3-D printing uses water-soluble materials to support or support the mainstream approach 3D Printer: Anyone familiar with 3D printing knows how to accumulate objects by layer printing.However, there are problems in this process, that is, the geometry of some objects is special, and the structural layer may be "hollow".Therefore, printing needs a "support structure". Usually, in a single nozzle printer, the same material is used intelligently when printing the support structure.After printing, the supporting material can be removed.This is the most commonly used method, but there are many problems.Most importantly, if the shape of the printed matter is special, the supporting structures are all inside, and removing them may be cumbersome and sometimes impossible. Soluble support materials came into being.At first, people thought it was the perfect solution: after printing, the printer was thrown into the liquid and everything else was done automatically.However, it turns out that this is not the best choice. At present, two types of soluble carrier materials are commonly used: PVA (polyvinyl alcohol) and HIPS (impact polystyrene). PVA is water-soluble and can be used in dual-nozzle printers, one of which prints consumables, and the other prints PVA as a support structure.This material is not only soluble in water, but also easy to remove. If the water temperature rises slightly, it will dissolve faster. However, there is a serious problem with PVA material, that is, it can absorb moisture in the air.More importantly, once the material absorbs moisture, it becomes very sticky and unsuitable for 3D printing.This means that PVA materials must be properly stored and sealed.Once exposed to air, it will not be used.Moreover, the PVA material is extremely sensitive to temperature, if the temperature is too high, it is easy to plug the nozzle.Moreover, this material can not be firmly adhered to the printed matter. HIPS material, this material is also soluble, but it is insoluble in water, can only dissolve in limonene.Limonene is one of the components of lemon-flavored detergent used in household cleaning products.It tastes good.Once the printing is finished, once the printed piece is put into limonene, it will dissolve automatically.HIPS material has no defect of PVA material. However, the solvent of HIPS material must be limonene, not dishwashing detergent in kitchen.Therefore, limonene must be purchased extra, and its price is not cheap.In addition, in most cases, limonene solvents are not reusable.Therefore, the more you print, the more limonene you buy.