How long do you expose speedball emulsion?

Exposure Time 45 mins.

How long do I expose photo emulsion?

Here is how I gauge the exposure: the emulsion is a slime green color and as it exposes it begins to turn to a dark gray/green. Once you see it darken considerably it has been exposed….it should only take 2-3 minutes depending on how strong the sun it.

How long should I expose my screen in the sun?

Tape it down and lay the glass over it. If the sun is out, take the screen outside and expose it for 30 seconds, you might have to experiment with this time. After you do this a few times you will know. If it is cloudy or early or late in the day, you will have to expose it for a longer period.

How do you measure exposure time for screen printing?

Calculating Your Exposure Time

1. *Guess how long it will take for your screen to burn (Ex.
2. Take that amount of time, and multiply by 1.5 (Ex.
3. Take your new time calculated in Step 2, and divide by 10. (
4. Tape the calculator to screen, and cover all but the first row with thick, opaque paper.

Can you over expose photo emulsion?

Over-exposure causes a loss of detail in your image area. When photo emulsion is exposed to UV light, it polymerizes or will crosslink, making it more difficult to wash out. Extreme over-exposure can “burn” through the opaque areas of the film positive rendering the stencil a solid block of hardened emulsion.

Does photo emulsion expire?

Keep them in a cool place. Diazo emulsions have approximately a one year shelf life if kept at room temperature and no direct sunlight. They will last longer if at a colder temperature. Don’t buy more than you need in a few months, and if you do keep it cold, but not freezing.

What happens if you over expose emulsion?

Over exposure. Too much light “cooking” the emulsion. This will make it hard to wash out. This can lead to the temptation of blasting the screen with a higher water pressure.

What happens if you over expose a screen?

An overexposed screen won’t allow for enough ink through your screen while printing— resulting in prints with poor detail. An underexposed screen means you’ve lost too much emulsion and you’ll be throwing too much ink.

How long does an exposed screen last?

A coated and properly exposed screen should last indefinently depending on how you clean the ink out after every print run.

How do you know if photo emulsion is bad?

You can’t really tell by looking (as long as it was sealed). If the emulsion doesn’t perform like it used to and you increase your times and still can’t get a good burn, then most likely it’s bad. You can place the emulsion in a refrigerator to make it last longer.

How to use Speedball photo emulsion for screen printing?

For the Speedball photo emulsion I’m using here: Fill Diazo Sensitizer bottle 3/4 full with cold water. Shake well. (The sensitizer was a black sludge on the bottom of the bottle, so mixing it thoroughly required lots of shaking and stirring with a chopstick.)

How to determine the best emulsion exposure time?

To determine the best exposure look for; edge definition and degree of unexposed emulsion on the squeegee side while washing out. A properly exposed screen will have less slime on the inside as the exposure light has burned 75 to 90% of the emulsion. Be aware on finer detail you may want to cut back time to maintain the details.

What kind of emulsion do you use for screen printing?

I used Speedball diazo photo emulsion and diazo sensitizer; the exposure times I list later in this Instructable are for this formula. If you use another type of photo emulsion, be sure to read the directions and test to make sure you have the correct exposure times. @ lots of newspapers (to keep everything else clean!)

What happens when photo emulsion is exposed to light?

Photosensitive emulsion hardens when exposed to light, becoming insoluble in water. By blocking light where the image will be, that emulsion remains soluble and can be removed allowing ink through the mesh. Thanks! When using a photographic table for light exposure, what factor will I consider in selecting the right lighting?