Auto Paint Repair

Understanding Car Paint Mixing Ratios


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When it comes to repainting a vehicle, one of the keys to the correct color is the car paint mixing ratio. The ratio sets the color that you see when you look at the vehicle. For example, if your car is a light yellow, then you will need a yellow color. Then you will need to mix  the yellow color with primarily white paint pigment to achieve the correct paint color.

Parts by Volume

The mixing ratio is based on a fixed basis. That fixed basis may be a teaspoon or a 55-gallon drum. Using the fixed basis, you will then be able to establish the mixing ratio of the paint. As an example, let's say that you use a 5-gallon drum and mix in two teaspoons of a color to establish the color of the vehicle.

Two teaspoons are the equivalent of about 1/3 of an ounce of liquid. Now you have 1/3 of an ounce of liquid that is mixed into five gallons of paint. A gallon is 64 ounces, so you are using a five-gallon can of paint and mixing 1/3 of an ounce with 320 ounces (five gallons). This gives you a mixing ratio of .0005709375:1 for the color element and the primary pigment being used. As you can see, this is a pretty small ratio but, nevertheless, it is one that is standard throughout the industry.

Specific Example

This is only one specific example dealing with two teaspoonfuls of color to a five-gallon can of paint. This ratio can change and become much larger as you use larger base colors and pigments.

Another piece to the mixing ratio puzzle is the hardener. It is expressed as the third number in a triad with the form XX: YY: ZZ or base: thinner: hardener.

In our example, the mixing ratio would be 1:00057:00057. These numbers do not vary across the industry, so if a company were to use a ratio of say 6:2:3, you would know that the paint contains a mixing ratio of six ounces of the base product, two ounces of thinner and three ounces of hardener.

This is not a hard and fast rule either, as there are some paint manufacturers that reverse the hardener and thinner ratios but, by general agreement, the format remains the same.

Some Complication

One thing that does complicate the issue is that this ratio can also be expressed as a percentage. If it is expressed as a percentage, then some simple math is needed to turn the percentage into a fraction and then to plug it into the existing formula.

Say, for example, that one expresses the amount of hardener as 33%. This turns out to be 1/3. This would mean, therefore, that you could have three parts of hardener or thinner to six ounces of base. It's actually not hard to figure out and it does give some uniformity to paint. This uniformity enables shops all over the country to determine the paint formulation needed for a specific car once they have determined the basis used by the paint manufacturer.

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