how to thin oil based paint for a sprayer

Oil-based paints have many advantages and are popular for exterior work and adding additional protective layers to your walls and surfaces. However, oil-based paints present their own set of problems when using an HVLP (High Volume Low Pressure) spray gun. This is because oil-based paints are thicker than latex paint, and you have to thin oil based paint before usage.

In this guide, we look at how to thin oil-based paint for a sprayer as this is something not everyone will know how to do. It is a relatively simple process but it is important that you get it right, and understand the basic steps involved.

How to Thin Oil-Based Paint

Thinning oil paint for spray gun usage is necessary. If you do not thin your oil-based paints, they will not flow freely, and the consistency will be too thick to spray effectively. This could damage your spray gun, and result in a poor finish.

Luckily, thinning oil-based paint is quite easy and once you understand the basic process, you will be able to thin your paints effectively in no time at all. To help, we have compiled a simple 5-step process to thin oil-based paint.

Step 1: Research and Check Your Spray Gun and Paint

Before you do anything, it is vital that you check both your spray gun and the paint. Firstly, not all spray guns are capable of utilising oil-based paints – even when thinned. We always advise checking the instructions or visiting the manufacturer’s website so you have a clear understanding of the capabilities of your spray gun. Make sure it is a good fit for using oil paints, and that it will properly spray the paint once thinned.

Secondly, you must check your paint to make sure it can be thinned. Virtually all paint manufacturers include detailed instructions on the paint can that state how it can be used. In most instances, this will also include thinning instructions and the correct ratios to use. Make sure you read these instructions thoroughly, so you don’t utilise too much thinning agent, and you use the paint properly. Also, we advise checking the drying time so you know how quickly you need to mix the paint and use your HVLP spray gun.

Step 2: Gather the Necessary Equipment

Once you are clear on the instructions, the capabilities of your paint spray gun, and the suitability of the pair for spraying, you can gather the required equipment. Luckily, this list is relatively short. Also, some of the items can be used multiple times. However, some items do need replacing, or cleaning:

  • A strainer
  • Clean stirring sticks
  • A funnel
  • Mineral spirits, or turpentine
  • A clean tin or bucket

When spraying paint, a strainer is an essential item. These are small disposable paper cones – similar to filters used in coffee machines. Strainers are used to filter and purify the paint before you mix it with thinning agents. Regardless of how well spray paint has been initially mixed by the manufacturer, debris and clogging can occur which is why a strainer is important.

Stirring sticks are obviously necessary, too. You can buy packs of reusable or washable paint stirrers from DIY stores. Alternatively, you can use any clean object to stir. However, it must be clean and free of debris. You don’t want to add unnecessary contamination to the paint.

A clean plastic funnel is also important for mixing and pouring the paint. Ideally, this should have a smooth surface that will allow the paint to run quickly. You will also need either turpentine or mineral spirits. These have dual usage. Firstly, they are the thinning agent for the paint. Secondly, they can also be used as a cleaning agent for your equipment after you have thinned the paint.

Finally, if you need to thin paint, you will also require a large container to mix the solution in. This paint container should be large enough for how much paint thinner you want to use. Also, it must be clean! Make sure you clean the paint container thoroughly beforehand, otherwise you could contaminate the oil-based paint.

Step 3: Pour the Paint Into a Clean Container

Once you have your painting equipment, you must pour the oil-based paint into your container. This is where you use the strainer. Don’t pour the paint directly into the container or get any mess. You must ensure to pour it through the strainer to remove any impurities that have gathered inside the paint tin.

Step 4: Mix With Turpentine or Mineral Spirits

measuring mineral spirit Once the oil-based paint is inside the container, you can add the thinning agent. When thinning oil-based paint, the ideal thinning ratio is a 1 part thinning agent for every three parts of paint. The paint-to-thinner ratio is incredibly important to gain the correct consistency.

Luckily, this is something you can adjust and you don’t have to get it right on the first attempt. It is always advisable to add a little mineral spirit or turpentine each time. This way, you can check if the paint is thin enough, and make sure you have not added too much.

Once you have included the thinner or mineral spirits, stir the oil-based paint and thinning agent until they are fully mixed. This is also important and may take time. If you do not mix the thinner and oil-based paint properly, the consistency will be wrong. Plus, you may not be able to use your HVLP paint sprayer effectively.

Step 5: Check the Consistency and Repeat If Necessary

After the thinned paint is mixed perfectly, you can check the consistency to see if it is done properly and if the paint is too thick.

This is where you use the funnel. Run your thinned paint through the funnel and see how it runs. If the paint runs freely, then you have achieved the right thinning consistency and it is ready to use in your HVLP spray guns.

