Mixing Ratio Reference Materials

Overview

Mixing ratios can be stated either in parts or percentages, parts (normally by volume) being the most commonly used and easiest to understand.

When a mixing ratio is given in parts, the measurement chosen as one part can vary greatly. For example, One teaspoon could be used to measure one part, or one 55 gallon steel drum could be used to measure one part. Regardless of size, the chosen measurement must remain the same throughout the mixing process. A mixing ratio given as 4:2:1 normally means 4 parts of base product, 2 parts thinner/reducer, and 1 part hardener. However, some paint manufactures add hardener second, and thinner/reducer last.

When a mixing ratio is given as a percentage, convert the percentage to a fraction, then think of the fraction as parts solvent/parts paint.Examples of this type of mixing ratio is best illustrated below on the Reduction Recommendations Chart. For instance, the 33% listed in the chart would be 1/3 or one part solvent (thinner/reducer) to three parts paint.

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Reduction Recommendations Chart

PERCENTAGE FRACTION AMOUNT OF THINNER / REDUCER AMOUNT OF PAINT
25% 1/4 1 part 4 part
33% 1/3 1 part 3 part
50% 1/2 1 part 2 part
75% 3/4 3 part 4 part
100% 1/1 1 part 1 part
125% 5/4 5 part 4 part
150% 3/2 3 part 2 part
200% 2/1 2 part 1 part

Reduction percentages can become confusing. Areas where problems may arise include the following:

  • 50-50 may mean 50% to the painter, but in reality is 1 to 1 or 100% reduction.
  • 25% solvent 75% paint may mean 25% reduction to the painter, but is actually 33% - 1 part solvent, 3 parts paint.

The same confusion can occur with the remaining percentages.It must be understood that the volume of unreduced base product is always multiplied by the percentage of reduction to equal the amount of solvent to be added.

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Paint Reduction Equivalent Chart

Percent Reducer or Thinner
 
Percent Paint Reducer or Thinner Paint Reducer or Thinner
12 - 1/2% 8 1 8 oz. 1 oz.
25% 4 1 8 oz. 2 oz.
33 - 1/3% 3 1 8 oz. 2 - 3/5 oz.
40% 5 2 8 oz. 3 - 1/5 oz.
50% 2 1 8 oz. 4 oz.
75% 4 3 8 oz. 6 oz.
100% 1 1 8 oz. 8 oz.
125% 4 5 8 oz. 10 oz.
150% 2 3 8 oz. 12 oz.
200% 1 2 8 oz. 16 oz.
 
12 - 1/2% 8 1 16 oz. 2 oz.
25% 4 1 16 oz. 4 oz.
33 - 1/3% 3 1 16 oz. 5 - 1/3 oz.
40% 5 2 16 oz. 6 - 2/5 oz.
50% 2 1 16 oz. 8 oz.
75% 4 3 16 oz. 12 oz.
100% 1 1 16 oz. 16 oz.
125% 4 5 16 oz. 20 oz.
150% 2 3 16 oz. 24 oz.
200% 1 2 16 oz. 32 oz.
 
12 - 1/2% 8 1 32 oz. 4 oz.
25% 4 1 32 oz. 8 oz.
33 - 1/3% 3 1 32 oz. 10 - 3/5 oz.
40% 5 2 32 oz. 12 - 4/5 oz.
50% 2 1 32 oz. 16 oz.
75% 4 3 32 oz. 24 oz.
100% 1 1 32 oz. 32 oz.
125% 4 5 32 oz. 40 oz.
150% 2 3 32 oz. 48 oz.
200% 1 2 32 oz. 64 oz.
 
12 - 1/2% 8 1 1 gallon 1 pint
25% 4 1 1 gallon 1 quart
33 - 1/3% 3 1 1 gallon 1 - 1/3 quarts
40% 5 2 1 gallon 3 pints
50% 2 1 1 gallon 2 quarts
75% 4 3 1 gallon 3 quarts
100% 1 1 1 gallon 4 quarts
125% 4 5 1 gallon 5 quarts
150% 2 3 1 gallon 6 quarts
200% 1 2 1 gallon 8 quarts

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Measuring and Mixing utilizing a Mixing Stick (Volume)

Assumptions:

  1. The base product has a mixing ratio of 4 : 2 : 1
  2. The container has a flat bottom and parallel sides.
  3. Insert mixing stick into the container and hold vertically.
  4. Pour base product to line below #4 (select graduations that provide the volume of material needed).
  • Insert mixing stick into the container and hold vertically.
  • Pour base product to line below #4 (select graduations that provide the volume of material needed).
  • Add thinner / reducer to line # 6 and then stir.
  • Add hardener to line # 7, and then stir.
Diagram of Measuring and Mixing utilizing a Mixing Stick (Volume)

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Measuring and Mixing utilizing a Graduated Container (Volume)

Assumptions:

  1. The base product has a mixing ratio of 4 : 2 : 1
  2. Using an 8 ounce container graduated in one ounce increments.
  • Pour base product to line 4.
  • Add thinner / reducer to line 6 and then stir.
  • Add hardener to line # 7, and then stir.
Measuring and Mixing utilizing a Graduated Container (Volume)

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