Silage wrapping is a blown fibre, most often employed in wet, high moisture baler twine drying. The blow woven fibres are tied tightly to make a strong cover. They rolled tightly onto a beam or other supporting surface; the fibres seal and insulated. Baling with high humidity has grown increasingly popular as it permits an earlier crop time while still avoiding common moisture damage from wet baling.
Although the basic principle remains the same, the method of application has changed. In the past, silage wraps were applied over a wooden frame with a wad of material between the frame and the fabric for extra sealing and UV protection. It was a good way to seal a couple of trees but proved inefficient for larger or heavier bales due to the additional tensile strength required. Today the application method is more streamlined, resulting in a tighter weave that is more appropriate for large scale bales.
Wet silage wrapping was the preferred method, using either a plastic baler twine tied to the beam or a plastic bale tied to the beam, with the plastic bale eventually falling off due to weight loss and moisture exposure. The plastic baler twine was eventually replaced by a metal wire bale known as a baler twine tied to the beam directly. Although superior to the plastic bale for application, both the plastic baler twine and the metal wire bale are susceptible to punctures. Many manufacturers have developed strategies to combat this problem, such as using a second plastic bale tied to the first for added UV protection. Manufacturers also sometimes interchange the metal wire bale with the plastic bale by placing a metal ring on the bottom of each bale to seal against moisture exposure.
There are three main types of silage wrapping methods. The first method involves using a pressurised candle to blow air through the plastic wrapping, creating a high-pressure environment where the product is bonded. However, this method can often result in poor bonding, as the product can become unstable under pressure. Another method uses a blow tube, which creates an even higher pressure environment, making good bonding more likely. A third method utilises a thermal roll formation process similar to spray canning but involves spraying heated rollers over the plastic wrap. The rollers heat up, forming glue and allowing the plastic wrap to adhere to the surface to be wrapped.
With modern technology and the advances in packaging materials, it is possible to create high-quality bales of all shapes and sizes. Bags are available in all sorts of shapes and sizes, including triangular tubes, square bags, round bags, and bags made of polystyrene (a Styrofoam-like material). In addition, silage wraps can be produced using different materials, including corrugated cardboard, webbing, or rope. In addition, some manufacturers use other materials like aluminium to create the wraps. The last two forms have become quite popular over the last few years; the former is generally preferred due to its durability and ability to be re-used, whereas the latter is preferred for sustainability.
Silage wrapping is beneficial not only because of its aesthetic qualities but also because of the chemical and oxygen-free environment it releases during the fermentation process. Hydrogen sulphide and oxygen are the only substances that make contact with the wrap, meaning that the environment is very low in both chemicals. Also, due to the absence of moisture, no bacteria can grow. Furthermore, it means that the wrapping will not harbour mould or other mould-attendant microbes. All in all, silage wrapping provides a safe and effective way to store food and be an excellent packaging source for products meant to be consumed.