Stack breakage

Stack breakage of porcelain occurs when edges, shelves, mirrors or surfaces of an article break, chip, flake or crack and the cause is to be found in an improper physical load on the respective piece of crockery. The breakage of the item occurs during, in, during or after the stacking process. In principle, stack breakage does not belong to the group of manufacturing defects but is the result of an incorrect or excessive weight load. The degree of damage, time and effect of a stack breakage can be reduced or increased by various factors.

Stack breakage - an example from our collection

Porcelain plates with a high rim, e.g. those in the RT (Reactive Trend) series from Holst Porzellan/Germany, are not stackable due to their shape. As a professional user, you could criticise this lack of usability, but such fashionable dinner plates cannot be produced in a stackable version - or only at very high cost. With such fashionable trend items, design, taste and trend take centre stage and are decisive for the respective group of buyers. Unfortunately, such an urban design language with a handcrafted character is often also due to reduced stackability.

Items such as the plates with a high rim from the Reaktive Trend series are even more expensive and more complex to produce and therefore also more expensive to sell than conventional plates, whether they are labelled as stackable or non-stackable. We include such plates and platters in our collection against our professional claim of necessary stackability and only under pressure from the market, because retailers and consumers have virtually forced us to produce such trendy shapes. The fashionable aspect was allowed to go hand in hand with limited usability. A trendy sneaker is also not suitable for a marathon run.

The stacking of such porcelain slabs is at the discretion of the user and should be adapted to the items themselves and the local conditions. The 20 cm slabs in the Coral and Granito series have an average weight of 550 grams, while the 25 cm size weighs just under 900 grams. The 24 cm slabs in the Carbon, Tierra, Musgo and Arena ranges even weigh just under a kilo. This weight considerably limits the number of porcelain plates that can be stacked directly on top of each other. While ordinary porcelain plates can be stacked 6, 12, 20 high and higher - not pulled (!) - without hesitation, the weight distribution is completely different for porcelain plates with a high rim.

The mirror of a porcelain plate is usually a flat and even surface. There is usually a base ring on the underside of such a coup or rim plate, which guarantees the plate a balanced stability. Due to the material density and strength of hard porcelain, the pressure load weight of porcelain plates can be increased at least tenfold without breakage or damage if the pressure is evenly distributed. Porcelain plates made of hard porcelain (hotel porcelain) of the "semi-rigid body" production type should be able to withstand at least thirty times the pressure load without damage. Professional plate stackers in the catering and communal catering sector (WMF, Blanco, Rieber, etc.) or mobile plate trolleys (Hupfer, Köhler, Chromonorm, etc.), which use lateral guide rails to ensure straight stacking - and therefore even pressure point distribution - even allow 60 plates and more to be stacked or piled up.

The plates with a high rim in the Granito, Coral, Musgo, Tierra, Carbon and Arena ranges have a stylish rim that rises to almost 90°. This shape prevents the porcelain plates from stacking evenly. The pressure point cannot be evenly distributed to the plates below and the risk of damage to the porcelain increases. If such porcelain plates with a high rim are stacked on top of each other anyway - at your own risk - a considerable part of the pressure load of the entire porcelain stack is shifted to the side edges.

The higher the dead weight and the number of stacked panels, the greater the pressure point weight. 12 Coral porcelain plates stacked on top of each other (see picture below) with a tare weight of around 900 g result in an uneven pressure point distribution of 10 kilograms! If the plates are not stacked individually but in small piles - as is usually the case in sculleries - the pressure point load increases considerably, even for a fraction of a second. In most cases, the plates underneath are also not yet fixed and rest loosely, and change their position again when another, smaller stack is placed on top. This is how the dreaded "porcelain crunch" occurs.

 

 

The stacking of such porcelain plates with high edges is usually referred to in the industry as "improper use" according to the rule that the more plates are stacked, the more likely this is to lead to breakage and damage.

Incidentally, the degree of stress and therefore the risk of porcelain breakage is increased exponentially in the scullery, at the Mis en Place or in self-heating stackers. If such porcelain plates with high edges are stacked on top of each other directly after the dishwasher drying process, the physical load (weight) is multiplied by the thermal load (stress cooling) of the porcelain. Between the drying or removal temperature of the dishwasher (max. approx. 85 °C) and the storage temperature or room temperature (approx. 20-24 °C), there is a thermal cooling of approx. 60 °C.

This combination of considerable pressure and thermal load is very difficult for any hotel porcelain to withstand. This explains why some porcelain plates in such improper stacks do not crack or break as soon as they are stacked, but only after hours or even days.  Porcelain that breaks in this way is by no means a manufacturing defect or a faulty product, but solely the result of improper use.

Recommendations for non-stackable porcelain

1. The best solution: Small stacks

2. The most effective solution: Vertical storage

4. The interim solution: stacking aids