Additives
to Ensure a Smooth, Uniform Finish :
A Quality Tale with
Pictures
| Ever wonder how the ingredients
in the paint can impact performance? Here’s
one way to think about it. Waterbased paints consists
of 4 main
ingredient type as depicted in diagram: |
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The choice of these key
ingredients impacts paint quality and performance.
In this article we wish to
focus on Additives. In particular we want to focus
on thickeners or Rheology Modifiers. Rheology Modifiers
impact how thick the paint goes on and how well
it flows out when applied. Rheology Modifiers also impact
the durability and resistance of the finished paint film.
Today’s quality paints utilize more modern synthetic
thickeners which allow formulators to tune key properties
like:
• Flow
•
Sag
•
Film Build or Film Thickness (resulting in improved
hiding)
•
Creaminess and Smoothness
•
Feel and Transfer to Application Tool
•
Water Resistance
Flow: With a latex paint, how can you paint a trim
or door or cabinet and get an acceptable smooth finish
(free of brush marks) with the desired sheen?
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Today’s quality latex paints use modern
associative thickeners to deliver excellent flow!
The better flow not only delivers the desired smoothness
and gloss, but leads to better coverage or hiding
as the paint is spread more evenly. The coating
on the left clearly hides the black and white substrate
much better than the poorer flow finish on the
right.
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In fact, today’s Top Quality
100% Acrylic Latex paints can deliver flow similar
to traditional oil based alkyd enamel paints.
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Sag: A paint formulated at
ideal viscosity gives the desired flow to cover with
the appropriate film thickness,
look and overall smoothness without compromising
sag. That is, it provides a paint film with no
undesirable vertical drips as shown below. As you can
imagine getting
the appropriate flow and sag balance for multiple
application methods is not trivial. With modern
synthetic
rheology modifiers the paint viscosity can be dialed
in to deliver robust flow-sag performance; however,
one must follow the recommended guidelines (e.g.
spread rate) to best ensure acceptable performance.
For more information on paint spread rates, please
link on link below:
http://www.paintquality.com/contractor/article/cont02_12doc.html
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Spatter: Spatter is the
term for annoying specs and droplets resulting
from the application of a paint to a wall
or ceiling. Todays quality paints resist
spatter resistance! This is enabled by employing
modern synthetic thickeners which provide
an improved cohesive profile and minimize
droplet and spatter formation.
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The picture shows what happens when white
paints are rolled out above a black chart.
The higher density of white specs is evidence
of a paint with poorer spatter resistance.
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Modern synthetic rheology modifiers
afford formulations the opportunity to tune performance
from manufacturing
and storage (minimizing in-can settling) to application
feel (transfer from brush to optimization for spray
application) to final film properties.
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Todays top quality
100% Acrylic Paints utilize modern synthetic
thickeners which, not only provide a final finish
with desirable durability properties, but also
minimize rework and clean-up.
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The Rohm and Haas Paint Quality Institute
P.O. Box 1348
Philadelphia, PA 19109
215.592.3000
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