The choice of wax printing
By printing wax onto the paper’s surface and applying heat to it the wax is absorbed into the paper’s structure. All areas coated with wax become hydrophobic. The hereby created hydrophilic areas in the paper can be described as potential traces for the later added conductive liquid. While most printed circuit boards create fixed traces by creating permanently conductive trace-structures on a surface, my method creates traces by limiting and controlling the liquids spreading through the whole paper structure. This traces are only potentially and need to be activated by applying a conductive liquid. The created traces will only be temporary, as some conductive liquids – f.e. salt water – will vaporize slowly while being exposed to room temperature.
While testing the advantages of printable Cirquids in my bachelor thesis, I tried three different printing methods for applying the hydrophobic wax into the fiber structure of the paper:
· manual application via candle wax pen drawing
· wax screen printing
· Xerox Solid Ink printer
Which method to use mainly depends on the budget for creating Cirquids, the desired resolution of the cirquit board and the tools that you have available for this purpose.
I focused on using the Solid Ink printer most of the time, because this method makes it easy to produce a cirquit board with a higher resolution while the amount of extruded wax onto the paper can be regulated easily by the digitally created motive that will be printed in a certain CMYK value. Printing different lines with various stroke thicknesses and varied amount of CMYK values f.eg. allowed me to test the minimal needed amount of wax to separate the paper into hydrophilic and hydrophobic areas.
Candle wax pen
Applying wax with a Pic Tixxs Kerzen Pen makes drawing Cirquids quite intuitive and allows a rapid manufacturing without the need of using a computer. The wax has a semi liquid consistency and can be directly applied in a drawing gesture onto the paper; it’s viscosity and the low resolution of the extruder requires a certain amount of practice to apply an even amount of wax onto the paper though. Using a stamp to draw much cleaner outline is one way to produce a straighter wax print.
When heading the printed paper the applied wax lines show a rather high expansion of the wax-print. Depending on the amount of wax, this expansion become even larger. On the picture you can see a wax-print before (left) and after (right) applying heat to it.
I used this method rarely, because I liked to focus on precise and reproducible wax-prints. But for applying wax onto a previously folded paper structure for example, the wax pen method was the best choice. I even used a white-colored Pen to make the wax-print as hidden as possible. You can see the created paper device in another post.
Another approach was using the wax of the wax Pen for screen printing. By using a exposure unit. This method made it possible to create a more complex wax-printing via software and copy it to the screen printing foil. Still, applying the wax manually via squeegee made this method a bit tricky, especially if you have never done screen printing before (like me). All in all for printing out different Cirquid-wax-prints this method could not convince me completely.
Xerox Solid Ink printer
The most suitable method for my bachelor thesis was using a solid ink printer for around 350€. It allowed me to print out various wax-printings pretty handy and quickly. And by using the printing-software I could adjust the amount of applied wax easily. A solid ink printer basically uses a similar principle of an inkjet printer but uses the wax of a solid ink stick. (shown in the picture below)
If it is not possible to receive A4 sheets, using sensitive paper-tape or transparent tape to temporarily fixing the paper on a regular A4 sheet is also possible. However this can cause minor problems, like tape or the round filter paper getting loose while the printing process.
Also printing a wax motive more then two times onto the same area caused the supreme layer of way to flake off.
One main advantage of using a wax printer is the ability to reproduce precise wax printings while the amount of printed wax can be regulated by the printed color depending on their CMYK values, thickness of the printed strokes or transparency. Fine patterns or round shapes can be printed and defined via digital software easily.
Heating up the wax
As the wax print will only cover the surface of the sheet of paper it is necessary to let the wax spread through the depth of the paper. Therefor the paper needs to be exposed with heat. This can be done in different ways, for example by leaving it on a heating plate or using the heat produced by a lamination machine.