend a specific thinning ratio, but the standard is 1:3. One part thinner to three parts of the oil-based paint.

    Slowly add the thinner to the thick paint in the bucket. Only use the recommended amount first to avoid over-thinning the paint.

    3. Stir to Mix Well.

    Use a clean stir stick to mix the paint with the thinner. Stir the products in the bucket in whichever motion, provided it ensures the paint mixes well with the thinner.

    You can also utilize a drill bit attachment with a paint stirrer to do the job quickly and effectively.

    4. Check the Paint’s Consistency.

    Checking the paint’s consistency will tell you if the paint is already thin enough for spraying or not.

    The best way to establish the newfound consistency is to use a paint flow tester or a viscosity cup. The paint should have the same consistency as heavy cream.

    If the paint flows easily through the cup, it’s ready for use. However, add more paint thinner if the paint struggles to go through the viscosity cup. 

    5. Add More Thinner if Necessary

    If the paint is too thick, continue to add thinner while stirring the paint until you achieve the desired consistency. Check the paint consistency with the viscosity cup; if it flows correctly, transfer the paint to your spray gun.

    Test the paint by spraying it on a cardboard box or an inconspicuous part of the surface to check the flow and atomization. You’re ready for your spray paint job if you like the results.

    How to Thin Oil-Based Paint for Spray Gun

    Thinning Oil-Based Paints Based On The Type of paint Sprayer

    Different paint sprayers require different paint viscosity for efficient results. Some sprayers can spray paint without thinning, while other spray guns need thinned paint for them to function well. 

    Keep reading.

    How To Thin Oil-Based Spray Paint For HVLP Spray Gun

    HVLP, high-volume low-pressure gun, is popularly used to spray oil-based paint. This is because this gun expels a high volume of paint at low pressure, ensuring consistent paint coverage.  

    To thin oil paint for an HVLP paint spray gun;

    1. Stir the paint to mix the pigments evenly.

    2. Pour the mixed gallon of paint into a clean container.

    3. Add 10-15 % mineral spirits into the total volume of paint used.

    4. Stir the thinner and paint thoroughly to mix well.

    5. Run the thinned paint through a cone-shaped funnel to check its consistency. Add more mineral spirits thinner if the paint is still too thick.

    Thinning Oil-Based Paint For LVLP Spray Gun

    Low-volume, low-pressure (LVLP) spray guns can apply oil paints to your target surfaces. However, you will need to thin the paint first to avoid clogging the nozzle tip of the sprayer. 

    To get it done:

    1. Stir three parts of the paint to mix well and filter it into a clean bucket.

    2. Add 1 part of turpentine to the paint and stir to mix well. Keep stirring the mixture until the paint feels thinner.

    3. Pour the paint through the paint flow tester to check if you’ve achieved the consistency needed for an LVLP sprayer. The paint should flow easily and evenly.

    4. If the paint is too thick to flow, add a bit more turpentine, mix well, and test again.

    How To Thin Oil-Based Paint For an Airless Paint Sprayer

    An airless spray gun can spray thick oil-based paints without thinning. However, different paint brands vary in viscosity. 

    Therefore, check the manufacturer’s instructions for the specific paint you use. You’ll find out if they recommend thinning paint for an airless paint spray gun or if you have the leeway to spray without thinning.

    Also, check the tip size of the airless paint sprayer; a larger tip size requires you to thin the paint a little more than when using a smaller tip size.

    In any case, if you’re using a gallon of oil-based paint, you’ll need to thin it with about 10-15 percent mineral spirits or turpentine. Stir the two products well until you achieve the desired paint consistency.

    How To Thin Oil-Based paint For Compressed Air Sprayers 

    Compressed air sprayers use a turbine system to expel paint from the paint holder to the surface. This sprayer allows you to regulate the pressure at which it discharges the paint.

    The turbine’s proximity to the paint holder can affect the paint’s viscosity. If the turbine is closer, it will make the paint dense and, therefore, have uneven coverage when sprayed. Ensure there’s enough space between the paint holder and the turbine.

    That said, the thinning ratio is 3:1, the same as other sprayers already discussed. 

    1. Always start by stirring the paint in the can to mix well. Once that’s done, transfer the paint into a bigger bucket.

    2. Add corresponding one-part mineral spirits or turpentine into the 3 part paint.

    3. Stir the mixture again until fully mixed. Add more thinner if necessary. 

    4. Test the paint’s thickness using a viscosity cup. If you got the consistency right, transfer the thinned paint into the compressed air sprayer and spray away!

    Why Use Oil-Based Paints in a Spray Gun?

