In this Guide
How to thin latex paint? The finish results you get from spraying paint depend as much on the thinning work you do as the technique you apply while using your sprayer! It doesn’t matter how careful and consistent you are if your coating material is inconsistent or spraying in an erratic manner. How to thin latex paint?
In this short guide, we’ll talk through everything you need to know about thinning paint. How to thin latex paint? We’ll be discussing both airless and HVLP spray guns, as well as the differences between working with latex vs. oil-based paint.
How to thin different types of paint
Different types of paint will have to be thinned in a specific way according to the specificities of the paint. The main steps are the following
- With a stir stick, take time to stir the paint until it forms a complete homogenous paste, you can stir in circular shapes and adding upward and downward movement to it.
- Pour the paint into a container as you should avoid altering the paint directly from the bucket
- Add a small amount of room temperature water for acrylic paints or paint thinner for oil-based paints
- Mix the paint and added water with a brush.
- You can add water and mix it again if the previous paste was too thick
- Add more water and mix the paint until you get the good thinning.
- Try to apply the thinned paste on a small piece of surface to check whether it has a good consistency.
How to thin latex paint?
Latex paint is the most demanding when it comes to straining. They’re extremely viscous, so whenever you spray them with a handheld, HVLP, or small airless sprayer, you need to thin them down. Thankfully, it’s relatively easy to do. Unlike working with many oil-based paints, you can use plain water to thin latex compounds. Get yourself a measuring cup and a stirrer, and you’re good to go.
How to thin latex paint? At a minimum, you should plan to thin the latex paint by 10%. Another minimum ratio that’s often used is half cup water per gallon of paint. That’s true when you’re using anything other than a big airless unit. If you’re using a handheld or HVLP system to paint, you’re probably going to have to use as much as 20-30% water.
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How to thin oil-based paint?
Oil-based paints (such as semi-gloss enamels) also tend to need some thinning. They’re far less viscous than latex coatings out of the can, but you can achieve a better spray consistency by thinning them down a bit further.
Always read the labels on the specific coatings you’re using to see what the maximum thinning ratio is. Check to see what thinners the manufacturer recommends since you usually have to use some kind of mineral spirits rather than water. You’ll probably only need to thin these by 10% or so, depending on your specific sprayer, coating, and application.
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How to thin acrylic paint?
Acrylic paint is water-based, so in theory, it is very friendly to added water. How to thin acrylic paint? Since it’s water-soluble, though, you can’t add too much water into the acrylic paint. Over-saturated acrylic paint flake or lose its bonding abilities completely. On absorbent surfaces, feel free to use as much as 50% added water in the acrylic paint. If you’re spraying onto something non-absorbent, you should thin acrylic paint up to 30% only. If you thin acrylic over the prescribed limit it might not adhere to the surface you want to paint.
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What is acrylic paint?
Acrylic paint is a type of paint composed, like all the paint, of 4 elements, the binder, pigments, solvent or water, and the additives. The Binder is the basic need of any paint composition. It is an actual film-former in a paint coat. Binders are in form of organic or inorganic compounds of different structures. Pigments are responsible to provide color and opacity to enhance the film’s durability, hardness, and protection from corrosion.
Solvents are organic materials that are miscible with various resins and oil, solvents. For acrylic paint, water is used instead of solvents and is useful to reduce the viscosity.
Additives are added to modify certain desired characteristics e.g fast-drying properties, stability, gloss, etc.
Acrylic paint is named as such because the pigments and additives are mixed with an acrylic polymer emulsion. Acrylic polymer is used because of the properties it gives to the paint.
Here are some properties of most acrylic paint:
- A quick-drying (approx 10min)
- Flexible coating
- Easy to clean with water
- Acrylic paint can stick to almost any surface
- No smell and non-toxic
Let’s head to the section on how to thin your paint for the paint sprayer that you have
How to thin for different types of paint sprayers
These sprayers are designed to work primarily with oil-based paints. You can certainly use them with latex paints for indoor applications, but you’ll have to thin quite a lot. Start with 10% of water, and then work upward until you reach a sprayable consistency. Latex conditioners are also an option. These compounds give the effect of thinning without actually doing so. They decrease viscosity, which helps paint flow more easily without compromising its capacity to stick.
- Use paint conditioner with all latex paints to make application easier with spray or brush or roller.
Any time you use an HVLP system, you should strain materials religiously. It’s a smart thing to do even on an airless system, to prevent any stray globs, but it’s a downright necessity with HVLP. Use a standard cone strainer.
Another tip for spraying using an HVLP system: HVLP turbines add heat to paint. It’s a key downside to the system since it shortens the paint’s drying time (and makes it more viscous in your gun). You can negate that effect by adding a longer length of hose between your turbine and your gun.
Find current reviews of the best HVLP paint sprayers here!
Latex paint is right at home with an airless system. In fact, many airless systems are intended to work without any thinning! You can spray straight from a can or bucket. However, you should know that there are some caveats. We’ve found that the bigger pump systems can spray un-thinned paints without issues, but the smaller indoor units (especially under $500) are best used with thinned materials. You don’t need to go crazy with thinning, though. Less than 20% water content should be more than enough. If you spray oil-based coatings using an airless system (and you rarely would be), you almost certainly don’t need to do any thinning.
To see which airless sprayers we recommend, head over to our buying guide to spraying latex paint!
How to know when the paint is thinned sufficiently?
This is where your viscosity cup comes in handy! You should get one with any good paint sprayer. A viscosity cup is essentially a glorified funnel. To test your thinned paint, you pour the paint through the viscosity cup and check to see that it’s flowing smoothly. If it’s coming in globs or flowing unevenly, it needs to be thinned further. If it drips quickly like water, you’ve thinned too severely and will need to start again or pouring more unthinned paint into the mixture.
Don’t follow any strict proportion when you’re thinning paints
It’s all about what works for you at the moment. Spray consistency depends on any number of things. It’s affected by air pressure, humidity, and the exact spray tip size you’re using on your gun. So, use our recommendations as a rough guide and then adjust based on how your actual spray results come out.
Tweak your proportions gradually, too. If you thin too far, you won’t be able to get coatings to stick properly. You can easily ruin a whole can by adding too much water at a time. Thin gradually and test continually.
Always test your spray on something other than your work surface!
Keep a spare piece of something fairly smooth and similar to things you’d actually paint. Masonite is a good choice. Avoid something rough like plywood, since you won’t be able to judge the consistency of the paint coat with so much surface inconsistency in the first place.
Always use proper safety gear when working with paints of any kind.
Aside from harmless water-based acrylics, all paints are toxic to some extent. They contain chemicals that produce fumes that irritate both lungs and eyes. So, be sure to use an OSHA-approved respirator with a suitable chemical cartridge installed. You’ll also want to wear goggles to protect your eyes while mixing and spraying. Gloves are especially important when working with oil-based coatings, but they also save you from having to scrub latex off.
Be aware that some kinds of paint aren’t meant to be thinned at all.
That’s true of quite a few oil-based materials. If you can’t thin your can, and it doesn’t spray well as is, you’ll need to apply it with a roller or brushes.
You can always change your spray tips!
As important as thinning is, it’s not the only factor that determines how well your coatings will spray. Opting for a larger tip size can also be pragmatic.