All I had to do was Google "water slide decal" and the information was right there. The following is from Wikipedia:
Water slide decals (or slip decals) are water-mounted decals generally printed face up and rely on the dextrose corn sugar residue from the decal paper to bond the decal transfer to a surface. A water-based adhesive layer can be added to the decal to create a stronger bond or may be placed between layers of lacquer to create a durable decal transfer. The paper also has a layer of glucose film added prior to the dextrose layer which give it the adhesion properties, the Dextrose layer give the decal (lubricity) the ability to slide off the paper and onto the substrate.
Water slide decals are thinner than many other decorative techniques (such as vinyl stickers) and as they are printed, they can be produced to a very high level of detail. As such, they are popular in craft areas such as scale modeling, as well as for labeling DIY electronics devices, such as guitar pedals.
Until recently, water slide decals were professionally printed and only available in supplied designs, but with the advent of printable decal paper for colour inkjet and laser printers, custom decals can now be produced by the hobbyist or small business.
Source: Wikipedia Water slide Decal.
There are plenty of instructional videos on Youtube for making and applying your own.
I also found out that I can print my own water slide decals on paper readily available for home printers. So all this language "the test was sent to a new partner we have overseas who recreated the shapes for us in vector format and from that, tiny waterslide decals are generated. " just means it's made in China.
Here is the text from the IT email.
Many of our astute fans have commented online that there was something different about the eyes of two of IT's recent dolls; Anika Luxottica and the W Club Upgrade Vanessa Perrin. We can confirm that those observations are correct; we are using a new technique to improve eye consistency.Based on the ongoing feedback that the team has received expressing concerns about sometimes subtle or pronounced balance issues with the screening on various dolls, IT is currently testing a new water slide application method for their doll eyes that will eventually eradicate this issue completely.This relatively new method has been around for a little while now and is being used by more and more companies in the industry. The W Club Liaisons sat down with Alain Tremblay to ask about this new, promising method to address some of the concerns that we read online... read on!W Club Liaisons: Alain, thank you for taking the time to get back to us. The Anika Luxottica doll that was unveiled at IFDC is a huge hit with fans and everyone was impressed with her, especially her edgy facial screening. Can you please elaborate a little more about the technique that was used to create this screening?Alain T.: Thank you, I'm glad everyone loved this girl; I had a blast designing her! The new technique is actually really interesting! We decided to test it out on her first and then, Vanessa since Anika's eyes are so detailed and different than the other dolls that we've done in the last few years. To achieve this new look, Jessy Ayala and I collaborated to create her initial makeup look, then the test was sent to a new partner we have overseas who recreated the shapes for us in vector format and from that, tiny waterslide decals are generated.WCL: Is the entire makeup on Anika and Vanessa applied using this technique?AT: The technique we are developing could basically be called a "hybrid application method" if you'd like. Only the eyes (outline, white, iris, pupils and "catch light" dots") themselves are applied this way, since those are the most complicated/multi layered segments that are on any doll's face. The rest, i.e., the lips, eyebrows and eye-shadow layers are sprayed using the traditional mask and airbrush technique first, before the eyes and eyelashes are applied on top. This way, the eyes will be balanced, since generating these shapes in vector art is more precise than spraying the entire screening in multiple-layers the traditional way.WCL: Is this new method durable? Will the eyes come off easily? Many are concerned about this.AT: Once applied, the water slides are sealed with a topcoat, so yes, it is perfectly secured and should not be any different from the traditional mask layer doll eyes. Of course, it goes without saying that using alcohol, acetone or heavy scrubbing will damage the paint on any doll. Common sense applies....WCL: What other IT dolls sport this new method?AT: At the moment, only Anika Luxottica and the Upgrade Vanessa have it, but a few of the upcoming dolls in the 2016 FR Collection will also be created using this new, cutting-edge method.WCL: Alain, thank you for taking the time to explain this to us and we look forward to what new exciting things the team will be able to create using this method!
Let's be clear, waterslide decals have been around for a very, very long time. It is not a "relatively new method." Decals are used in many other industries and are extremely durable. I'm fairly certain that the tattoos used on a series of Sybarite Dolls are waterslide decals. (Gothica (not shown), Neurotica and Toxica.)
Tonner's Zombie Boy - this had to be mostly applied decals. In this Tonner photo below, left, one can see the edge of the applied decal on the forehead.
Water slide decals are different from ordinary decals and stickers:
Different variations of decals include: water-slide or water-dip; and vinyl peel-and-stick. A water-slide (or water-dip) decal is screen-printed on a layer of water-soluble adhesive on a water-resistant paper, that must first be dipped in water prior to its application.Source: Wikipedia "Decal"
Upon contact with water, the glue is loosened and the decal can be removed from its backing; overlong exposure, however, dissolves the glue completely causing the decal to fail to adhere. A peel-and-stick decal is actually not a decal as described above, but a vinyl sticker with adhesive backing, that can be transferred by peeling off its base. The sign industry calls these peel-and-stick vinyl stickers vinyl-cut-decals.
Source: eBay Auction
IMO (as always) the bottom line is that decals, used appropriately and according to need on dolls, can result in excellent effects. If used just to make it easier for a factory to get things right...well, that's another story.
Those of us who were Fashion Royalty collectors from the beginning know the difference.
Here are a few early Adeles and Veroniques. No decals, no lashes, just nicely painted faces. Everything changes. Most of us hope that things will get better along the way. This is an expensive hobby. It's a luxury and the dolls must match up to the high standards collectors are paying for.
Click to enlarge.