Field Marking Paints:
Characteristics and Composition
by Mark A. Whitlam
DEFINITION OF PAINT
Paint (1) Verb. To apply a thin layer of a coating to a substrate by brush, spray, roller, immersion, or any other
suitable means. (2) Noun. Any pigmented liquid, liquefiable, or mastic composition designed for application to a
substrate in a thin layer which is converted to an opaque solid film after application. Used for protection,
decoration or identification, or to serve some functional purpose such as filling or concealing surface
irregularities, the modification of light and heat radiation characteristics, etc.
INTRODUCTION TO FIELD MARKING PAINTS
Field Marking has come a long way from the days of lime, chalks and oil based paints used to mark the lines on
sports fields. Today, painting with latex based field paints has become the choice method for lining and decorating
fields. The use of latex paints has a distinct advantage over its predecessors, being safe for the environment,
non-damaging to the turf, having relatively low cost per application, and being easy to clean up.
Today's field marking paints are derived from a mixture of a vehicle, the liquid portion of the paint, and pigments,
the solid portion of the paint. Within each of these segments, the paint derives its own characteristics. In field
marking paints the vehicle contains three primary ingredients -- Included in the vehicle is the solvent (water), the
binder (latex resin), and wetting or dispersing agents (the same liquids used in dish soap). The pigments include
Titanium Dioxide (the whitest pigment available) used as a primary pigment and filler pigments such as Calcium
Carbonates, Silicates, Talc, and Kaolin (clay). All of these materials are combined and ground to form a coating
desirable for the decoration or identification of the boundaries.
Latex has become the binder most used in field marking paints due to its unique structure and ability to be
reduced with water. Once latex has dried, it forms a complex polymer structure of lattices (hence latex) much like
lattice work in construction. However, these lattices build layer upon layer in all directions to produce a paint film.
This allows the substrate, in this case the grass, the ability to "breathe". More descriptive, the distance within
these lattices allows for oxygen and carbon dioxide interaction. This structure also allows for evaporation of very
small water molecules leaving the blade of grass, fueling the grass for continued growth.
Pigments give the paint its color and are generally organic in nature when it comes to field marking paints.
Nontoxic organic pigments have been used since man first began drawing on cave walls over 15,000 years ago.
Organic pigments or pigment colors, however, have changed significantly in the past 100 years. Only recently
have organic pigments been utilized as much as they are today. One reason for the lack of use for organics was
its relatively high cost compared with leaded pigments. Today, organic pigments can now be synthetically
manufactured, offering the user stronger tint strengths, better lightfastness (ability to keep its color), and in a few
cases, new pigment types or color shades allowing for a larger range of colors. With these recent advancements,
organics have offered increased value in their use.
Lead based pigments are still used in some field and marking paints even today. You should avoid using lead
based pigments in any type of paint due to its toxicity and its ability to be absorbed through the skin. Leaded
pigments used in turf paints can also leach from the grass causing ground contamination. Leaded pigments are
commonly found in traffic yellows using chrome yellow pigments, greens using chrome green or chromium oxide
pigments, reds using red lead, and oranges using chrome orange pigments or "moly orange" (molybdate orange).
Be sure to review the material safety data sheets to see whether the paints you are using contain any of these
products.
Titanium Dioxide is the choice pigment when it comes to white paints. Titanium Dioxide has the greatest hiding
ability and also has the highest level of brightness than any pigment know. Titanium Dioxide is used in everything
from plastics to toothpaste. How do you think your teeth get so white? Titanium Dioxide is rarely ever used as the
single pigment in a paint coating due to its high cost and very small particle size. Filler pigments are used to
reduce the cost and fill in the gaps between the Titanium particles. The use of filler or more commonly known,
extender pigments, gives the paint better hiding ability and better reflectance. For example, if you had a jar half
full of large marbles (filler or extender pigments) and added smaller marbles (Titanium Dioxide pigments) and
mixed them together, the smaller marbles, when properly dispersed, would fill in the gaps to produce tighter
grouping - allowing very little light to pass through.
In field marking paints it is desirable to use larger particle-sized extender pigments in combination with Titanium
Dioxide to produce better reflectance and light scatter. This gives the paint coating a flat appearance and allows
the light reflecting off the surface to scatter in all directions.
If you were to look at a flat coating under an electron microscope, it would give you an impression of looking down
at the snow-covered mountains with its many peaks and valleys. These extender pigments or larger particle sizes
form peaks and the smaller Titanium Dioxide particles fill in the valleys, giving the paint its reflectance value and
hiding ability. This type of hiding is desirable for both low angle viewing and optimum reflectance under artificial
lighting.
Surfactants or "wetting agents" and dispersants are the smallest part of field marking paints. Typically only 1-2%
of the total paint consist of these agents. Surfactants and dispersing agents get their name from how they
perform. Surfactants are "surface active agents." Most dry pigments are "hydrophobic" in nature, meaning they
fear water. Therefore, these surfactants allow the latex and water to combine with the pigments and stay "wet" in
solution. Depending on its nature, surfactants will also aid in the wetting of the substrate or grass. The dispersing
agents keep all the ingredients mentioned above in solution and prevent settling out.
PAINTING ON MULTI-PURPOSE FIELDS
Permanent paint on the turf presents a problem to turf managers when their field is used for several different
sporting events. The only available way to remove the paint is to wait for the lines and logos to wear out or use
the old standby, chalk. Several years ago, Whitlam Paint Company with the assistance of David Frey, former Field
Director of Cleveland Stadium, developed a temporary field marking paint named Temp-Stripe for multi-purpose
natural turf fields. The idea was to produce a paint that could be applied like normal field marking paints, but
could easily be removed from the field with the use of minimal water pressure. One concern and probably the
most critical, was how the temporary paint would hold up to foul weather -- and what better place to test it than at
Cleveland Stadium, being known for its harsh and extreme weather? The paint proved effective and held through
three days of rain prior to the event. When it came time to remove the paint from the field, water pressure was
applied with a spray hose hooked to the sprinkler system and a light brush with a broom removed the paint quickly
and effectively. With this type of development, turf managers can now change a field over from football to
baseball or football to soccer without having unsightly lines and logos cluttering up the field.
No longer can field marking paints be considered a paint company's scrap or reworked material. The manufacture
and use of field marking paints has changed and advanced considerably in the past several years. Field marking
paints have become more technologically advanced to provide for easier application, brighter, cleaner colors, and
greater compatibility with the environment.