How to Mix Paint for Spray Gun?

How to Mix Paint for Spray Gun

You are going to need:

  • Clock or stopwatch
  • Viscosity cup
  • Bucket or spare container of some sort with a large opening on top
  • Water
  • Paint
  • Mixing utensil
  • Respirator

Step 1: Safety first

Paint fumes are not something which should be ignored; ensure you are wearing a respirator before beginning.

Step 2: Research your guide

When we are mixing paint, the universal rule we need to consider is ‘what viscosity do I need?’ With this in mind, we should first consult the manual of our spray gun to see what the viscosity guide tells us for our paint. Lacquers will require less time than primers for instance, every gun is different in terms of what viscosity they need to function best.

Step 3: Measure your initial viscosity

Place your viscosity cup into your paint can and measure how thick the paint is and how long it takes to fully exit the cup.

Step 4: Divide your paint and start to mix

Once you know your initial viscosity, you can separate out a small amount of usually 500ml of paint into your container, starting to add water and mixing.  Always mix for at least 5 minutes. Some choose to use a drill attachment to mix but this isn’t always necessary.

Step 5: Trial and error

After you have started adding water little by little, it’s simply a matter of testing the viscosity of it over and over again. Dipping the cup and starting the clock, once the paint starts to drip you can stop the clock. Repeat this process until your time matches what has been stated as recommended in step 1. Remember to clean your cup between measurements.

How to thin water-based paint for spray gun

All spray guns are different in terms of ratings for paint suitable for use, but in general 20 to 30 seconds is suitable for most water-based paints. When it comes to thinning these paints, you will need the same utensils required for general mixing and thinning as listed previously. When it comes to water-based paints we need to steer clear of using anything other than water to thin the paint. The best process for thinning water-based paint is as follows

Step 1: Equip yourself

Gather safety equipment such as a respirator and put this on, along with gathering your water, two buckets, and a viscosity tester cup along with a stopwatch.

Step 2: Measure viscosity

Simply dip your viscosity test into your initial paint can and start the stopwatch, stopping this when a drip begins. This will most likely be around the 5:30 mark or 6 minutes, in which case you can add more water initially.

Step 3: Begin transferring water and paint

In one of your buckets or spare paint cans, add 400ml of paint followed by 100ml of water. Ensure you pour this slowly and close to the surface of the paint as it will not mix properly if lazily poured in a fast motion.

Step 4: Mix through transferring

Rather than stirring with a paint mixer, best practice for thinning water-based paints is to transfer the paint between two containers, ideally two paint buckets. Transfer the paint between two containers for a minimum of 10 minutes before testing the viscosity.

Step 5: Repeat until ideal viscosity achieved

As mentioned previously, aiming for between 20 and 30 seconds for your viscosity test is the generally agreed time frame for water-based paints.

How to thin enamel paint for spray gun

While water is a great cheap way to thin most paints, enamel paint will not react the same way as others when thinned with water. Accordingly, it’s best to make use of mineral spirits or a more commercial form of paint thinner or conditioner. However, because of this, you will need to ensure you are in a well-ventilated area with appropriate safety equipment. These thinners have the additional benefit of minimising drying time when spraying. Accordingly, you will need the following for thinning enamel paint:

  • Mineral spirits
  • Lacquer thinner
  • Viscosity cup
  • Respirator
  • Stopwatch
  • Paint stirrer
  • Two buckets
  • Gloves
  • Paint

Step 1: Safety measures

Equip your respirator and some gloves, making sure you are also in a well-ventilated shaded area out of direct sunlight.

Step 2: Pour thinning mixture

Start by pouring equal parts mineral spirits and lacquer thinner into their own bucket, for a total of 300ml of liquid. This will be used for determining the correct amount for thinning your paint, with the required ratio to be applied to the rest of your paint. Ensure you don’t pour too much.

Step 3: Pour paint and test viscosity

In a separate bucket, pour 400ml of your paint, testing the initial viscosity from the paint can while you do this. You should notice the initial viscosity exceeds 5 minutes. Test the viscosity by dipping your viscosity test cup in your paint and starting your stopwatch. Once the paint is a drip from the bottom, stop and record the time on the stopwatch.

Step 4: Begin adding the thinning mixture

Ensure you are careful when adding in small amounts of your thinning liquid to your paint. You should be adding around 150ml initially then 20ml each time afterward.

Step 5: Test until correct viscosity achieved

In between tests, ensure you are cleaning the cup in warm water, making sure there are no leftover specks of paint on the test. You will know the viscosity is at the ideal level when the test takes around 25 seconds.

If you are using the paint for shading, you will want to use a heavier mix of thinner rather than paint. Usually, a 50/50 mix of paint and thinner works for most applications, but consult your spray gun manual for exact specifications.

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