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A Technical Guide for Wine Producers
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CURRENT VINEYARD AND CELLAR EVENTS
Alternative barrel stacking methods
Barrel maturation of premium white and red wines has assumed an integral role in the production process of these wines. Accompanying practices such as topping up, lees contact, racking and sulphur adjustments demand the most practical and economic barrel stacking method.
The first prototype of a barrel cradle that can be handled with a forklift was designed 30 years ago. Up to then barrels were stacked either on fixed shelves or in a pyramid structure. Since then several developments have taken place and currently the different systems can be divided between those that may be handled with forklifts and those that are modular.
Initially mobile cradles were designed for 225 litre barrels only, but nowadays they are available for various barrel sizes. The vertical space between barrels has also been increased considerably to facilitate practices such as topping up, filling and the cleaning of the barrels. The 2-barrel cradles in particular are popular and the differences between the various designs are minimal. These entail mainly differences in the forklift opening, the surface supporting the barrels and reinforcements of the cradles. In order to facilitate higher stacking, certain cradle designs have been adapted so that the cradles are stacked instead of the barrels. This design also facilitates the stacking of the cradles when not in use.
As far as modular cradles are concerned, there are two approaches. Firstly, where all wine treatments occur with the barrels remaining in position, and secondly, where the barrels are removed from the cradles for any treatment. In the first instance some cradles allow for wheel mounting of individual barrels so as to facilitate barrel rotation.
Websites of various cradle designs:
Apart from the two different types of cradle, the management of barrel lots, mass, accessibility of the barrels, safety, lifespan, corrosion and cost must also be considered when weighing up specific types of cradle.
Although the capacity of barrels may be the same, the physical dimensions of barrels from various coopers will differ. The only solution is to use cradles that are stacked on top of each other, or modular cradles. Different colours for different cradles may also be considered to identify barrel lots.
Barrels with thin staves of 21 to 22 millimetres can only be stacked two or three high. If transport barrels with 27 to 28 millimetre staves are being used, barrels may be stacked as much as six high. In any cradle or barrel system, barrels with thin staves should never be stacked on the bottom tier. In case of stacking, such barrels should also not be turned to the 45 degree position.
Accessibility to the barrels is obviously necessary if wine treatments are to take place with the barrels in situ. In such instances sufficient provision should be made for space between stacks and the direction of the stacks should follow the slope of the floor.
In wine regions that are prone to earthquakes, ensure that slight movement of barrels during a quake is possible. Employee safety is important in all wine cellars. Whatever the reason, it is extremely dangerous to climb onto barrels stacks. Rather use ladders or remove the barrels in question from the stack with a forklift.
When replacing cradles, consider whether new cradles should be bought or whether existing ones might be refurbished. If you decide on the latter course of action, use techniques such as ultrasound to ensure that internal rust weakening, if present, will be discovered.
The high humidity in wine cellars favours corrosive conditions and cellars should have an inspection programme to monitor the condition of shelves on an ongoing basis. External and internal rust and forklift damage demand particular attention. The effectiveness of the standard surface treatment of a convensional steel cradle is only 5 to 7 years. Galvanising or the use of stainless steel cradles could possibly offer a solution in this regard.
The cost of cradles is a conclusive factor and the influence thereof on the final price of wine should not be underestimated. The question to be asked is whether a more expensive cradle will make better wine.
Reference
Work, H, 2005. Practical Winemaking. March/April 2005: 35 - 47.
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