Industrial productivity is a top priority for any manufacturing enterprise, regardless of its field of operation.

The ceramic industry, too, must adhere to rules and parameters that enhance productivity while avoiding any form of waste.

However, process interruptions—representing the most extreme scenarios—can be triggered by numerous factors and can occur at various stages along the production line.

Even the digital printing process, including all the micro-processes that occur immediately before and after the printer, can be prone to issues that, in the most severe cases, lead to machine downtime.

This discussion explores some of the most representative critical scenarios related to the topic, providing an overview of preventive actions that can be implemented to mitigate such risks.

Water is one of the most widely used natural resources in numerous applications and across various sectors of industrial production.

For example, process water forms the basis of different production phases and ensures their proper development.

However, not all waters are the same.

Depending on its source, water can have very different properties, which may make it suitable or unsuitable for a specific process.

In general, water quality is often a necessary precondition.

For this reason, there are various processes capable of purifying water efficiently and, most importantly, safely.

One of the most widespread and commonly used methods is reverse osmosis.

Suspending agents belong to a broad category of additives whose primary purpose is to provide ceramic suspensions (slips, glazes, engobes, or frits) with good internal stability, counteracting potential sedimentation phenomena.

Available in both liquid and solid forms, these products act within the suspension to ensure the right balance.

There are various mechanisms that can be employed to properly maintain the solid phase of the mixture in suspension.

Among these, the most significant are about viscosity, electrostatic repulsion, and concentration (solid/liquid ratio).

This episode, after reviewing the properties of suspending agents, focuses on these three main tools, delving into the reasons and mechanisms behind each, also considering the application systems through which suspensions are deposited onto the ceramic substrate—a detail that can significantly influence the type of suspending agent to be used.

Complexing agents are capable of catching multivalent cations present in suspension to prevent them from negatively affecting the ceramic process. 

They are responsible for one of the main mechanisms underlying the deflocculation process: complexation.

Complexing agents (or chelating agents) are chemicals that bind to specific ions (such as calcium, magnesium, iron, etc.), forming stable complexes.

This property allows them to "sequester" metals, making them less reactive or preventing their precipitation in solutions.

These are simplified and very short descriptions of this particular category of additives. 

The episode takes a closer look at the mechanisms enacted by these substances within the ceramic production process, highlighting their functions, benefits, and sometimes, risks.

The topic of non-planar surfaces, which develop on multiple micro-levels and are sometimes improperly identified as 3D surfaces, plays a crucial role in giving ceramic surfaces not only a more natural appearance but also a broader and more extensive expressive potential.

This is not a new requirement: it took its first steps with the help of traditional technologies, but it has found new momentum with the arrival of the latest digital techniques.

The episode offers an overview of the main methodologies currently used to achieve textured surfaces, delving into the chemical mechanisms that occur on the surface and contribute to producing the desired effects.

In the previous episode (#45) we discussed the technical aspects of digital printing systems in relation to ceramic bricks.

This second part looks at the necessary preparatory work for the printing phase, going through the various steps involved in preparing a print file.

Regardless of the media on which you will work.

Some key words: standardized lighting, colorimeter, spectrophotometer, linearization, chart...

At present, in the heavy clay industry, products are decorated mainly by applying engobe with the aid of scattered granules or by means of reduction effects created by the firing process.

These techniques are suitable to produce traditional products for the existing market. 

What added value does digital printing offer in this field?

The operating temperature is an important parameter that ceramic producers must take into account in order to avoid application problems that can also negatively affect the quality of the finished product.

However, this parameter is not always easy to manage, especially if we consider the fluctuations promoted by seasonability.

The episode addresses the topic with the help of specific examples, highlighting the main scenarios and the different levers on which one can act to better manage the anomalies that may occur along the production lines.

Most ceramic production processes involve the dispersion of ceramic powders in a liquid medium - mostly water - to obtain a suspension or, more generally, a dispersed system.

To provde the suspensions with the desired stability and workability, depending on the different applications, we use the addition of small quantities of suitable chemicals that, interacting with the solid particles, change the rheological behaviour of the whole system.

The episode offers a picture of two categories of chemical - deflocculants and binders - almost always involved in order to achieve the right result and therefore the correct application performance. 

All analysis of ceramic suspensions carried out by those companies that supply chemicals for ceramic production are fundamental to properly develop the processes that take place along the production line.

