Experiences in ceramics

Engineer - Raw material supplies for ceramics Technical Consulting

San Mango Piemonte SA Italy

WOLFGANG SIMONIS

Nowadays, in the field of ceramics as in many other creative manual activities, the market, re-proposed in terms of hobbies born from production needs on a larger scale, whether craft or industrial, has made it possible to create small but efficient laboratories that can be installed inside one's own home. Today, anyone interested in taking up ceramics can find all kinds of materials and equipment at their fingertips, from a vast range of ceramic mixtures and ready-to-use glazes and colors, to small, low-consumption electric kilns, lathes, machines for preparing mixtures, as well as mills for grinding the glaze. Numerous training courses help the neophyte to learn the basic rudiments of the technique and to subsequently improve his/her knowledge. Then, there are also a large number of publications in the field which allow you to keep up to date on new techniques, exhibition activities, the work of various artists in the field, etc. Thus, as the techniques are acquired, the material begins to reveal its potential. Finally, the personal way of doing things - - the particular idea of what you want to achieve - - comes more and more into play. Joy is the first conquest: the desired form is created from amorphous matter, the work continues and increasingly complex structures come to life from your own hands. However, once the piece has been shaped, what will its surface character be? The use of commercial enamels, mostly produced to meet industrial needs, does not always meet one’s creative needs. It is therefore necessary to know how to transform them in order to bend them to one's own desire to express. The endless recipes found in many books and magazines often give disappointing results. In fact, the correctness of the chemical formula alone is not sufficient to guarantee the success of a glaze. Many other factors - - from the grinding of mixture components, to the application method on the cookie, to the firing time and temperature, to the oven atmosphere - - influence the behavior, texture and even the color of a glaze. (from "Glazes, Experiences in Ceramics", Vol.2 Horst Simonis). The experience gained over time in the industrial field, along with the technological innovations in the field of tiles and tableware, has allowed me to carry out, over time, research aimed at creating a line of ceramic products with intense colors and material effects. We started with the design of specific Molybdenum, Vanadium and Titanium crystallized frits capable of developing highly aesthetic iridescent and mother-of-pearl separations and shades, with different formulas composed for various temperatures and rapid cycles. The enamels applied bring out the best in the surface of special pieces (structures, engravings, etc.), creating shades and crystallizations which, by "reading" the structure of the support, enhance its aesthetic aspect and make it possible to reduce applications to a minimum and eliminate those which cannot be made on complex surfaces. These products include a range of rustic matt glazes and grits - - glossy with a lustrous effect, satin-finished mother-of-pearl, metallic, etc. - - which have made it possible to satisfy many of the industrial market needs in double-firing, porcelain stoneware and third-firing with increasingly rapid cycles.

SMALTI WG:  HOBBY ARTIGIANO
In ceramics, experimentation on and knowledge of the basic characteristics of the raw materials is fundamental for obtaining high quality products, but even good intuition, sometimes originating from random mistakes, can lead to unexpected results. In fact, at the basis of research in industry, as in the artistic field, the synergic contribution of technical skills, experience and intuition is fundamental. Hence, with reference to the artisan or hobbyist sphere, it can often be seen that meeting specific technical, market or taste requirements is more difficult than it might seem, such as, for example, succeeding in reproducing effects in vertical enameling that are originally created on flat surfaces. The basis of effect glazes is, almost always, the use of special frits whose behavior determines the final result, usually already with a single application of enamel. Frequently, similar results can be obtained at high temperatures, using non-soluble raw materials that would normally have composed the frit. In this research, the use of organic or inorganic additives has often made it possible to carry out problematic applications, such as the use of powder or grit enamels on vertical surfaces, or the application of thick liquid enamels on walls intended for street furniture, without the risk of dangerous post-drying cracks, which can cause partial detachment of the coating from the surfaces.

BREVI CENNI SULLA SMALTATURA
La smaltatura dei manufatti artigianali solitamente si effettua per immersione, a spruzzo o con pennello. A ognuno di questi sistemi deve corrispondere una differente densità dello smalto da applicare; ciò si rende necessario in considerazione di molteplici fattori: lo spessore sul biscotto, il suo colore, il grado di opacizzazione dello smalto, il tipo di smalto da applicare, ecc. In generale comunque, nel caso del metodo a immersione, la densità deve essere compresa nell’intervallo di 45-60°BE (gradi Baume); per l’applicazione a spruzzo, invece, la densità deve essere minore, ma non inferiore ai 45°BE. La misurazione della densità si effettua per mezzo di uno strumento: l’areometro.
Tra questi due metodi di smaltatura il più economico è quello a immersione, perché consente un minore consumo di smalto. Nell’applicazione a pennello, invece, la densità può variare e ciò spesso anche in relazione al raggiungimento di particolari effetti estetici. Una volta eseguita la smaltatura, a pennello o a spruzzo, è consigliabile applicare, sopra il pezzo smaltato, un sottile velo dello stesso smalto, per attenuare gli effetti causati da una eventuale irregolarità della superficie smaltata. Si ricorda infine che, se è stato aggiunto un sospensivante, lo smalto apparirà più denso.

APPLICAZIONE DI ENGOBBI O SMALTI A MONOCOTTURA
For single-fired glazing, it is advisable to calibrate the water content to the minimum possible amount. For this reason, it is essential to use fluidifying agents and cmc glue (approx. 0.2 - 0.4%), to promote adhesion of the slip on the raw mixture, and the use of a suspending agent to prevent precipitation of the suspension. The workpiece to be glazed must be dry and heated to a temperature of at least 50°C to ensure good application of the glaze. For subsequent applications, it is indispensable to subject the workpiece to further drying beforehand.

BOX

insights

IMAGES

Iris glazes
Textural grits
Photos Simonis srl Tecnargilla 2004 and 2006
03A Stoneware Raku Effect
03C Stoneware Raku Effect
TEC.0652AG Bico Glass
30AG-FGX bands SOLARTE stoneware
25CG-FGX semi-glossy stoneware

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