    There are several benefits to using a spray gun to apply oil-based paint compared to other paint applicators.

    • A spray gun allows for mush faster coverage of large surfaces than paintbrush or foam roller. This can save significant time and effort when painting a room or exterior of a house.
    • A spray gun helps you apply oil-based paints to a surface and achieve a more consistent and even finish.
    • A spray gun provides a smoother, more professional-looking paint finish than any paint applicator.
    • By using a spray gun, you can use less paint and get better coverage making it more efficient in terms of coat and time.
    • A spray gun can easily apply oil paint to tight or hard-to-reach areas, such as corners and edges, which can be challenging to paint with a brush or roller.

    How Does Temperature Affect The Paint’s Viscosity?

    Temperature can significantly affect the viscosity, or thickness, of paint.

    High temperatures make the paint thinner and more fluid, while low temperatures make it thicker and more challenging to apply.

    If you were to thin paint under such fluctuating temperatures, you would risk over-thinning or under-thinning the paint and consequently end up with uneven spray paint results.

    Therefore, we recommend storing and using the paints within the temperature range recommended by the manufacturer.

    Pro Tips when Thinning Oil-based Paint for your Spray Gun

    Here are some helpful tips to remember when thinning oil-based paint for a spray gun:

    • Use a thinner designated explicitly for oil-based paints because not all thinners are created equal.
    • Start with a small amount of thinner, 10-15% of the total paint volume, an increase as needed.
    • Mix the paint and thinner together thoroughly to ensure an even consistency throughout the paint.
    • Check the manufature’s recommendations for the specific paint and spray gun to ensure compatibility and proper application.
    • Store, thin, and use the oil-based paint in an area with a temperature range recommended by the manufacturer.
    • Safety: Use proper ventilation when working with oil-based paint, as it produces more fumes than water-based paint. Also, wear appropriate personal protective equipment, such as a respirator mask, eye protection, and gloves.

    FAQs – How To Thin Oil-Based Paint For Spray Gun

    What Ratio Do I Thin Oil-Based Paint For Spraying?

    Use a standard thinning ratio of three parts oil-based paint to one part thinner (3:1). Stir the products to mix well and gradually add more turpentine, if necessary. Remember that it’s easier to add more thinner to reduce the paint’s viscosity than it is to add more paint to increase the thickness.

    What Happens if The Paint is Too Thick For Spraying?

    If the paint is too thick for spraying, it will clog up the nozzle tip and cause uneven spray paint results. A highly viscous paint will land on the substrate in thick spurts. As a result, the painted surface will have lumps or ridges and an orange-peel finish. 

    Can You Run Oil-Based Paint Through a Spray Gun?

    You can run oil-based paint through a spray gun after thinning it to the desired consistency. However, some paint brands and spray guns—like the airless sprayer—can spray the paint without thinning. Always check the manufacturer’s instructions to establish paint and spray gun compatibility.

    What Can I Use To Thin Oil-Based Paint?

    You can use thinning agents for oil paints like turpentine or mineral spirits. Both products have their respective odorless substitutes: turpenoid and odorless mineral spirits. These thinners also help you clean up oil paint spills, and applicators like brushes, rollers, and spray guns.

    How Do You Make Paint Thinner For a Spray Gun?

    Begin by combining one part mineral spirits or turpentine with three parts oil-based paint or half cup of water with one gallon of water-based paint. Stir to mix well. Check the consistency by running the paint through a viscosity cup. If it flows easily, the paint is thin enough for spraying.

    Can You Use Vinegar as Oil Paint Thinner?

    Yes, you can use distilled white vinegar as an oil paint thinner in a (¾:1) ratio. That is, for every gallon of oil paint, add three-quarter cup of white vinegar. For best results, gradually add the vinegar to the paint in quarters as you stir. Let the mixture sit for 5 minutes after each quarter.

    What Happens When You Thin Oil Paint Too Much?

    When you thin oil paint too much, the paint will become runny and drip all over the surface when applied. This is because the oil in the binder is over-diluted, creating weaker bonds that won’t stick to a surface. You will also notice a pale, chalk-like pigment when you apply the paint. 

    Final Thoughts On Thinning Oil-Based Paint For Spray Gun

    We hope you’ve enjoyed our article on how to thin oil-based paint for spray gun. 

    The oil paint thinning process is a walk in the park once you know the right thinning agent to use and the correct thinning ratio. Remember to practice safety precautions when handling oil-based paints.

    Now that you know the drill, it’s time to give it a try. Gather your paint, thinner and spray gun and prepare to create something spectacular.

    Have fun painting!

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