Introduction

For my final project, I decided to research the process of silk screening an image onto a T-shirt. Dr. Bordley suggested the idea to me and even though I had no previous experience with this procedure, I was willing to give it a shot. This is a fairly complicated process with lots of chemistry and art mixed together. There are many different chemical, light, and color reactions that take place throughout this procedure. Many companies today use machines to make hundreds of t-shirts a day with precise borders and complex images. The old hand held way is for those who are patient, have a steady hand, and an artistic eye. Throughout this page, I will show you each step of the process from start to finish. I will tell you the factors I kept constant and the ones that changed. I will try and make it seem as if you are with me each step of the way. Let's make some shirts!!!

Background

Since I had no previous experience with this process, I had to do a little research first. I searched the web and found a couple of really good sites, listed below, that helped me get a general idea of what I was getting myself into. I also was directed to Ms. Christi Teasley, an art teacher at St. Andrews. Without her, my project would have sunk like a rock. She helped me with any questions I had, and was supportive through every step. For a little historic background, the silk screening process was used as early as 2500 BC. The Ancient Egyptians and Greeks were the first to experiment with this method. Silk screening never really became big until 1907, when Samuel Simon was the first man to put a patient on the process of using a silk screen to transfer an image; he used only one color. Just a few years later, a man that had been experimenting with Samuel, John Pilsworth, was the first to discover and patient a multicolor method.

The color scale I used was the CMYK scale. It represents the subtractive nature of color. When you mix red, green, and blue, you get cyan, magenta, yellow, and white, but when you mix CMY, you get black. This is explains why you use transparencies, which will be explained later on. We use the negative side of the transparency so that it keeps light away from the areas that we don't want it to touch.

Procedure

This procedure looks simple, but its actually fairly complex. There aren't that many steps, but each step is important.

Step 1: Stretching and Coating the Screen

The first step is to create the screen you will be using for the shirt. The screen should be bigger than your design, and is usually made out of wood. You start at one corner of the frame and work your way to the other. This will ensure that you have a taught screen. When you apply the staples, you should put them in at an angle because the screen will be less likely to rip if it's on an angle. Once you have the screen in place, you might want to tape the edges of the frame so that the screen doesn't fray.

Once you have the screen stretched and taped, you are ready to coat your screens. If you are doing a multicolor project, you will need one screen per color. Now, you need to coat the screens with a light sensitive emulsion. This emulsion can be applied with a scoop coater. Apply the emulsion with one smooth even stroke to both sides of the screen. Store the coated screen in a light proof area for 24 hours so it can dry. Once the emulsion has dried, you are ready to expose the transparency.

Step 2: Creating and Printing the Transparencies

Now that you have freashly coated screens, you need to make the transparencies from your image. Adobe Photoshop is a wonderful program that will divide your image into the different layers of CMYK. It also allows you to print them individually, which is a huge help. Print out each layer on a seperate sheet of paper. Next, you need to find some transparencies that you can use in the copy machine. Once you have these in your pocession, you can print them. Set the copier to its darkest setting, and print the transparencies. The darker they are, the better because they will let less light through.

Step 3: Exposing and Cleaning the Screens

Once you have your dry screens and transparencies, you are ready to expose the screens. In a darkroom, take your screen out of the light proof box. Place your transparency on the screen backwards, like you would see in a mirror. This way, when you ink the screen, the image will come out the right way instead of backwards. You can use ordinary Scotch tape to hold the transparency in place. Once it's in place, place it under your light source, preferably a halogen or florescent bulb that hasn't been turned on yet. Next, put something onto the frame and screen that will keep it firmly and evenly spread over the light. In my experiment, I put down a piece of felt, then a cardboard piece, then a couple stacks of magazines. This kept the frame pressed firmly against the glass of the light box. It makes a HUGE difference if you don't hold the screen down. Once you have the screen in place, you can expose the emulsion. It's probably a good idea to make a few extra screens so that you can make a test screen. This is just like in photography where you expose the whole image for awhile and then start covering up sections so that some are exposed more than others. This will allow you to find the proper time to expose the screen. Once you've found the proper time, expose all of your screens, one at a time.

Once your time is up, take the screen to a sink and rinse off the excess emulsion. It takes a little scrubbing, but its starts to come off after about 5 minutes. Once you have been scrubbing for about 2 minutes, it's alright to turn on the light and see your finished screen. Once you have all the screens exposed and cleaned, you are ready to print.

