What is White Ink Printing? A new UV technology explained.

Mitesh Sanghani

August 20, 2020

Create prints that are part transparent & part opaque. A new option for branding glass partitions.

All digital printing inks are transparent. The base on which the inks are printed, lends the print, its opacity. For example, when an image is printed on a white sheet of paper, the opacity of the paper ensures that you cannot see through it.

On the other hand, if you print the same image on a transparent plastic film, you can see through the image, onto the other side.

In both the above cases, the printing inks are transparent. But the media that these inks are printed upon, decides the job’s final opacity.

While all digital printers come equipped with four colors CMYK, there is a newer breed of machine that prints in a 5th color, that is…

White Ink for an inkjet printer.

And white ink printing technology makes some pretty interesting printing applications possible. Let us have a look at the inkjet printer that prints white ink.

White Inks Are Opaque

The CMYK set of colors in a standard printer are transparent. They have to be so because these four colors mix up with each other to produce all the visible colors in the spectrum. White inks, on the other hand, are opaque. They do not allow light to pass through.

So, using white inkjet inks, in combination with a specialised technique called layering, we can create prints which are partially opaque and partially transparent.

Using White Ink Layers

When we print an image on a transparent film with regular CMYK inks, we end up two distinct areas:

The image area (where the inks were applied)
The non-image area (where there were no inks or printed images)

If you remember, from our previous example, the entire print (including the areas where the images were printed) became transparent. This happens because, in addition to the base media being transparent, the inks on top allow light to pass as well.

Now, because you can see through the printed area as well, the image on a transparent film looks slightly dull. Please look at the first column of the second row in the image below and you’ll see what I mean. The light passing through the transparent inks results in a reduction of the vibrancy of the image.

But by using a layer of white inkjet inks, we can solve this problem.

Here is what we do…

We first deposit a layer of white ink on the transparent film/media. This layer is in the same shape as the final image. For example, if I have to print the letter ‘A’ in red color, I first print the ‘A’ in the same size, shape, and position, in white ink.
White inks are opaque. So effectively, I have created a white opaque area on my transparent film in the shape of the letter ‘A’
The next step is for me to overprint (print on top) of the white ‘A’ shaped layer. I now print the letter ‘A’ in red color exactly on top of the white layer.
The white layer is now fully covered by the red colored print. It is hidden and cannot be seen.
But when you hold up the print to the light, you will see that the red letter ‘A’ is now opaque. This is because the lower layer of white ink, (although hidden under the color inks layer) imparts opacity to only that area where the inks are deposited.
This gives us a beautiful dual effect of a partly transparent and partly opaque glass film.
1. The image area (where inks are deposited in two layers (white + color) becomes opaque.
2. The non-image area (where there are no inks) remains transparent.

How White Inks In Inkjet Printers Overcome the Problem of Transparency in Printing Inks?

Look at the examples in the above image.

In the first image, we are printing white on clear vinyl which is pasted on a piece of glass. The vinyl print blocks our vision completely and you cannot see the sheet of glass.
In the second image (row 2, column, 1) the same image of a flower is printed on a transparent film. Now, while you can see through the glass sheet, you also find that the print itself looks a little faded. Here the red inks, being transparent, are allowing the light to pass through.
In the third image (row 1, column 2) a white layer is applied exactly beneath the red flower. Here, the image now becomes bright and vibrant. It is also opaque. The non-image area (or the rest of the film) remains transparent and allows vision to pass through.
The fourth image (row 2, column 2) is just a reverse view of the previous example. We can see the layer of white ink beneath the red flower. This is the layer that lends opacity to the image.

Other Applications of White Inks

In addition to helping create prints with dual effects of transparency, white ink prints also have other applications. Here are the reasons people get white ink printing service:

Decorative Films for Glass: Interior designers look for frosted and transparent film prints to decorate the glass partitions of an office or living space. While inks for glass film prints on these partitions are a dime a dozen, prints with white inks stand out and look especially rich.
Reverse Pasting Films / Reverse Pasting Stickers: White inks are used extensively to create stickers that get reverse pasted. For example, the stickers on your car windscreen get pasted from inside the glass. You have a layer of glue on the color printed image, to begin with. The white layer is placed on top of the printed image to lend it its opacity.
Three-Layered Printing: In this option, we print two layers of different colors with a white layer sandwiched in between. For example, a film showing a red car on one side and blue on the other can only be achieved, using white layers.

Real-Life Example of a White Ink Job

The images of the office partition (below) are of a project executed for Ms. Shubham of Acuiti Consultants, Baner. She needed white ink printing service. She had two office partitions and she wanted to brand the same with white inks for glass film prints.

This client wanted to display a flow chart of her business processes on the partition. There was a workroom on the other side and she wanted to be able to see on the other side as well.

Moreover, the film had to be pasted from behind the sheet of glass, because she wanted to make notations with a whiteboard marker on the partition, from the front. We used white ink UV white inks for the printing to give her a satisfying solution.

White Ink Printing Machines & Technology

White ink printing technology is relatively nascent in the print industry. In its initial avatar, machine sellers used to retrofit 4 color eco-solvent machines to run white inks as an additional fifth color. But there were a lot of technical problems and white ink eco-solvents failed to really take off.

Of late, UV white ink printing machines come preinstalled with a white ink option. These machines are pretty stable and have gained wider acceptance in the print community. For running white inks on your machine you need to be aware of the following:

You need an additional printhead to channel the white ink in your machine
The white ink configuration will cost more than the basic 4 color options
The run cost for white inks is higher
You will need design expertise to create separate layers in files. Layered printing is necessary to produce white ink jobs

If you are a print vendor looking to buy a printing machine, we have two blogs that can help you get started. Do have a look at the same when free…

Other Options for Glass Branding

While white ink prints are a very premium option for branding glass partitions, we do have a whole lot of other options to do the same. So you might want to have a look at:

Opaque and transparent glass films: As the name suggests, these films can totally cut or fully allow light to pass through your glass partition or building facade. They are widely used for branding in corporate offices. Do click here to know more about printable glass film options.
Frosted glass films: Frosted films impart a rich ‘smoked’ or ‘dusted’ look to your glass panels. They ensure privacy for the people inside the office. And at the same time, these films allow natural light to pass through. These premium grade films will add a touch of class to your office interiors. Do click here to know more about frosted films for branding on glass panels.
One way vision glass films: This is a pretty intelligent idea for branding glass in commercial spaces. You print your branding/product images on the film just as you would, on any regular vinyl print. But when you paste it on a glass partition, this film imparts a dual effect to the same. Customers on the outside, get to see the printed imagery. But employees working inside the office can see outside. This film fulfills a dual purpose of privacy and enabling commercial advertising. Click here to learn more about one-way vision films.

Conclusion

White inks when used judiciously have the potential to enhance the offerings of a print service provider. Also, such a unique solution will help in generating extra revenue. All you need is a little bit of specialised knowledge and equipment to make it work.

Finally, Dear Reader, I would love to hear what you think about this write-up on white inks. So be sure to let us know, in the comments section below. Cheers.

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Mitesh Sanghani

Mitesh lives, mostly for Saturdays. But when forced to work, you'll find him heading Orchid Digitals - a printing press in Pune. If its an emergency, try looking for him in the hills behind his house. He'll almost certainly be under a tree, with a book in hand.

What is White Ink Printing? A new UV technology explained.