Spanish Colonial Period brick samples dating to the 19th century from the Municipalities of Liliw and Pagsanjan in Laguna, Philippines was investigated. These samples were obtained from two church structures, a church bell tower from Liliw and a church convent from Pagsanjan. Combined X-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF) and Fourier transform infrared (FTIR) spectroscopy allowed the determination of chemical elements and minerals attributed to clay and sand, such as montmorillonite, quartz, corundum, hematite and calcite. On the basis of these compositions, the possible kilning conditions employed to fire the bricks during manufacture was also proposed. MATLAB™ programme was utilised in this study to interpret the data from XRD and FTIR to rationalise the overlapping peaks in the spectrum. Results show that both brick samples were made of clay material that is non-calcareous with low refractory. The firing was performed in an oxidising atmosphere or an open-air environment at an estimated temperature of between 650°C and 850°C. This preliminary study provides a baseline chemical characterisation data of colonial period bricks in the Philippines which will be useful for future conservation and restoration work not only locally but also within the Southeast Asian region.

Historical building techniques have been pointed out as a sample of local resistance to colonial technical influence during the early modern period, although this could not be proven by chemical analysis. A clay brick with an attached lime mortar sample was acquired from the former San Francisco Church’s foundation in Intramuros, Manila, Philippines and representative portions (BRK-1, BRK-2, BRK-3, MTR-1, MTR-2, and MTR-3) of the sample were utilized for chemical analysis using various analytical techniques. These are the energy dispersive x-ray fluorescence (EDXRF), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and ultraviolet-visible spectroscopy (UV-Vis) for quantifying organic compounds. The clay brick sample is made of typical sand and clay specifically composed of non-calcareous clay and low refractory fluxes. The brick’s firing temperature was determined to be between 600°C to 800°C in an oxidizing environment. The attached lime mortar sample is probably manufactured using crushed seashells and classified as a hydraulic lime where clayey and sand particles serving as pozzolans. The lime mortar’s microstructure shows that it is well carbonated. Possible organic compounds specifically egg whites (albumen) which may have been added to the lime mortar yielded negative results. Both qualitative tests (Xanthoproteic Test, Ninhydrin Test and Biuret Test) and quantitative assays (Biuret Assay and Bradford Assay) were not able to detect the presence of any proteinaceous compounds in the sample. It has been established based on this material sample that eighteenth century Asian builders working in Manila kept local traditions and rejected European preferences.