ADDITIVES – ADDITIONAL INGREDIENTS THAT AFFECT AND ENHANCE MANY PAINT PROPERTIES

Below is a list of additives used in the manufacture of latex paints, and a description of how they affect the properties of those paints.

1. Thickeners and Rheology Modifiers
(rheology is the science of how a liquid tends to flow)

• provide adequate viscosity (thickness), so the paint may be applied properly
• impact how thick the paint goes on and how well it flows out when applied
• modern rheology modifiers help latex paints to:
        - resist spattering when applied by roller
        - flow out smoothly
        - be less likely to spoil than with older generation thickeners
          (with spoilage, the paint may smell putrid and/or lose viscosity)

2. Surfactants  (specialized soaps)

• stabilize the paint so that it will not separate or become too thick to use
• keep pigments dispersed for maximum gloss and hiding
• help "wet" the surface being painted, so the paint won't "crawl" (move about)
  when it is applied
• provide compatibility with tinting colorants so that the correct color will be obtained...
  and help assure that it won't change before the paint is used

3. Biocides:  two types are used in latex paints

1. a preservative to keep bacteria from growing in the paint

(This is especially important for paint stored in containers that are repeatedly opened and closed, because contamination can occur.)

2. a mildewcide, to discourage mildew from growing on the surface of the paint after it has been applied.

(This is used mainly in exterior products, although some interior paints, such as those formulated for use in damp areas, e.g., kitchens and baths, may also contain mildewcide.)

4. Defoamers break bubbles as they are formed in the paint when:

• the paint is mixed in the factory
• it is put on the shaker or stirred
• it is applied to the surface (especially important when rolling the paint on)
  
  

5. Co-solvents are additional liquids other than water; that:

• aid the binder in forming a good film when applied down to the minimum recommended application temperature
  
• help the liquid paint resist damage if frozen
  
• enhance brushing properties, including flow and "open time" (the time the paint can be applied and worked, before it sets up)

The co-solvents are generally volatile organic compounds (VOCs).

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