The episode provides an overview about the role of these important investigations, with a focus on the data and on the operations of the involved tools.

We will talk about jars, pycnometers, laser granulometers, sieves, rheometers, pointing out how all these tools are important in providing ceramic producers with the correct information to proceed without problems or unexpected critical issues.

After addresing the impact that seasonality can have on the the fluidization of ceramic mixtures and on bacterial proliferation within semi-finished products, this second part of the episode 41 tries to show and explain the consequences that temperature changes may produce on the drying time of ceramic suspension, leading to alterations that often force producers to revise the parameters of the glazing line.

After offering the usual suggestions to handle the problem, the episode ends with a focus on the solubility of surfactants that can be also susceptible to seasonal and temperature changes.

In ceramics, the use of chemicals plays a fundamental role in providing the final product with high technical and aesthetic results and in promoting a proper application process.

However, their actions can be sometimes less effective or compromised. 

There are several reasons for this performance change and seasonality is surely one of the most interesting.

Through a series of examples, the episode addresses the actions that should be taken to prevent the temperature to negatively affecting both processes and products.

Glaze and grit suspensions are made up of a liquid part (usually made-up of water and one or more rheological chemicals) and a dispersed solid part.

However, these two different suspensions show a lot of differences that may lead to very contrasting results, also implying a different approach about chemicals, both during the grinding phase and along the glazing line.

From this point of view, all chemicals involved must be marked by specific features according their intened use. What do we need to know about the subject?

Cratering phenomena are defects that appear as microscopic craters on the surface of ceramic bodies on which an aqueous (and still drying) suspension has been discharged.

It is an application problem that leads to a misalignment of the suspension due to the presence of one or more dips.

The problem, that is already visible along the glazing line and not only after the firing process, may arise for several reasons: for example due to the presence of impurity within the ceramic raw materials or because of an improper use of defoamers.

The episode try to offer a list of the most important causes, pointing out the mechanisms behind the problem, also providing some suggestions to prevent and/or eliminate it.

CMC are organic compounds, water-soluble polymers derived from cellulose, widely used in several fields of industrial production. In ceramics, sodium CMCs perform multiple functions within suspensions and solutions and can be marked by very different properties depending on the situation.

What is the main role of this substance in the ceramic production process, and what needs to be done to properly manage it?

The plasticity values of ceramic mixtures is a very important issue, since it affects the values and features of the mix and therefore the proper development of the ceramic production process.

In general, the use of clays marked by high plasticity values is usually synonymous with easier process management.

However, high-performing clays are not always available and it is therefore important to keep in mind other production parameters, finding a balance or even good compromises.

After a short definition of this amazing physical property, the episode offers a general overview on the issue.

Not only in relation to tiles production.

In ceramics, digital technology (use of digital glues and digital inks) has definitely riform the sector, making the production process much more flexible and expanding creative and aesthetic possibilities.
The extraordinary precision with which the ink is discharged on the ceramic support, in fact, has opend to new extraordinary results.

However, the topic "printing definition" must be addressed with great attention, being subjected to several variables that can affect the final product.

What are these variables? What mechanisms are behind them and what can be done to not compromise a good resolution?

Scanning Electron Microscope is a sophisticated tool used in many fields of scientific research, even in ceramics.

The use of an electron beam instead of light allows to get not only outstanding high resolution images but also detailed information on the composition of the sample.

Insights are so accurate and exhaustive that offer manufacturers clear solutions or, at least, suggestions about the actions that should be taken to properly solve production critical issues.

How does the tool work and what are its most important functions to support ceramic industry?

Sodium silicate is an inorganic substance that at room temperature it is in solid state.

It is a chemical compound used in several areas of industrial production. In ceramics, sodium silicate is very effective within ceramic mixtures.

Among the several effects it produces, it plays a very important role in terms of fluidization.

The episode is about the function that this substance performs, highlighting its several properties and the benefits it promotes.

With a focus on deflocculation of ceramic mixtures.

Polluting and odor emissions are two important critical issues that producers have been looking for some time with considerable attention.

This is a problem that appears in the final stage of the ceramic production cycle, inside the kilns, but whose origin can be found in the previous application processes that mostly take place along the glazing line.

Scenarios can be different but emissions are mostly produces by the use of digital glues and digital inks that, due to their particular chemism, can be considered the core of the problem.

What do we need to know about it?