Steps on Preparing Positive Image and Exposing Emulsion to Sunlight ~ theHANDrawn

8.8.16

Steps on Preparing Positive Image and Exposing Emulsion to Sunlight

4:45 PM Color Separation, digital textile printing, sensitizer and glue, Silk screen printing, T-shirt printing, tutorials 1 comment

Note: This is a continuation of a previous post.

START HERE!

Step 3: Prepare your image

The emulsion on your screen is photosensitive; when it’s exposed to light, the emulsion hardens onto the fabric and becomes water-resistant. So, to put your image on the screen, make a “positive” with an opaque, black image on it (blocks light) and a transparent background that lets light get through to react with the photo emulsion.

An easy way to do this is to make a black and white image using Adobe Photoshop CS6 or CorelDraw X7, print it on a bondpaper.

More ideas:

It’s even possible to make a “grayscale” screen print, where solid black areas on your printed image end up entirely clear on your screen, and gray areas are a pattern of tiny black dots that become tiny clear spaces on your screen. To do this, you’ll still need to start with a fairly high-contrast black and white image, then convert it to bitmap. A resolution test pattern (like this classic RCA test pattern) helps with calibration and makes a neat screen printed image by itself, too.

Here's a tutorial on How to make CMYK pattern for T-shirt printing.

Since both of your screen and image are ready, it's time for the next step.

Step 5: Expose it then rinse

If you already have an exposure box, you can use it in this step. Those who doesn't know what exposure box is ― it is a light box or light table, with several fluorescent bulbs set directly under a glass, allows for simpler set-up and shorter exposure times, but may take some experimentation to figure out what the correct exposure time should be. Depending on what light intensity you have coming out of the light box, your exposure time could be around 6 or 7 minutes.

But in this tutorial, since not everyone has an exposure box, we will do the old way ― the direct to sunlight exposure.

Exposing Emulsion to Direct Sunlight Setup:

Before taking your completely-dry screen out, get the rest of your exposure rig put together.

You'll need:

a sheet of glass to cover the screen, foams and a hard board

of course, your image

(note: to obtain a transparent background,

spread cooking oil using a cotton, if printed on a bond paper)

Put the foams under the screen,

We are going to set the screen with the bottom side facing up.

Lay your image and the glass on top of that, make sure to place your image backward, facing the screen and against the glass, so that it is in correct position when you look at the bottom side of the screen. This is especially important for text and numbers.

and lastly put the hard board at the bottom.

Now, find a good spot outside for your direct-to-sunlight exposure.

The exposure time? Just 1... 2... 3... 4... and that's it!

Now the exposure is done, remove the glass, the pattern, the foams and the hard board, then rinse the screen.

Spray the screen using the Pump up Hand Held Pressure Sprayer. As you spray, you’ll see clear areas developing where your images blocked the exposure light; concentrate your spraying on those areas. Hold the screen up to the light; the mesh of the screen fabric should be entirely clear and open in your image areas. If it’s not, keep on spraying.