Photoetching at home - Part 2: Laser printer photoetching

A long time ago I wrote an article about how to make simple photoetched parts without using all the photographic mess. That technique was seriously limited in the complexity which could be achieved by hand drawing your final art. Even if you use masks or dry-transfers, there is not much to help you to produce more intricate PE parts.

In this follow on article we are going to increase the complexity of what can be photoetched, but still without using photo-sensitive films to develop the image. The idea is to transfer a drawing made by an ordinary laser printer to the brass sheet, so that the printer toner will act as a barrier to the etching fluid. As you will see, this technique also has its limitations as well, but will add more possibilities to your modeling arsenal and - best of all - it's easy and fun. 

The idea of transferring a laser printed image to the metal sheet is not mine. There are several articles and movies on the subject. However, all of them rely on the use of some kind of photographic paper where the final art is printed. Using heat, that image is transferred to the brass sheet. The problem is how to remove the paper (usually soaked in water) from the brass sheet so that the toner is completely adhered to the brass sheet. I have tried several recipes with dim success rates. And that's where the problem resides: if I'm going to print and transfer 10 sheets of artwork to obtain one usable PE sheet, it will be cheaper to order a professional service.

In order to make it clearer, let's review quickly the method:

1. Laser print your design on a suitable paper (no ink-jet printers here).
2. Press the printed matter against a brass sheet, image (toner) down, using a laminator or a clothing iron (heat is very important).
3. Remove all the paper so that a (negative) image of the design is transferred to the brass sheet.
4. Proceed to the etching phase.

In short, the printer toner will act as the etching-resistive image on the brass sheet, the role played by the photo-resist film in a genuine PE process. By suitable paper I mean a paper which can be safely removed later without taking visible chunks of the image with it. I've tried several types of photographic paper and, even in the cases where I succeeded, it was a tedious process to remove any remains of the paper. I needed something easier and faster, still based on the same principle.

So this is what I got: we need a paper on which we can do a quality print, but at the same time, a paper that won't hold the printed toner very well. This will assure a higher rate of success when transferring the design to the brass sheet. I tried several types of adhesive backing papers. They all failed because they are too much waxed, and no printer delivered a decent result. Then, almost by accident, I found the so called transfer paper. This material is a well known media used to decorate shirts with customized artwork. Google it and you'll find a lot about it. This material has a side A, which is the backing paper, and a side B, on which the art is printed and transferred to the shirt. Another important thing: although I'm going to use a laser printer, the transfer paper used is for ink jet printers.



Side A looks like a glossy paper, but it is not waxed as much as other backing papers that I tested, and this is its most interesting feature: the printer toner will stick nicely to it but still allow its transfer to the brass sheet without much effort. Sibe B is kinda rubber thin skin and we are not using it. Remove the side B and never put it in your laser printer! On the other hand, it seems to be an intriguing material than can be rolled to form bedrolls and tarps, canvas covers, etc... but that's another story:




Our case study will be the leaves of a palm tree for a display base of my Hasegawa 1/72 Ki-61. This is the kind of project suitable for this method, since the result doesn't need to be utterly precise. Palm fronds are not exact, and many times are worn out by wind, sand, and elements. There are many commercial PE accessories for that, but they are expensive, and one fret allows you to finish a single palm tree, only. Here are two  examples:



I reviewed another option a while ago from Voyager, but no way that is a 1/72 scale palm leave. It's more like ground vegetation. So, I started by making my own artwork (if you are interested, here is the pdf file in 2400 dpi resolution). By playing with the aspect ratio of the figure, it is possible to vary the type and size of the fronds. I used three masters:

 


The artwork was printed on the waxed face of side A paper and cut to a manageable size:



Next, a brass sheet was cut slightly oversized
. I used a 0.25 mm thick sheet for the project:



An important step is to remove all bends and dents from the brass sheet. This will be decisive later. You can use a rubber roll or a metal cylinder:


 
Another important thing is to sand the etching surface of the sheet with a fine sandpaper in order to remove small scratches and oxidation marks. These spots will preclude the toner from sticking to the sheet later. Then clean it thoroughly afterwards with lacquer thinner to remove any oily and sanding residue:





Now we are ready to transfer the artwork. That's the easy step. Laser printers use basically the same toner of photocopying machines, i.e., a pigment which can be melted at relatively low temperatures, and that is precisely what we are going to use next. Just lay the artwork down on the brass sheet and press one against the other using a pre-heated flatiron. I like to use a thick cardboard under the sandwich to help to distribute the pressure more uniformly. I also set the iron to its max temperature. Putting my weight over the iron a few times and moving it in circular motions helps to make sure all the artwork is receiving heat and pressure enough. The heat will melt the toner, hopefully making it to stick to the brass surface, since the paper is waxed.




I usually work with the flatiron for about three or four minutes. Then I flip the side and apply heat directly to the brass side for one minute more. After waiting it to cool down completely (watch your hands, it is hot!), comes the time of the truth - peeling off the paper. Using a fine pointed tweezer, lift one of the corners of the paper gently and you will see the black pigment stuck to the brass sheet. Remove completely the paper by slowly rolling it down over the sheet:


 
Here you see that the method is not perfect, and why it probably cannot be used for finely detailed parts: small chunks of pigment will possibly remain on the paper. I suspect that by using a laminator instead of a flatiron would solve this issue, but I don't have one. Using very clean brass sheets devoid of any dimples or bents also helps. Well, here is our developed image on the brass sheet:



The sample shown here presented some faulty spots, exactly where I had small depressions... Fortunately, being a palm frond, it doesn't have to be perfect, and most of these discontinuities can be rectified with a sharp pointed marker.


 
The toner will now play the role of the mask during the etching phase. I painted the backside of the sheet with acrylic paint, so that the corrosion will happen from one side only. The etching followed the usual practice (see part 1). After washing the fret in lacquer thinner and removing the fronds, they were shaped using an embosser and a non-cutting round edge. They started to look quite realistic:


 
The fronds were glued to a small sponge ball impregnated with super glue, working from the bottom (larger fronds) to the top (smaller). Small corretions are always possible by gently bending the fronds afterwards, until they look natural. I painted mine with darker shades of green under the fronds and more vivid ones on the top. The end of the fronds received a touch of yellow-green, while the dead/broken fronds were painted with light brown:




 
After installing it on the top of the trunk, I had a very convincing palm tree:
 




Eventually, I will write an article on how to make PE parts like the pros... I hope this one will do for now.


Rato Marczak 2013