The short
definition of a polymer floor coating’s pot life is, the amount of time that
the coating material remains in a fluid liquid state, allowing for its proper
application onto a given floor substrate.
As the above
definition indicates, a coating’s pot life is measured in terms of time.
Specifically, it’s the amount of time that elapses from the moment the liquids
are mixed until the moment that the mixture is no longer fluid enough to be
applied to the substrate, as intended. Often, terms which are associated with a
coating’s pot life, will be used interchangeably and, for the person who is new
to the world of coatings or for professionals who may have gotten their
coatings education on the fly, the simple concept of a material’s pot life can
sometimes become unnecessarily murky. So, for the sake of clarity, following
are the practical basics with respect to a polymer coating’s pot life.
A high
performance polymer floor coating will, more often than not, be comprised of
two liquid-state materials, which become the actual coating once they’ve been
combined. The two separate liquids are usually supplied as a unit called a
“kit”. The two components of the kit are usually referred to as parts “A” and
“B”. Most formulating manufacturers refer to the resin portion of the
kit as Part A and the activator as Part B. The activator is also called
a hardener, a curing agent or a catalyst.
When a
predetermined amount of polymer floor coating resin is thoroughly mixed with a
designated amount of its corresponding catalyst (a combination called the mix
ratio), the two react and form three-dimensional crosslinking carbon
molecule bonds throughout the coating’s structure. The crosslinking process
starts as soon as the resin and its hardener are mixed.
As
crosslinking evolves and begins to cure, the coating material’s viscosity
increases. The lower a coating material’s viscosity is, the more fluid it is.
The higher its viscosity, the less fluid and more rigid it will be. As an
example, water has a low viscosity level and maple syrup and Silly Putty both
have higher viscosity levels. The coating material's pot life comes to an end
when proper application of the coating is no longer possible due to a loss of
the material’s fluidity and an increase in its viscosity.
The pot life
of a polymer coating will be influenced (faster or slower) depending on five basic
variables:
- The chemical
formulation of the material.
- Coatings can be
formulated to either increase or decrease pot life and cure times.
- The temperatures of the coating material, application environment and of the substrate.
- Higher temperatures will shorten and lower temperatures will
lengthen a coating’s pot life.
- The ambient
relative humidity.
- An increase
in humidity can increase pot life and a decrease in humidity will decrease pot
life.
- The amount of
materials that are mixed together at one time (volume).
- Greater
amounts of material mixed together at one time will shorten pot life while lower amounts will allow
for a longer pot life.
- The use of
retarders or accelerators.
- These types
of additives can be incorporated into the coating material at the point of mixing and can effectively slow down or speed up the coating material’s pot
life as needed.
Some other terms
that are sometimes used instead of pot life are:
- Application Time
- Open Time
- Pour Time
- Spreadable Life
- Spreadable Time
- Usable Life
- Usable Time
- Wet Time
- Work Time
After a
coating’s pot life has been reached, it passes through three basic curing
stages:
- Gel Time
- This marks the point in a cure when the
mix is incapable of flow.
- Tack Time
- The intermediate point between a coating’s liquid state (wet) and its solid state (cured). During this stage, the coating will feel sticky.
- Cure Time
- This is the amount of time it takes a
coating material to first become tack-free and then to reach a fully cured
state. A floor coating’s full cure will typically be reached over the course of
various days.
If you don’t
already do so, start to make a habit of using both the term and the concept
of pot life when planning a floor coating application. It should be your first
point of reference for the amount of time that you have to apply the coating
once the components are mixed together. Not knowing a polymer material’s pot
life can lead to aesthetic, adhesive and other coating defects which, in turn
can cascade into loss of time, revenue, confidence and other related problems.
Always consult the coating manufacturer’s guidelines and make allowances for
the variables indicated above.
