## 4 Two-Phase Media
Each of the analyzed types of rock, due to its chemical composition and color, is likely to be suitable for microorganisms requiring appropriate elements. Although marl and melabasanite abound in Ca, both may have the same calcium-demanding microorganism. For all the analyzed rocks, their color may also be important. A dark or even black rock, exposed to solar radiation, heats up much more than a light or even white one. For the samples analyzed, low-porous and low-absorbing melabasanite, which is rich in minerals Al, Fe, Mg, Ca and Na, will heat up more than slightly less porous and less absorbing red sandstone containing Si, Al, and Fe minerals. The lower temperature will reach a bright, low-porous, and very absorbing marl, built mostly of CaCo\({}_{3}\), while the relatively lowest one will reach also bright, but much less porous and less absorbing granodiorite, which in addition to SiO\({}_{2}\) contains minerals rich in Al, Na and K.  
**5. Possible Application of Galvanic Systems**  
**Galvanic macrocells. ** Our first experiments were constructed with electrodes in the form of long bars of 2-3 mm-diameter and 5-10 cm length. This GALVI system can be used in wooden buildings against colonization by _Serpula lacrymans_, _Gloophyllun trabeum_, and _Schizophyllun commune_. **Galvanic microcells. ** This next GALVI system was formed with electrodes that were in the form of metal grains of Zn and Cu deposited randomly on the surface. The zinc grains (anode) had diameters under 90 \(\mu\)m and copper grains (cathode) with a diameter under 63 \(\mu\)m [84]. Galvanic microcells were used in the paints production of GALVI technology in many variants:  
1. Paint with Zn and Cu that can be used inside damp lodgings (butchers, winery, bathrooms, collars, storehouses, museums etc.). 2. Paints with Zn and Cu that can be used outside in modern building elevations. This is a watertight system for use on facades that are at risk of fouling, with harmful microorganisms in objects with a higher exposure to biocorrosion. Grains of metals will be dipped in the matrix (Figures 8-10), but their tops will be free and stand up. This is necessary for the function of the electromagnetic field when the paint surface will be in damp conditions. 3. We also suggest using paint with Zn, Bi, and Cu (three-electrode systems) on the lower side of the stretchers. This system is the source of bioactive \"ions cocktail\" [78], and it works only at a very fine level on the lower surface of the stretcher. Metal ions cannot come through the canvas and damage the upper part of the stretcher. Metal grains should be added to the GALVI systems by the users directly before the application. Then, the paint must be mixed with a manual or mechanical stirrer to ensure an even distribution of electrodes in the coating. All GALVI systems do not work in very dry conditions, but in such conditions harmful biodeterioration fortunately does not occur. When a place with GALVI coating is damp, then the action of the electromagnetic field starts. We are planning future experiments, forming a GALVI system with a transparent base composed of ethyl silicates, fluorosilicates, epoxy resins, or acrylic resins. It can be used in decorative stone walls or elevations, as well as in artistic concrete. It is possible that our methods could be used in antimicrobial technology in architecture and art. Microorganisms have never adapted to the high electromagnetic field's strength, which contrasts with traditional biocides. Figure 8: Paint surface with metal grains, 3D front view, Alcor R&D Center unpublished report, project No. POIR.01.01.01.00-636/20. Figure 9: Paint surface, cross section, visible metal grains on undulate surface, scale bar = 200 μm, Alcor R&D Center unpublished report, project No. POIR.01.01.01.00-636/20. **Author Contributions:** A.C.: carry on experiments, collected data from experiments of Galvi and two-faze media, produced photographs and wrote the paper, participation in preparing the patent application, corresponding author. W.S.