Jul 10, 2017 | By David

3D printing technology is becoming progressively more accessible, and with it the demand for easy post-processing methods is also growing. Adafruit has recently published a useful how-to guide on Hydro Dipping, a simple but impressive technique that allows you to add various graphics, patterns and colours to 3D printed objects. Sanding, priming and detailed hand painting of an object could be completely unnecessary if you can get Hydro Dipping right.

Hydro Dipping, also known as Hydrographics or Inket Water Slide Decal Transfer, involves submerging your 3D printed object in water to get an outer coating of whatever pattern or graphics you want. This coating is made from a special ink, which will transfer on to the object from a sheet of paper on the surface of the water. The paper has a film that will wrap around your object to give it a full coating. It’s important to use a relatively large container, with hot water.

The most important piece of equipment that is needed for the Hydro Dipping method, in fact the only thing you need that you might not already have, is a special kind of paper called Water Transfer Paper. One side of this paper is an adhesive matted backing, which can be peeled off, and the other side is a PVA film. Due to its solubility, PVA is also used for constructing support structures for 3D printed objects, which are dissolved afterwards to leave the finished object behind. In this case the film gradually dissolves in water, leaving the printed ink floating in place on the surface, transferring to your 3D printed object as it is submerged.

As for your coating itself, this needs to be prepared beforehand, making use of design software like Photoshop or something similar. Any image can be used, from a color gradient to a particular graphical design or pattern. Some patterns, like woodgrain or stucco, are particularly good for 3D printed objects as they can give the impression of texture when they are applied to a surface. Repeated, homogenous patterns are the best, as the immersion process makes it difficult to get more elaborate images perfectly aligned with the particular parts of the object you want, particularly with objects that have non-uniform shapes. However, researchers at Formlabs have recently carried out some successful tests on hydrographics that could allow for the accurate printing of more complex patterns. Their Computational Hydrographics technique uses a virtual simulation of the immersion process before it happens, so the user can predict where a particular part of the 2D film will align with the 3D object, and adjust the printing of the film accordingly.

An image or pattern with a transparent background can also be tricky, as the gaps in the ink will mean that it won’t cohere as well on the surface of the water as the PVA film dissolves. In this case it’s best to use a very pale shade of grey to approximate a transparent background, or even to try and copy the color of your 3D printed object. Once the image or pattern is made, it needs to be printed on the Water Transfer Paper with a good old-fashioned inkjet 2D printer. Adafruit recommends using the finest quality print setting and making the canvas resolution at least 300 dpi. The PVA side of the paper is the shiny side, so make sure you’re getting the paper the right way round in your machine before you print.

The dip is probably the most straightforward part of the process but also the most important. Make sure you’re dipping slowly, at a 45 degree angle. Once the 3D printed object is fully submerged, shake the water gently to separate the rest of the ink from the object. After the part is removed and the process is complete, it just needs to be dried, preferably with hot air. The ink will dry hard, a bit like nail polish, so it is durable but can still be scratched off. An extra layer of protective spray could be used to make it more permanent.

The Hydro Dip isn’t the most complex procedure and the level of detail and precision is relatively low, so specifically aesthetic or ornamental prints might require something more involved. But for most hobbyists or 3D printer users who just want a basic decorative finish for their functional or novelty object, it’s a very straightforward and effective solution that’s definitely worth a try.



Posted in 3D Printing Application



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Harirambudhi wrote at 7/18/2017 4:32:27 PM:

I need more details about the materials availabe

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