Surface tension gases. The pressure inside an ideal (one surface) soap bubble can be derived from thermodynamic free energy considerations. At constant temperature and particle number, , the differential Helmholtz energy is given by where is the difference in pressure inside and outside of the bubble, and is the surface tension. In equilibrium, , and so, For a spherical bubble, the volume and surface area are given simply by and Substituting these relations into the previous expression, we find which is equivalent to the Young–Laplace equation when . For real soap bubbles, the pressure is doubled due to the presence of two
Solid surface wall cladding, because its seamless properties eliminate gaps and crevices that harbor harmful bacteria. Solid surface is manufactured by mixing acrylic, epoxide or polyester resin with powdered bauxite filler and pigments. The material chemically cures and is heated to 60°C or more. Cured material is then cut in sheets or shapes and sanded on one or both sides depending the brand used. Sometimes the material is brought to 160°C and cooled, to improve its heat resistance. Acrylic-modified polyester solid surface can be mixed one sheet at a time using different formulations, effects and appearances. Acrylic-modified polyester solid surface can be