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Apparently invisible. Chemistry in ceramics.
Apparently invisible. Chemistry in ceramics.

Apparently invisible. Chemistry in ceramics.

Aware of how complex the problems related to the world of chemistry applied to ceramic production processes can be, we want to share our knowledge with those who want to orient themselves or train for passion or profession.<br />Through a simple and direct language, the podcast aims to be an educational space with a focus on products, applications and processes.<br />The journey unfolds along the ceramic production lines.<br />At each stage a topic.<br />At each topic a critical issue.<br />At each critical issue, when possible, a solution.

Available Episodes 10

The episode focuses on a subject that may seem unimportant but that, instead, is quite relevant if we consider the recent and new intended use of ceramic surfaces (tables, countertops, etc).

Since tiles now are used not only for floors and walls (but also for furniture: tables, top, countertops, ect) the contact with the food we eat is frequent and it must be considered.

Given that ceramics are, by their very nature, one of the most hygienic and antiseptic material in the world, it is also true that surface protective treatments that are applied after the firing cycle may represent in this perspective a serious issue: the products involved in the process, unlike ceramics, do not undergo to any modification after treatment, being not transformed by the very high temperatures of the kilns.

Even if toxic emissions provided by ceramic glass and protective products are extremely rare, it's nevertheless important to take stock and dissect the issue, looking more closely at all mechanisms (not only related to chemistry) that take place behind the scenes.

This episode is the second part of a general overview about the most important categories of chemicals for ceramic prodution and their positive role in terms of environmental impact.

The perspective wants to scratch - with a deliberately provocatory approach - the idea that chemistry cannot provide, by nature, any environmental benefit.

Actually, if we addressed the subject by using a "magnifiying glass", we would notice that the use of chemicals often allows you to avoid making choices that could be much more impactful.

The challenge is to change perspective, trying to look at the scenario with a different approach, without taking anything for granted.

The episode aims to refocus, from a special and provocative perspective, the role of chemicals used in ceramics: from the beginning to the end of the process, that is from the grinding of the clays that form the basis of the ceramic mixture up to the firing cycle.

The reading filter is "chemicals and environmental impact" and the goal is to break the preconception about the word "chemistry", often related to the pollution, contamination, infections.

We do not want to belittle or deny the wrong use of potentially dangerous products by some industrial producers but, for sure, we also want to fight against the word "chemofobia" that is the irrational fear or idea that all chemicals are dangerous and harmful.

In each steps of the production process, the wise use of chemicals can promote some environmental improvements that should not be underestimated or even disclaimed.

Ceramic glazes can be applied by means of several technologies but the most common and popular is the airless spray system.

However, sometimes glazes can still be discharged on the raw tile by means of bell or vela systems.

Each application system required different evaluations about the glaze's rheology.

The glaze must be marked by specific properties according to the system with which is applied along the production line. The episode focuses on these differences and on the chemicals that can - or must - be used to get the proper features.

At the end, a brief focus on synthetic chemicals, very useful to prevent the proliferation of bacterial attacks before and during application.

In ceramics, the water-based digital system represents a topic of great interest.
The R&D departments of all the players have been doing research for some time, trying to improve the sector with a technology that is already widely used in many other fields of industrial production.

The #technical #problems of both the application machines and the products (such as inks and glues) seem to have been overcome, and the time is ripe for a definitive diffusion of this technology which certainly offers many #advantages at a technical, aesthetic and environmental level.

After a brief introduction to the chemical nature and main characteristics of water-based glues, the episode focuses on the most significant advantages promoted by this important type of product, also highlighting its underlying mechanisms.

In ceramic production, the use of digital glues for glaze and grit applications has almost completely replaced the spray/airless application system.

Even if each glue differently acts on glass powders and grits, there are two main categories that must be considered: solvent-based digital glues (based on non polar solvents) and water-based digital glues (based polar solvents and water).

This episode opens with a general introduction on the chemical nature of these products, then offering two important focuses on the operation and mechanisms of action that they develop on the raw tile support. Both with similarities and differences.

The black core is a localized area marked by a brown/black (or even white) color, clearly visible in the thickness of the ceramic tile.

Its presence is usually sign of inadequate oxidation and it has not to be considered as a defect that compromises the product functionality.

However it's a very serious aesthetic problem, especially if we consider the increasingly different intended use of ceramics.

The origins of this particular defect are many and, according to the specific production conditions, even the actions and solutions to reduce or prevent it can be different.

The episode focuses exactly on this topic, offering a journey that starts at the origins of the problem,and then ending with a range of possible interventions.

After introducing the topic in the previous episode and getting into the details of the problems that may arise before the inkjet application, this new episode focuses on the repellency phenomena that occur after the digital printing process at the interface between the solvent-based inks and the subsequent watery applications of glaze or grit suspensions.

The different chemical nature of the inks (non polar polymers) and all the water-based suspensions (polar), is the basis of the critical issue and it basically results in a incompatibility between the two applications due to a lack of interaction. Just like between water and oil.

The episode looks closer at the mechanisms behind the phenomenon, offering some effective actions to avoid or reduce it.

The ink-jet decoration - that has replaced traditional decoration systems - has removed several problems bringing out, however, new and more complex critical issues.

The new scenario has forced a different attention to all those applications that occur along the glazing line both before and after the digital printing process.

In particular, the different nature of the solvent-based inks, with respect to all the water-based applications of the glazing line (engobes, glazes, grits, etc.), often leads to repellency phenomena that can compromise the proper printing process. In addition, the glaze applied as a final protection (on the ink), when not accurately mixed with proper chemicals, may lead to excessive or low drainage, or even to phenomena of inhomogeneous ink's absorption.

What kind of action must be taken in all these cases? What are the PRIMERS usually involved and how do they work?

The ceramic mixture usually used in ceramic production, largely consists of inorganic raw materials (clay, feldspar, sand, etc.), grinding water and chemical.

These mixtures, since they must be properly managed in the various stages of the production process - from grinding to pressing (or forming) - must be marked by specific and particular features.

In addition to this, the raw ceramic material, once it has been pressed, must have the right properties to prevent and avoid the problems that may occur along the lines (before entering the kilns) and to develop ceramic surfaces without aesthetic or technical defects.

To do this, the use of specific chemicals is a must.

What are the main chemical categories involved and added to ceramic mixtures?

What role do they play and what kind of actions do they promote?