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Screen printing exposure unit
A screen printing exposure device is a machine used to create screens for screen printing. It uses ultraviolet (UV) light to expose a photosensitive emulsion that has been applied to a mesh screen. The emulsion hardens when exposed to UV light, creating a stencil that can be used to print designs on T-shirts, posters and other materials.
This depends on the amount of UV radiation emitted by the exposure unit. The emulsion-coated screen printing mesh reacts only to UV radiation. The black positive film blocks the UV radiation, and where no UV radiation hits the emulsion, it is washed out. This is how we transferred the film to the screen.
Explore the possibilities of our exposure units!
The different types of screen printing exposure equipment are UV curing systems, vacuum exposure machines, light tables and yes it is also possible to develop screens with the sun.
As mentioned, UV curing systems use ultraviolet light to instantly cure the emulsion on the screen, so it is very important to also get max uv on our emulsion. Here we introduce different systems.
Vacuum exposure machines use a vacuum to expose a screen with a positive film. The light source used here is ultraviolet light, usually with a very powerful metal halide lamp, or the new LED light bars.
1) Screen printer exposure DIY Version
Firstly, you can take a powerful lamp, turn the screen upside down with its coating on, fix the film on top and shine the light on the whole thing from above. This is the simplest and probably the most primitive way of exposing your screen.
The result is that the light source emits very little UV. This means that screens developed with this type of illumination are difficult to develop. The light diffusion is not the same everywhere and mostly the film is exposed sideways (underexposed), e.g. fine lines can hardly be developed with this. Also forget CMYK or even index separation, the light source is simply too weak for that.
But as I said, for full color it is possible, and if you only need it as a hobby, it is doable.
2) Table Version Screen Printer Exposure DIY
The second DIY variant are the self-made light boxes, where the light source is usually underlaid with several neon tubes or LED strips. the whole thing is covered with a glass, so you fix the film to the glass. put the coated frame over it, put a black cardboard exactly the inside frame size and weigh the whole thing down so that it lies flat.
This way is better than the first version. Because here the film is pressed somehow, so that the film has direct contact with the coated screen, so to speak. and the light source is stronger. This is how I had coated my first frames myself, but again, for full color prints feasible, but high quality is not to be expected and for CMYK and other fine color operations, not suitable.
3) Direct Sun Screen Printing Exposure
The sun, it is a first-class source of UV!
The procedure is as follows. In your darkroom, flip the coated screen as in DIY version 1, fix the film to it and cover the whole thing with a glass pane that matches the size of the screen frame. It is advisable to fill the inside of the frame with a rigid foam that fits exactly to the inside of the frame. Now cover the whole thing with a light-proof cloth. Take it out into the sun. Hold the prepared frame in the sun and remove the cloth. And that is how you expose with one of the best UV sources we have. BUT how long should you expose? How strong is the sun at the moment? Are there clouds in the way? Unfortunately, it depends on so many things to get a constant exposure every time.
As you can see, there are many variables in this method that we cannot estimate at the time of exposure.
I’ll never forget developing a CMYK separation this way once, and it was top notch.
But seriously, we got lucky and the frames held up until the end of production. Because imagine if the frame had had to be replaced during production. It would have been almost impossible to get the exposure time and UV strength as accurate as the first frame, and we would never have gotten the same printed image again.
Bottom line: yes, you can develop screen printing frames in the sun, but you don’t have durability.
For the hobby screen printer, this may not matter, as this method is also cheap. But if we go to professional screen printing. Then this is a clear NO GO!
Please note
Please note that I only wanted to offer you these possibilities, as a hobby moderately feasible. but if you wanted to operate professional screen printing, I can only advise you against the first three possibilities.
You always have to keep in mind that we want UV radiation. Neon lamps aren’t very UV intensive, and even with LEDs, you have to be careful about how much they emit. The sun of course emits a lot of UV, but unfortunately, it is hard to do consistency here because you are weather and season dependent.
4) Screen Printer exposure unit as Table with a vacuum unit
Screen printing exposure unit as a table with a vacuum unit.
This is the most commonly used method, an exposure table with a vacuum unit.
