Viesor Labs

Ratatouille

Last December I got so involved with my school work that I nearly forgot about inevitably approaching Christmas and the traditions that it brings – presents!
With approaching holidays most of the time you think that you still have time to buy presents and keep putting off this sometimes frustrating errand as long as you can. I am not going to speak for all the people out there because some do sincerely enjoy this process. In any case, I am not one of them.  Furthermore, I am a person who prefers hand made unique presents to all the “standard” ones bought from a local gift store.

Sparing you of all the details, I had to come up with a present idea. When I was a kid I used to be fond of a craft called pyrography.
Pyrography is a craft of using a very hot object of either one or different shapes: sharp for fine features, dull for bigger ones, and locally burning out a pattern or an image on flat or, sometimes, completely arbitrarily shaped wooden objects. Here is a simple example.

Pyrography, Simple Example

I bet, there are plenty of commercially available tools for this purpose, but, guess what? - there was no time for me to look and buy any of them. I had to find something at hand that I could use for this purpose.
Most of the time, the tip of such a tool represents a sharply bent wire which serves as a passage for a high current and therefore heats up to red or even white. The material that I know for sure can be used in this application is nichrome. The reason why this material is perfect for the purpose is the metal’s high resistivity, and thus, even a short piece of wire will be enough to create a sufficient resistance to plug in a general purpose power supply (typically a transformer) without drawing too big currents. Finally, from high school physics course we know that power is equal to P=I^2*R.
Luckily, I work in a research laboratory and there one can find tons of various things, just laying around, that “no one” needs. The search lead me to high power wire resistors. Even though the housing of the resistor was made of some sort of ceramic, a big hammer could always adjust revolting nature of parts, especially if they are not designed to be used for some application. Several strikes crashed the housing of the resistor and I was able to extract the wire out of it. Hooking up a short piece of the mined out wire to a power supply and tuning it to several volts led to the expected effect – the wire first became hot, then red, then white (matter of fractions of a second). Even though the wire was pretty thin I had plenty of it in the case it broke or burnt.
I chose a terminal block that is usually used on PCBs as a wire terminal/holder (it had bulky metallic sockets that could fix a wire with a lock screw) to hold my burner and soldered thick wires to the other side of the block and then hooked it up to a power supply. My tool was ready and actually came out somewhat convenient to hold.
I used a piece of plywood of an appropriate size as my canvas. Preparation included solely sending down one of its surfaces smooth.
Time to put my artistic skills into use came. However, being a lazy person and not having to much of time I decided to copy an existing picture that I could find somewhere online. Even though I am not a fan of plagiarism this time I gave myself a “go”. Being aware of the fact that coming 2009 was a year of a rat (Chinese calendar) I chose a nice picture of Ratatouille
Now I needed to transfer the picture onto my canvas. One way to do it is to use a hard pencil and draw the exact picture on wood by pressing the pencil only slightly. Obviously this approach needs one to posses good drawing skills and quite some time and therefore was not a solution for me.
First, I used GIMP (Photoshop will do just fine) to prepare an auxiliary image. I used a Sobel edge detecting filter to detect edges. Generally, it depends on quality and colors of an image, so sometimes it might be necessary to play with de-saturation, edge detection, brushes or whatever else is useful to achieve black and white contour version of the original. One final thing that I did was  - I mirrored the image – you will understand the reason for that shortly.
Once I was satisfied with what I had I printed the prepared image on a blank piece of usual office paper. It is important to use a laser printer in this case! as I was going to use heat to transfer the image on wood. To do the trick all that I needed was a typical household iron. After flipping the prepared printed image with the ink toward the wood, placing it on the smooth wood surface, and ironing the sandwich for some time I got a slight imprint of the original image transferred on the wood surface.
All that I had left to do was to trace all the ink imprints with the earlier prepared wood burning tool. See for yourself what came out of this idea.

Ratatouille, "Pyrographied"

Final touch - a coating of polyurethane. and …. Done!

Ratatouille

I am not too proud of what came out of this project as it could be way more professional instead of looking like a craft by a 5-year old. But, taking into account the tools and the time – could be worse

Tags: gift, pyrography, wood working