Step 4: Printing on T-Shirts

Now that you have your screens exposed, your ready to print. First, you need to order the special ink used in this process. You mix this ink with a base which acts kind of like an activator. The ink is actually a liquid plastic which is activated at 300degrees F for 1 minute. This allows your image to stay on the t-shirt longer than regular ink would. Next, you need to outline your image with ducktape so that you won't get ink on other parts of the shirt. I used ducktape and then put newsprint down under the screen, just to be safe. Also, make sure the t-shirt stays taught!! If it wrinkles during the inking, it can ruin your image and the shirt. You mix the ink and the base with a 1:1 ratio, and spread it along the top of the screen. You then take a large squeegee, at least bigger than your image, and pull the ink across the screen towards you. I found that 4 strokes works really well. Once you've pulled the ink over the screen a few times, pull the screen off the shirt and see what your image looks like. Immediately after printing, if you are only making one shirt, rinse off the excess ink. This will ensure that your screens will last longer and don't get stained by the ink. You just put one color on top of the other, starting with the lightest, and make sure to line up the text and the image correctly. I have found that you get different effects if you switch the order of colors around.

Observations and Data

Each of these is essential to the project and they are very easy to mess up. A wonderful example of this was when I tried to create the transparencies. I used an inkjet printer with special transparencies and it turned out horribly. The black was very opaque, and it had lines throughout the image. When I first tried it on the screen, my results were terrible because it let too much light pass through. Ms. Teasley came to my rescue. She told me to print the images out on normal paper and then use the transparencies that you use in the copy machine. This way I could control the darkness. This worked wonders!!! I turned the darkness as high as it would go and it worked the next time I exposed the screens.

My first set of observations were taken when I first recieved the ink and base. I had to fin ethe correct ratio of ink to base.

These observations and data weren't conistent because I was eyeballing the amount being mixed. Towards the end, I decieded to have a closer mixture. Also, I was using newsprint to print on. I had to change the ratio and amount just a little for the T-shirt material.

Once I had the ratio of ink to base, I had to fine the right ratio for mixing colors. Not that this step is necessary, it was just an extra step that I took just to see if it would come in handy later on.

I had attempted to mix color on the fly before doing this experiment and I obtained these results from my experiments with the mixing. Some pictures are shown below.

As you can see, I got some of the colors but not all. Thats when I went ahead and mixed up some of the other colors to see what I got. I found that I had to premix a few colors before I could get colors like orange or pink.

After finding the correct ink ratios, I had to coat the screens. I used a light sensitive emulsion, that when exposed without the activator mixed in is a bright blue. When you mix in the activator and you expose it to light, it turns a bright green.

When testing the screens for how long you need to expose them by making test screens, one must remember to expose the entire screen first and then cover up sections. Ms. Teasley and I made the mistake of exposing a section and then exposing the entire screen. This mistake took up about a days worth of work.

Once you have the screens exposed and ready for printing, you must remeber the printing process. In order to make sure you just get ink on your image, use duck tape on the parts of the screen you don't want ink to come through. This will also give you cleaner edges. Make sure you tape both sides because if you only tape one, some excess ink will get trapped underneath and bleed onto the rest of your shirt.

	Before I inked my shirt, I made sure to spread an even amount of ink over the top of the screen. This would ensure that I wouldn't have any areas that were lighter in color or missing ink.
	Remember to always pull the squeegee towards you. If you push it away, you might end up moving the screen with it. It's a lot easier to pull the screen towards you and use a little pressure to keep it in place. Remember to keep constant pressure throughout the printing process.
	This is actually a mistake that worked. I used yellow ink of the cyan screen and cyan ink on the yellow screen. This was taken right after I had removoed the cyan screen. Ths final result turned out very interesting because the type was purple and had a green drop shadow.

Conclusions

In conclusion, my hypothesis was way off from what actually happened. My hypothesis was that I would expose all of the screens and my image would work the first time with roughly 2-3 minutes of expose time on the screens. In actuality, the exposure time turned out to be 4.5 minutes and I had to go through about 3 days of test strips because I was doing them backwards. All of the factors that I kept constant stayed constant, and all of the changing factors changed multiple times. The transparencies and the exposure time were the two things that I had the most trouble with because they are the two most important parts of this process. Once I got those down, it was just a matter of rinsing the screens and printing the shirts. This was a wonderful experience for me and I'm sure it will be for the rest of the class when they make their own shorts later on in the week.

Links

http://science.howstuffworks.com/light.htm

http://inventors.about.com/library/inventors/blprinting.htm#silk

http://home.howstuffworks.com/question322.htm

http://www.homecashbusiness.com/tutorials4.htm

Other References

I did not use anything other than the net or personal sources.

Acknowledgements

I cannot give enough thanks to Christi Teasley. She helped me through every step of this project. I came in and she was just backed up with work and she still worked with me and showed everything I needed to do and how to do it. Without her, my project woud have flopped. She deserves just as much credit for this as I do. Thank you so much!!

I would also like to thank Dr. Bordely. I know this wasn't what I origionally wanted to do, but you gave me the idea and I loved every minute of it. Thanks for a great year of Chem and Art, and I wish you the best of luck in the future.