Almost everyone is familiar with the Barcode, also known as the Universal Product Code (UPC). It was introduced in supermarkets for inventory control 1n 1974. Today, every product has at least the barcode attached for scanning. The image on the right is a QR, or Quick Response code. Both of these codes use OCR, or optical character recognition software to be scanned and read. But that is where the similarity ends. The barcode has space for 20 digits and is read by interpreting the width and space between the bars. But it can only read in a horizontal plane.The QR has a capacity of 7,089 characters and can read both in the horizontal and vertical plane! The three squares in the QR allow the code to be read in any position so that scanning is very fast, in milliseconds!
The QR code was developed in Japan by a subsidiary of Toyota, Denso Wave, for the inventory of automobile parts. Introduced in 2000, the QR caught on and soon smart phones had the ability to take a photo of the code, read it, and allow the consumer to go to a website, a magazine, download an mp3, or find a sale in a nearby store. The concept has been slow to catch on here but with the explosion of iphones, it will not take much longer to be a dominant code. There are code generators available on the web so try it out.
I was doing some exercises in imagination and it may be possible to get even more information in the code by using 3D technology or by using color. Interesting thought. Just another project! Click click...

As promised in the last post on photograms, here are my results with real blueprint or cyanotype chemistry. Photo 1 was made using a high contrast negative on inkjet transparency. Photo 2 is a negative printed circuit image that I had made some time ago. Photo 3 is the dye made from the reaction of the two chemicals used after the mix was exposed to light and the water evaporated. The dye formed is Prussian Blue, sometimes called Turnbulls's Blue. The chemicals needed and the formula are below, and at the end of the post, I will provide a source of the ingredients, and a great reference site:

• Potassium Ferricyanide (10 grams dissolved in 100 ml distilled water) Sensitizer called part A.
• Ammonium Ferric Citrate Green Variety (25 grams dissolved in 100 ml distilled water) Sensitizer called part B.
• Mix part A with part B in equal amounts in subdued light. (About 15ml for an 8X10" sheet of paper).
  
• Coat paper with a foam brush in subdued light. Watercolor or coated inkjet paper works best but any paper will provide an image.
• Let paper dry in a dark place. Image in the sun or source of UV for 10 to 20 minutes. Color of the image should be almost gray or appear over-exposed.
• Rinse image in a couple of changes of water and let dry. Image will intensify as it dries.
  

This should provide a good start as to what can be an addictive hobby. It can be a real challenge to get images that are exceptional, but also great fun. As with all chemicals, be careful and locate the MSDS, (material safety data sheets) on both chemicals. A very good site for cyanotype and other photographic processes can be found here.  A site that I have used successfully for these chemicals and other photographic chemicals also sells a cyanotype kit. From the description, it appears that you only have to add distilled water and mix. It is less expensive to use the kit if you only want to try out the process. But the other chemicals are available in several different quantities if you want to go further. I have had good service from here. Good luck and send questions in the comments section and I will update the post.

Photograms are images made on photosensitive paper called Sunprint. The paper is essentially blueprint paper or some form of cyanotype.  The chemistry is potassium ferricyanide and iron ammonium citrate in solution.  More about this at the end of the post. The image is made by placing an opaque object on the paper and exposing it to the sun. The image is then washed to remove the unreacted chemicals for semi-permanence. But what can you do if you don't have the chemicals or the Sunprint paper? Make your own using construction paper!  Most dollar stores have variety packs of construction paper in many colors. This paper is cheap because of the low quality of pulp used, and the dyes that are called fugitive. They fade easily in the sun. So, I took samples of all of the colors in the pack and placed opaque quarters on the samples and put them is the sun for six hours. I wanted to use reflective metal to minimize the effect of heat on the dye. See before and after photos below:

The sample with the most contrast seemed to be the red, so I used a fern under a piece of glass to make the image in photo one at the top of the post. But this has other potential as well. How about testing several types of clear plastic the see if they have UV absorbers? Or different colored plastic? Theoretically, yellow or amber should block blue and UV while blue will pass all blue and UV. What about putting a thin film of sunscreen with different SPF values. Well, you get the idea. For the next post I will show how to make blueprint paper with the above mentioned chemicals. Pretty cool and the image only requires about 20 minutes of sunlight. Stay really still and smile!