Screen Printing – Exposure Time For Photo Emulsion Coated Screens

Exposing a monitor printing monitor is like exposing a photograph. For the greatest outcomes, you have to have to expose it for the ideal quantity of time. If you hope it a tiny significantly less, or a tiny additional, you will even now most likely be all right. But the farther you get absent from the ideal time, the additional outcomes will experience. The variables for figuring out the proper time are brightness of the light-weight resource, and length from the monitor.

You have to have to make your mind up on a light-weight resource. I at this time use a 250 watt halogen get the job done light-weight with the UV filter glass, and security cage eradicated (you suppose all threats if you take out your glass and / or cage from your halogen light-weight). In the earlier, I have applied a 75 watt incandescent bulb in a reflector with a clamp. Whatsoever you use, make absolutely sure you have some way of clamping it, or mounting it previously mentioned the body for an prolonged period of time of time.

You have to have to put the light-weight considerably adequate absent from the monitor, so that the entire monitor is becoming evenly lighted. If the middle of the monitor is appreciably brighter then the corners, than the light-weight is also shut. The even larger the monitor, the farther you are probable to have to put the light-weight resource. The farther absent the light-weight resource is, the for a longer time the publicity time will be. Evaluate the distances, and document it, so you will be capable to reproduce the outcomes in the long term.

Now you are completely ready to operate a check to locate the greatest publicity time. Listed here are some foundation occasions to begin with (based mostly on a 150 apparent incandescent bulb):

12 inches previously mentioned the monitor, 45 minutes

15 inches previously mentioned the monitor, 74 minutes

17 inches previously mentioned the monitor, 92 minutes

The better the bulb is previously mentioned the monitor, the for a longer time the publicity wants to be. If the wattage of the bulb is decreased, you have to have to lengthen the publicity time. If the wattage is better, then you have to have to shorten the publicity time. If you use a various type of bulb, the time may well fluctuate.

Listed here is how to check for the greatest publicity time:
Coat a monitor with picture emulsion the standard way. Print a transparency with figures from 10 to 90 in increments of five. If you are utilizing a minimal wattage bulb, you really should use better figures in increments of 10. With the light-weight established up, put the protected monitor below the light-weight to be uncovered. Use a clock or prevent look at to hold observe of the time. Just after five minutes, protect the five with an opaque piece of paper or cardboard. Just after 10 minutes, protect the 10. Do this right until all of the figures are protected. Then clean out the monitor. The cheapest figures that are distinctive on the monitor will give you the ideal publicity time.

Source by Robert Jacob

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