However, if the oil-based paint looks thick on the surface, or it does not have a good flow, you may need to add more thinner or mineral spirits and repeat step 4. This is where caution is required, and it is better to add a little thinner or mineral spirits each time and pass the oil-based paint through the funnel. Using this method and continually repeating steps 4 and 5 ensures you use enough paint thinner, and you thin the paint effectively.

When you are happy with the consistency and flow, you can add your mixture to your paint sprayer and start working!

Tips for Using Oil-Based Paint

You should now have a clear idea of how to thin paint for spray gun usage. To help further, we have provided some general tips when using thin oil-based substances, and for employing other types of paint like latex paint and water-based paints:

1. Always strain your paints for use in an HVLP spray gun.

Straining any type of paint – whether it is latex paints or oil paints, is incredibly important. When the paint is stored in a tin for any amount of time, it can gather impurities. You may notice these impurities on the surface, for example. Also, when the paint is sat, the different chemicals and materials inside can sometimes separate. By straining the paint first, you can remove these impurities and ensure the initial paint is mixed properly.

2. Make sure your equipment and containers are clean before usage.

When using paint, or paint spray, working in a clean environment is important. Firstly, using dirty containers can lead to contamination and it can damage the quality of your paint, plus the surface you apply it to. Secondly, it can discolour the paint. For example, you may unwittingly add used paint into the mixture and cause a colour reaction. Therefore, using clean equipment is important.

3. Always wear protective equipment when using paint with a spray gun.

When using an HVLP spray gun, we advise using protective equipment. Spray painting obviously releases paint particles and paint dust into the air. You can easily breathe this mist in whilst painting and it can cause damage to your lungs. Therefore, always wear a protective mask when using a paint sprayer.

Also, some paints can cause irritation to your skin and eyes. Hence, we always advise wearing protective gloves when using thinner and mixing your paints. This can help prevent damage to your skin, and also ensure you don’t get paint everywhere on your hands, etc.

Oil-Based Paint vs Latex Paint

Finally, let’s take a brief look at latex paint and oil paint and how they compare. It is important to understand the difference between these types so you know the appropriate situations to use them.

In terms of chemical make-up, latex paint is water-based. The other type of water-based paint is acrylic paint. Alternatively, as the name suggests, oil paint is based on oil, not water. This basic chemical distinction dictates the appropriate usage and results.

Benefits of Oil Paints

Oil paints have a range of advantages, especially if you use an HVLP spray gun. The main benefits are as follows:

  • More vibrant, richer colours
  • Increased durability
  • Improved resistance to heat
  • Can cover stains without bleed-through

When using oil-based paint, whether, spraying or via a brush, you will first notice that it offers richer colours. Also, for exteriors, the chemical make-up of this form of paint makes it incredibly durable. It is the best stain-resistant paint and the best paint for spraying external walls. Also, even when used with a thinner, it has great heat resistance.

Generally, this type of paint is also easier to use with spray guns and for spraying larger areas. The downside, however, is that you may find the cleanup process more difficult. It is thicker than latex paint and, therefore, requires more effort to clean if you get it everywhere.

Benefits of Latex Paints

Latex paint is also highly useful but in different situations. Generally, latex paint is better suited for interior walls and ceilings of properties. It offers the following benefits:

  • Cheaper
  • Has a much quicker drying time
  • Easier to clean up

Generally, latex paints are cheaper than their oil counterpart. This is mainly due to the water and lack of oil. Also, this water-based paint has a much quicker drying time. Again, this is because of the water and viscosity of the paint.

When applying thin latex paint, you will also find it is easier to clean. If you get some on an unwanted surface by accident, it can be easily wiped away. This paint is usually better for interiors, in particular, painting ceilings and internal walls.

Oil-Based Paint FAQs

Can oil paint cause harm?

As with most types of paint, oil-based paints can cause irritation if it gets onto your skin. Also, it can be harmful if swallowed and in some instances, the fumes can be dangerous for your lungs. Always take care and wear protective equipment when working with any paint sprayers.

Can you use oil paint in any type of paint sprayer?

Not necessarily. Even when thinned, some paint sprayers cannot spray oil paint. Always check the instructions to see what type of paints you can use with a sprayer.

Let’s Get Started!

Working with paints can be quite a tricky process, especially when you want them for painting with a sprayer. It’s a good idea to research the paints and spray gun that you plan to use. Paint for spraying needs to be thinned exactly right to not only flow through the nozzle but to also have a flawless finish.

If you’re planning to use a tool other than a brush, it is important to know how to thin oil-based paint for a sprayer and how to get the best results. We hope this guide has been useful for your future DIY painting projects. Good luck!


  1. Hi..
    good information posted by you. This information is very useful/helpful for me.

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