Exposing screens can be both rewarding and frustrating when screen-printing. Excellent films make great screens, and good screens make good prints. Poorly exposed screens can be a nightmare.
The exposure unit uses UV light from 8 black light bulbs to expose screens. It has an integrated vacuum and timer. This light table is super reliable and easy to use, but it can be a little difficult to remember all the steps in the beginning. Use it a number of times and you'll be a pro.
Now let's begin, have your film and a coated, dry screen ready. Touch the screen all over to be sure that all of the emulsion has dried-- examine around the edges of the screen where the emulsion might be thicker or might have dripped. If anything feels damp, give it more time in the dry box.
The time will depend on the emulsion that you are using, as well as the art work. It's a little bit of experimentation to discover the appropriate timing for each exposure table and emulsion combination. I normally use Ulano 925wr, and on this table, I have actually found it to be a pretty reputable 4-minute direct exposure for many of my artwork.
The green numbers are what you will utilize to set the time. Use the black up and down arrows on the timer to change the green numbers up and down to the correct time.
The yellow arrow will let you move through the digits. Move through the digits changing the numbers untilyou have the correct time (in minutes) set in the green numbers. Then hit the blue "mode" button to sync the red numbers with your new green numbers. The time that is shown in the red (top) numbers is the time that the screen will expose for.
Lift the top of the table, this is a hinged frame around a black neoprene blanket. The blanket obstructs outside light while the screen is being exposed, and the blanket will pull snug around the screen when the vacuum is activated.
All of the images and type must be in the proper orientation (absolutely nothing backward or reversed).
Put your screen, mesh side down, over the film. Center the film inside the screen, images too near the edge of the screen will not expose.
Laying a rope over the screen will give the blanket more surface area to snug up to while the vacuum is running. To get a great stencil on your screen, contact between the glass/film/mesh should be very tight. Any gaps will allow light to bend around the edge of the film and overexpose thin lines and the edges of the artwork.
The vacuum offers decent contact, however I do anything I can to improve the snugness between the film and the screen.
Place the rope over the screen and glass. Does not matter if it goes over the image area. Shut the hinged lid of the light table and latch in the front.
The order (from top to bottom) will be:
This will cause the vacuum to flip on and be extremely loud. Let the vacuum run for approximately a minute. This will give the vacuum a chance to get the screen tamped on tight before the light switches on.
While the vacuum is running, I like to take some books and fill the inside of the screen (over the blanket) with heavy books. Put the books over the place where your art is located. This will help with the contact in between the screen and glass, and help keep light from creeping around the edges of the film.
There is a button above the switches that is called the "Push button to activate timer". Push this button immediately. This will set the light and vacuum to the time that you set above. You can now leave the table and leave it to do its thing.
The light will flip off also. The blanket will keep the screen secured and dark as you stroll back to the exposure table, so no requirement to rush. Get rid of the books and unlatch the table. Leave the film on the direct exposure table and take your screen to wash out.
After rinsing your screen and setting it to dry, examine the table. If your screen had any damp emulsion on it some may have gotten left on the glass. It is your responsibility to clean that emulsion off of the glass.
Use Windex, microfiber, and your fingernails to remove the stuck emulsion. Do not utilize a blade or scratch the glass, and do not leave it for somebody else to clean off.
And lastly, remove your films and put them away. Turn the power off. Close the table. Done.
Now you are ready to expose your screens like a pro. Learn how the process of screen printing works. If you would like for us to do the work for you, do not think twice to give us a call at (832) 464-8008. We are readily available 24/7, send us a quote today so that we can start now.