You need a light source that has a high UV content, like the Sun (see "Can I Expose my screens in the Sun?". If you are exposing indoors there are lights that are specifically designed to expose screens - Metal Halide lamps (3000W to 5000W); but they can be quite expensive. The older Carbon Arc lamps, not used as much due to their carcinogenic properties. Alternatives are - 400W Mercury Vapor lamps; you will need a high bay to hold the bulb, these lights are also know as factory lights or in some cases street lights. Black lights; these are like fluorescent tubes, night clubs use them, they illuminate your white clothing. You will need a few of them (depending on the size of your screen), they are set up closer to the screen than other light sources, and the distance from the bulb to the screen is the same distance in between each bulb. Be careful of - Flood lights; I have seen many websites that recommend these for exposing but fail to mention that they should be colour corrected. Standard flood lights have a yellow tinge in the light and the safe light colour for emulsion is yellow. If you are currently exposing with flood lights and getting good results chances are that it is the ambient light that is exposing your screen and not necessarily the lamp itself. If you are on a tight budget just use the Sun, even on a overcast day (if you can get sun burnt you can expose your screen). It just takes practice and patients.

Category: Exposing your Screen aka Burning

YES. The sun is the highest source of UV and more than that it is a single point of light. The two main criteria for a great exposure. The only problem with the Sun is that it is unreliable, this is easily overcome with a little persistence and note taking. If you have an old SLR camera, take a reading of the light, then expose your screen for a set time and record the results. If you get good results the next time you want to exposing your screen, take a light reading and then look up how long you need to leave your screen in the sun from your notes. How long would you leave your screen in the Sun? Well there is no short answer, the exposure times will vary depending on: Where you live and the strength of the sun. The time of day. If there is a lot of pollution in the air (generally morning sun is the best) The emulsion you are using and how many coats you have put on. The colour of your mesh. The thickness of your positive (the printout of the image), and what you positive is on (i.e. film or acetate). How dark your positive is in the image area (it should be completely opaque). But if you want to give something ago try this: In the Australian sun; A screen with WHITE mesh that has been coated with 2 passes on the print side of the screen and 2 passes on the squeegee side of the screen, on a really bright sunny day, using a film positive for one and a half minutes. For a screen with yellow mesh four minutes. If you are residing in a place that is further away from the equator first try doubling the time, if that does work double your doubled time (just like an exposure test in photography).

Category: Exposing your Screen aka Burning

Unfortunately it is impossible for us to give you an accurate exposure time as there are many variable to consider, you will need to do a step wedge test to gauge the correct exposure time for the light source you are using. Some of the things that will change your exposure times include: Mesh count - Mesh colour – Emulsion - Coats of emulsion - Light source - Age of light bulb - Distance of light from screen – Positive type and quality. If you are using a light source at a College, or other teaching institution, you should ask their technician or your contact at the college as they will have a better idea of what their exposure times are set for.

Category: Exposing your Screen aka Burning

If the emulsion does not come out of the image are after you have exposed it, it could be a variety of things, some of the most common ones are: - Poor quality positive: the light is passing through the image area. - Poor contact between the positive and the emulsion during the exposure. - Light has hit your screen that was coated with emulsion before you placed the positive on it.

Category: Exposing your Screen aka Burning

Yes you can over expose your screen. As long as the positive is good quality (meaning the image area is BLACK and light can’t pass through) the over exposure will “bend” the light around the areas slightly. This generally does not create a problem unless; 1) You have a poor quality positive 2) You are undertaking high end industry production and halfton work. I would expose my screen for a longer time rather than not enough time, as under exposure is more of a problem.

Category: Exposing your Screen aka Burning

Most emulsions will last for about two weeks as long as; It is kept in a safe ling area (no light is touching it). It is kept away from falls and sharp objects. Your emulsion is not off.

Category: Exposing your Screen aka Burning

Simple answer (not technical answer) is; as a general rule, you need about half the time for white mesh as you do for yellow mesh. Remember the exposure times will change with the intensity of the sun (or light source). You should do an exposure step wedge test see http://www.youtube.com/watch?v=Y_ter_P0CIY as a guide and write down your results. Things that effect exposure times: Light source, Intensity of light, Distance of light, Mesh colour, Mesh Count, Emulsion used, How many coats of emulsion, quality and type of positive.

Category: Exposing your Screen aka Burning

The mesh counts are a measurement of how many threads per measurement unit. So in this situation we have found it is common to not know where the information is originating from. 110 is the thread count using imperial measurements or inches. While in Australia we use metric and the mesh count would be 43 threads per centimeter. Same mesh different measurements. Hope this helps!

Category: Exposing your Screen aka Burning