How to Mix Automotive Paint With Reducer & Hardener

by Paul Miceli
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Modern automotive paints are activated with hardeners to promote faster drying times. Reducer is added to help the material flow through the spray gun easily. The mixing process is a vitally important aspect of automotive refinishing work. Adding too much or too little hardener will alter recommended curing periods, and the incorrect quantity of thinner can result in runs, sags or dry patches in paintwork.

Step 1

Wipe out the paint mixing pot with a clean piece of cloth to remove traces of dust and other foreign contaminants. Place the paint mixing pot on a flat, even surface. Stand the paint measuring stick against the inside wall so it rests in a vertical position.

Step 2

Stir the automotive paint thoroughly with a disposable stirring stick before mixing begins. Make sure the separate pigments mix together. Check the paint against the vehicle to make sure the color is accurate.

Step 3

Refer to the technical data sheet supplied with the automotive paint to establish the correct mixing ratio. Remember that the mixing ratio is written sequentially. So figures of 2:1:1, for example, will relate to two parts of automotive paint, 1 part of hardener and 1 part of reducer. Check the markings on the paint measuring stick to ensure the correct ratio markings are available.

Step 4

Determine how much unmixed material is needed for painting. Refer to the left-hand side of the paint stirring stick to view the different volume measurements. Note that each numbered vertical marking represents one-tenth of a liter of automotive paint. Add paint up to marking number 1 on the left-hand side of the stick if 100ml of unmixed paint is required. Add up to the number 2 if 200ml of unmixed paint is needed. Add up to any other number that represents the correct volume of material necessary to complete the job.

Step 5

Take a tin of compatible hardener and look at the markings on the center of the paint measuring stick, which represent the second part of the mixing ratio. Fill the paint mixing pot to the same number on the center of the stick as you used when adding unmixed paint. Add to the number 1 if the paint was added to number 1 on the left-hand side; 2 if the paint was added to 2 on the left-hand side; or any other relevant number that matched your original paint quantity.

Step 6

Repeat the process on the right-hand side of the stick with compatible reducer, making sure the pot is filled to the same number on the paint measuring stick so it matches the number used for the unmixed paint and hardener. Allow the material to settle for a few seconds before stirring the three components together and adding the mixed product to a spray gun.

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