1. Co Developer of Prime Cast, an epoxy modified primer with nano technology.
With the demise of the old solvent methly methacrylate Canyon Tone stain due to the lowering
of VOC’s, the only real option has been water based products to stain/paint exterior precast
concrete wall panels. A few exceptions are the high build VOC solvents, some of which carry a
five year material and labor warranty that is pro-rated. Most of us remember the old solvent
Canyon Tone stain as the product to go to that never failed. Most of us still refer to painting
precast as staining because of the Canyon Tone solvent we used for so many years.
Problem with water based products.
Water based paints bond only through chemical key, thus if there is a foreign substrate is on the
surface the water based paints will not bond. All cement will invariably have some laitance or
unhydrated cement on the surface of the panel, both substances are hydrophobic and cannot
be removed by simple power washing and most definitely latex paint will have a weak bond
adhesion if any at all. The only alternative is to lightly sandblast or acid etch the panels giving
the latex a mechanical key to bite to or pre-prime with a solvent. Due to the chemistry of latex
paints, they are very permeable, allowing vapors to pass through in either direction, good in
most instances. However, picture the make-up of latex paints as rubber balls stacked up on the
surface. The area between the rubber balls allows solids to pass through. When moisture
passes through the precast panel it dissolves the soluble stances in the cement and carries
those solids to the exterior surface (in between the rubber balls so to speak) and the soluble
substances get trapped in the latex coating or fully come to the surface. Those soluble

2. substances are efflorescence, that nasty looking leopard spotting we witness in the paint that
we once thought it was just the paint fading.
If we can prevent the efflorescence from coming to the surface, latex will have color longevity far
beyond that of any oil based paint.
Problem with VOC compliant solvents currently on the market.
Solvents will generally bite through or adhere to any laitance or unhydrated cement on the
surface of precast concrete wall panels, but as mentioned above solvents have poor color
retention especially in mid-tone colors and generally they are not even available in deep tones.
When a deep tone is specified, we typically over coat with a latex product. When cracks develop
in the concrete, the solvent will also crack, thus allowing water to enter which in turn creates
efflorescence that will push the solvent coating off at the crack line.
Understanding the problems and utilizing the best of both worlds.
With the help of a paint manufacturer, we co-developed an epoxy modified primer with nano
technology that is VOC compliant. Five years in the formulating and field testing we went into
full production in 2014 applying Prime Cast to over one million square feet of exterior precast
wall panels. There is no other product designed and built from the ground up to deal with the
issues of precast concrete wall panels. Once the Prime Cast is applied, we can over coat with
any quality latex product flat paint, acrylic elastomeric, or silicone elastomeric. So impressed
with Prime Cast is one major coatings manufacturer, that they offer a five year material and
labor warranty over the primer, unheard of in the industry!
Will Prime Cast adhere to the two component polyurethane caulk? Tremco, a manufacturer of
two component polyurethane caulk tested the primer applied to concrete prior to caulking. It was
then tested by pulling until sealant failure occurred. The caulk failed cohesively by tearing within
itself while maintaining adhesion to the precast primed surface. As long as the caulk is properly
mixed at the joist, Prime Cast will adhere to the caulk if over-coated.
Now jobs that are fives years old look as good as the day they were painted and at a cost the
same as the solvent high build.