How CryoPaint Cools Surfaces With Physics

If a coating could drop surface temperature by up to 15°F without any external input, the first reasonable reaction is skepticism. Free cooling sounds like a perpetual motion scam. It is not. It is heat moving from a warm body (your surface) to a colder body (deep space) through a wavelength band where the atmosphere stays out of the way. The Second Law of Thermodynamics is honored at every step. Here is the actual mechanism.

Step 1: Reflect almost all the sunlight

The first job is to not heat up in the first place. CryoPaint reflects 94% of incoming sunlight across the UV, visible, and near-infrared spectrum. That is at the top end of what is achievable with a sprayable paint. A standard white exterior paint reflects in the 75 to 85% range; a premium cool-roof coating reflects in the 85 to 90% range.

Reflecting 94% versus 80% sounds like a small change. It is not. Sunlight on a flat surface in Phoenix in July is roughly 1000 W/m². The difference between absorbing 4% and absorbing 20% of that is 160 W/m² of solar load that never enters the surface. That alone keeps CryoPaint cooler than every standard coating before any other physics kicks in.

Step 2: Radiate heat in a wavelength the atmosphere lets through

Every surface above absolute zero radiates thermal energy. The wavelength of that radiation depends on temperature; for a roof at roughly 75 to 100°F, the peak emission lands in the 9 to 11 µm range.

Earth's atmosphere is mostly opaque to thermal radiation. Inside one specific band, between roughly 8 and 13 µm, the atmosphere is transparent. Heat radiated in that band passes through the air column and reaches outer space, which sits at about 3 K (around -454°F). Any wavelength outside that band gets absorbed by water vapor and other gases in the atmosphere, which then radiate the heat right back down.

CryoPaint is engineered with 90% 8–13 µm emissivity, meaning in the wavelengths that bypass the atmosphere, it radiates its own heat to space at 90% of the maximum rate possible.

Step 3: Net out the energy balance

Add the two effects together:

• Heat absorbed from the sun: minimal (only 4% of incoming).
• Heat radiated out to space through the atmospheric transparency window: significant.

When the radiated heat exceeds the absorbed heat, the surface loses energy on net. It keeps losing energy until it reaches a temperature where the math balances out again. That equilibrium point can sit several degrees below the surrounding air temperature, even with the sun directly overhead.

This is not unique to CryoPaint. The physics has been published in peer-reviewed journals including Nature and Science. The contribution of CryoPaint is putting the optics into a waterborne paint that you can apply with an airless sprayer.

How it operates

There is no compressor, no pump, no fan, no sensor, no controller. Once the paint is dry, it cools whenever it has line of sight to a cold sky. It cools during the day. It cools at night. It cools in winter. It does not turn off.

What it cannot do is move heat against the temperature gradient (it cannot make a surface colder than the sky temperature it sees), and it cannot generate cooling power on a surface that the sky cannot reach.

When the math stops working

The Second Law sets the ceiling. Real-world conditions set the actual delivered performance. CryoPaint delivers close to its maximum cooling when:

• The surface has a clear, mostly unobstructed view of the sky (do the YMCA "Y" test: arms up into a Y, look up. If you see blue sky between your hands, the paint can radiate heat through the window).
• Relative humidity is low (below roughly 60%). Above that, water vapor narrows the atmospheric transparency window and absorbs IR before it can reach space.
• Air is still. Convection drags the surface temperature back toward the air temperature - the same reason blowing on cold coffee warms it up. Gusts and light breezes are fine, but sustained wind above 5 mph measurably shrinks the temperature drop, and it keeps shrinking as speed rises. Corrugation ridges, parapets, and wind shadows mitigate it.
• The surface is relatively flat. Performance drops off above about 30 degrees of tilt from horizontal.
• There is little or no insulation directly behind the painted surface. PDRC is an active heat pathway from interior to space; insulation blocks the heat from reaching the paint in the first place.

If any of these are off, CryoPaint still reflects 94% of sunlight, which keeps the surface at or near air temperature. That is still better than every conventional white coating.

Where this matters most

The best CryoPaint use cases are surfaces where heat has nowhere else to go and the ambient is hot. That includes:

• Metal roofs (low insulation, sky-facing, hot summers).
• Shipping containers and storage units (uninsulated steel, full sun).
• RV and trailer roofs (low insulation, occupants want a cooler cabin).
• Equipment enclosures, control boxes, and outdoor electronics (no fans, no airflow, sun-exposed).
• Vehicle roofs on fleet trucks and school buses (cabin temperature drives HVAC load).

Bottom line

CryoPaint cools by reflecting almost all of the sunlight that hits it and radiating the rest of its heat to outer space through an infrared band the atmosphere happens to let through. It runs on physics that have been published, replicated, and licensed across the industry. The performance ceiling is up to 15°F below air temperature; the conditions that let you hit that ceiling are listed above.