In this article I am going to tell you about the 3D printing technique which is used for full color printing from sandstone of lifelike sculpture and models. BJ or Binder jetting, is a 3D printing technology in which the object is built by the printer from thin layers of powdered material - similar to the way SLS works - with the help of binding agent which is delivered by a nozzle to connect the powder. There is a difference between the two, however, because the SLS uses a laser that sinters the layers together instead of using a binding agent.
As the process starts, the first action, in this 3D printing method, is the binding agent being spread over the first layer. That way the powder is being bound together. When the biding agent is spread well and bonding process for the fist layer is complete, the powder bed slightly moves down. After the platform drops, the powder gets spread over the next layer by a roller or a blade and is ready to be bound again. As any other technique, the object is being built from the bottom up. Building an object with the BJ technology, does not require additional support as the the powder that is not melted acts like a support for it. Not having to worry about the object falling apart is a great advantage and so is the fact that it saves some time, by not having to remove supporting materials from the finished object. This is another similarity with the SLS, however in this case the object needs to be cleaned from the powder left on it after it's finished, while with the SLS this is not needed. The most common material which is used for printing with BJ is the full-color sandstone. It comes with the strength of not being too pricey, but there is also the downside of the printed objects not being very durable. For now the BJ is mainly used in industry. Apart from sandstone, there are other materials, that can be used as well. Two of the alternatives are ceramics and food. The ability to easily add full color palette is another advantage of the BJ 3D printing. It can be added to the binder. However the objects created with this method are not very strong and require further treatment. For example the ceramic and metal materials need thermal post-processing to become more durable, while the polymers need to be enhanced with infiltrant to improve color and strength.
BJ 3D printers are mainly used in industry and it is not available yet to the normal consumer.