Inspired by spittle bugs, which in their larval stage cover themselves with foam to protect themselves from UV rays and predators, just as certain species of frogs protect their tadpoles in foam nests, British physicist and wine vine grower George Klat created a solution to protect crops from frost and other threats.
The idea, which he named Frosco, is a foam made from plant-derived ingredients commonly used in animal feed and human consumption (and which are not dangerous for plants), which provide physical and biological protection to fruit trees, and which can also be easily washed off after climatic events.
This innovation, which began with the support of the Molecular Engineering Hub at Imperial College London, resembles the appearance of a shaving cream. In the case of Frosco, it is a similar formula with organic components that allows it to achieve the volume that will later provide protection to the tree.
Consulted by Redagrícola, Klat indicated that the foam he designed is sufficiently resistant to withstand different freezing cycles.
“What I have observed with woody perennials, such as vineyards or fruit trees, is that the area to be protected is elevated off the ground, so it is different from when you are trying to protect the plant on the ground, where you have the thermal mass of the earth. The idea is to be able to generate this latent heat in the plant, and also to control and contain this energy,” says the Brighton-based Briton, who has already tested this system in several European countries with positive trials in early spring.
Frosco covering a fruit tree.
A PROTECTIVE BARRIER
“The foam, as the temperature approaches zero, becomes denser, crystallizes, and begins to slowly release this latent heat. Because the foam structure contains billions of tiny air bubbles, heat dissipation is very slow, so the heat is contained within the foam. The crucial point is that it is not like a normal aqueous foam, such as shaving cream or anything like a dishwashing soap,” Klat explains about the protection that the foam provides to the plant.
The advantage of this invention would be that it uses the same principles as sprinkler irrigation systems, but with a fraction of the water, which is equivalent to approximately the same amount of water used in ten minutes of sprinkler irrigation, while traditional systems require constant watering throughout the night, in addition to the fact that they need sufficient water reserves to operate.
This solution, which coats trees prior to these weather events, can be applied with a knapsack sprayer as a foliar application, with a tractor-mounted system developed by Frosco, or with new robot-assisted application methods, and is expected to be tested soon in Chile.
Frosco applied in a row with a special tractor-mounted sprayer.
THE KEY LIES IN THERMODYNAMICS
Klat studied physics and natural sciences at Durham University, but in the end it was always about farming and innovation in the field.
His experience in the sciences led him to rethink the idea of aqueous foam as an insulator, something that has been experimented with since the 1950s.
He points out that it was always thought of as an insulating blanket, something that can work in soil crops, but it was always designed with as much air as possible in the foam, up to 99%, as if it were an air blanket, since water, being a conductor of heat, was thought of as something detrimental to keep the heat in during frosts.
Finally, he points out that “what we have done is to change that concept, so that water becomes the active mechanism. We use the phase change of water (from liquid to solid) as the active mechanism. Therefore, it is essential that the foam contains the right amount of water,” he describes.
This is why the design of this foam is intended to contain between 10% and 15% water.
“Water is the phase change material in the product. It possesses higher molecular potential energy than any other known substance in the universe. When it freezes, it releases a large amount of heat, whereas in the foam structure, water is bound to the self-assembling molecular structures we create. This is how we usually think of molecules, individually, but if we think of something like DNA, we see that they are also molecules, but assembled in different geometries, forming helices,” Klat explains.
He points out that foam is based on the same principles, as the molecules, when combined, can be controlled to form different structures, be they sheets, coils or even helices.
“These structures are what hold the water together in the foam in such a way that, as it starts to freeze, all the water freezes at the same rate. It is therefore a coherent freezing front, rather than the surface of the foam freezing and then gradually warming, or the center warming and then gradually cooling,” comments Brtánico.
The key, as the laws of thermodynamics, is that between freezing and liquid foam, temperature is stored, which is latent heat. Therefore, there is no change in the actual thermal temperature. Thus, the foam inside always remains at zero degrees Celsius until the freezing front slowly descends, according to Frosco’s creator.
“This interface, where latent heat energy is released due to the phase change, is contained, and its release is very slow,” he adds.
Structure of the foam through a microscope.
EXTREME FROSTS IN CHILE
How would this foam work in Chile? In 2025, on August 18, severe frosts lasting more than 10 hours with temperatures below 0°C were recorded in the central-southern zone.
Consulted by Redagrícola, Klat pointed out that he has tested the foam in scenarios down to -20°C and it has worked without problems. The difference is in the intensity and duration of the temperature, where the foam can be adjusted.
The only limiting factor to its performance is that more water would be needed to make it last 12 hours. He points out that recently a farmer in Hungary tested the foam at -5.5 °C for nine hours, and for this he needed about 10 centimeters of foam diameter, so it could be thought of as a wall needing two coats of paint.
“This is possible because the air inside the foam is very sticky when it has the right consistency. It has a slight positive charge, is slightly alkaline and sticks to the negative charge of the water. It is a slight electrostatic interaction that is also very sticky. The limiting factor is applying enough foam to the plant, but once it’s applied and frozen, you can apply more,” he says.
In the case of requiring a second coat, once the first coat is frozen, this new application adheres and seals, becoming crystal clear ice, so more foam can be applied. “If it’s going to last more than six or seven hours, then it might need to be applied at five o’clock in the morning or some other time,” Klat explains, to reinforce the application in extreme cases.
