What Is the difference in paint thinners?

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The correct choice of auto paint thinners can make the difference between applying a successful topcoat, and leaving a finish covered in sags or an orange peel texture. Thinners lower the viscosity of paint materials and their solvent composition affects overall drying times.

However, professional paint sprayers have a range of additional thinners available that complete different processes. As well as reducing paints, thinners are also used for cleaning guns and completing specialist repairs.

Reducing thinners

Reducing thinners are added to paint at a specified ratio to optimise application and material performance. The thinners reduce the viscosity of the paint so that it flows through the chambers of the spray gun more easily. It also helps to promote the atomisation properties of the diluted material. Many paints use a hardener to speed up the drying process but on metallic basecoats, only reducing thinners are used.

Variable speed thinners

Variable speed thinners are used to reduce the viscosity of the paint and to increase or decrease the drying times. Slow speed thinners delay the drying process and are largely used on large paint jobs such as commercial vehicles or repaints to prevent dry finishes. Medium speed thinners can be used when the drying time needs to be increased slightly, and is most commonly used when the side of a vehicle is being refinished. Fast thinners can be used for single panel paint jobs and they dry very quickly. This makes them ideal for bodyworks garages where fast turnaround times are required. Variable speed thinners only increase drying times when used in a low-bake oven.


Accelerators are high-speed thinners that promote rapid drying times. They are perfect for single coat paint applications, especially if the vehicle is being left to air dry in a workshop. Accelerators react with paints and hardeners to produce fast drying times in ambient temperatures and are frequently used in workshops where low-bake facilities are unavailable.

Blending thinners

Blending thinners are used on auto body panels where the paint is being faded out over a small area. This helps to reduce the typical paint costs that arise from refinishing an entire panel. Paint is usually applied over the area, and a light coat of blending thinners is sprayed over the outside edge of the paint to produce an invisible repair.

Cellulose thinners

Also referred to as standard thinners, cellulose thinners are used for cleaning spray guns and mixing pots. Thinners are added to the storage tank of a mechanical gun washing machine and spray guns are placed on nozzles to ensure the chambers are thoroughly cleaned. When the gun washing machine is activated, it completes a timed cycle that sprays thinners over the inside and outside of the gun.