Unifix is used for preparing shoe impressions in loose soil before casting with plaster of Paris.
Unifix will penetrate the porous structure of soil and sand to fix them, moist or not. The surface of the impression will be sealed and impenetrable for the plaster after preparation with Unifix. The result will be a cast with better details and less adhering soil.
If the soil with the impression is very loose like pure sand (on the beach or in the dunes for example) it is best to first make the impression slightly humid by spraying a fine mist of water over it (spraying horizontally) so that the water droplets drift to the surface by gravity. Then proceed with spraying with Unifix.
To not disturb the impression the aerosol can should be kept at a distance of 25 to 30 cm and moved in a zigzag pattern while going from one end of the impression to the other. To prevent caving in of the impression it is best to start fixing with the outside of the shoe impression.
It is best to spray "wet on wet" when fixing with Unifix - so not let the layers dry in between subsquent sprayings. Drying of the Unifix will be faster when the temperature is higher and airflow (wind) stronger.
As a last step before the pouring of the plaster a treatment with silicone spray (SLM) can be done. This will further prevent soil particles from adhering to the cast.