We found an interesting research published by Torino University (Italy) in the field of Cultural Heritage studies about the analysis of Sepiolite clay synthetized with Maya Blue Indigo dye. This is a well-known pigment in restoration industry, used mostly in Pre-Columbian America to create a synthetic blue colouring.
Sepiolite is resistant to external agents, even if it is weaker than palygorskite1. Both clays can be used in combination with Maya Blue indigo.
Sepiolite is a material widely used also in the chemical, pharma and other industries as a porous material, highly absorbent.
In this case a TG-IR-GCMS system has been used involving only TGA and GCMS instruments for a sequential analysis of freshly synthetized sepiolite and sepiolite mixed with indigo Blue Maya pigment. Both mixtures have been analyzed, starting from the weight loss in the TGA from room temperature up to 1000°C, then gaseous samples have been conducted to the GCMS.
Samples comes to be different in weight losses, moreover GC-MS analysis highlighted an indirect evidence about the encapsulation of the dye in nanotunnels. The transformation of the chains of elements and the simultaneous loss of indigo, changes the clay channels giving more durability and stability to the sepiolite mixed with Maya Blue.
The potential fixation in both palygorskite and sepiolite matrices of differently colored dyes, may lead to the creation of a new category of pigments.
Moreover, fibrous habit of sepiolite clay is not dangerous for human health, the absence of poisonous materials (heavy metals) and the low production expenses would ensure to be ecologically oriented and cheaper, making the environment healthier with breathable and sanitized walls.
1Sepiolite like Palygorskite, is generally reputed to be essential components of one of the most famous and studied pigments: the Maya Blue. This dye is prepared by grinding and heating the clay powder with the pigment. Palygorskite has been widely studied than the sepiolite. Sepiolite is known to be lower resistant than the other clay.