1. A dark film positive:This is probably the most important. With a good film positive you can expose your screen longer and the light will not affect the image area.
2. Correct positive contact: This accompanies the dark film positive hand in hand; you need to ensure that you have a good positive contact.
3. Dry emulsion: Your emulsion must be dried onto the screen before you expose it. If your emulsion is not dry, it will not properly expose. The emulsion on your screen should feel smooth like plastic, not sticky or wet. Having a well ventilated and dry darkroom will help screens to dry.
4. Fresh exposure bulbs: Keep in mind that all exposure unit bulbs have a shelf life. If your exposure unit bulbs are old, they will not expose a screen in the same amount of time as a new bulb. If you notice that your screens are starting to under expose, increase your exposure time by 10-15 percent. If you find that you continuously need to increase your exposure times, it’s probably time to replace your exposure bulbs.
5. Exposure calculator: An exposure calculator is a simple way to gauge your exposure. This simple step wedge calculator helps you dial in your exposure times and gives you recommendations on increasing or decreasing your exposure for optimal results.