Classic screen printing exposure unit with vacuum unit
Screen printing exposure unit with vacuum and timer
The setup is also a bit similar to DIY version 2. We have a box where the light source is located,
Glass over the light source, the film and on top of it the frame. Instead of weighing the whole thing down with a weight, we usually put a neoprene sheet over the whole thing, attached to a frame that is lowered onto the glass to make an airtight seal. If you turn on the vacuum pump, the air escapes, and now the glass, film and screen are really tight against each other. Now absolutely no light can penetrate through the sides of the film. This vacuum table uses as light source mostly a metal halide lamp or the newer special UV LED’s.
Exposure Timer
Moreover, most vacuum exposure tables also have a built-in timer. Where you can set how long the exposure should be. So you have a consistency that always remains the same. But even here, it is crucial which light source used. But since it is already about more professional Screen printing exposure unit. Is there at least a metal halide unit used or now also special LEDs or even special neon lamps, with a high UV radiation.
5) Metal Halide Units with a stand
We also have metal halide units that stand on themselves in front of a large, rotating glass frame, which in turn has a vacuum mat attached to the back of it, so that when the vacuum is turned on, the neopreane mat, frame, and film are pressed against the glass.
Die Halogen-Metalldampflampe beleuchtet aus größerer Entfernung. Der Abstand spielt hier eine wichtige Rolle, denn wenn die Lichtquelle zu nahe ist, ist dies nicht vorteilhaft. Ein gewisser Abstand muss eingehalten werden, damit das Licht gerade auf das Glas trifft.
6)The Value of DTS (Direct-To-Screen)
Exposure Units: Revolutionizing Screen Printing
In the evolving landscape of the printing industry, Direct-To-Screen (DTS) exposure units have made a significant impact, revolutionizing the way we approach screen printing. These systems have provided substantial advantages, rendering traditional methods of film positives and manual screen exposure obsolete. Let’s delve into why DTS exposure units have become the printing industry’s game-changer.
Speed and Efficiency
First and foremost, DTS exposure units dramatically increase productivity. Unlike traditional methods that require physical films and manual handling, DTS units operate digitally, accelerating the process significantly. They eliminate the need for films and their associated costs, and cut down on setup times, providing a smooth workflow that significantly reduces production time.
Accuracy and Precision
DTS units offer a level of precision that manual methods can’t match. The units project images directly onto the screens, resulting in sharp, well-defined images. This eliminates the potential for errors during the manual alignment of film positives, leading to improved accuracy in image reproduction. The result is highly detailed and consistent prints, essential in an industry where quality is paramount.
Scalability
As businesses grow, so do their operational demands. Traditional screen printing methods can be labor-intensive and time-consuming, making scalability a challenge. DTS units, on the other hand, are highly scalable. Their digital nature allows them to handle increased workloads efficiently, accommodating larger orders with ease and delivering consistent quality across all prints.
Sustainability
In an era where businesses are more conscious about their environmental footprint, DTS exposure units stand out. By eliminating the need for films, these units reduce waste, making them a more sustainable option. Moreover, since they’re digital, they consume less energy compared to traditional methods, contributing to a lower carbon footprint.
Cost-Effectiveness
While the initial investment for DTS units can be substantial, the long-term benefits outweigh the initial costs. Savings from reduced setup times, lower labor costs, and eliminated film expenses can quickly add up. In addition, the decrease in error rates means fewer wasted materials, further contributing to cost-effectiveness.
Innovation and Flexibility
DTS units cater to the growing demand for innovation and customization in the printing industry. They offer the flexibility to quickly modify designs without needing to create new films, providing an opportunity to meet customer demands for unique, personalized designs with ease.
In conclusion DTS
DTS exposure units have become an integral part of modern screen printing, providing efficiency, precision, scalability, and sustainability. Their cost-effectiveness and flexibility have made them a sound investment for businesses looking to stay competitive in the evolving printing industry. As technology continues to advance, DTS exposure units will undoubtedly lead the way, setting the standard for future screen printing innovations.
ScreenPrint Exposure Unit Summary
The DIY versions shown here are more or less for hobby screen printers. The homemade exposure table could be used for a small print shop on a budget. Just make sure that your light source has a maximum light intensity in the UV range.
The vacuum exposure table is the most common version used in screen printers, and it’s great to be able to control the variables. As a suitable timer is included, the exposure time is reduced. The price depends mainly on the UV power and, of course, the size of the screen they can accommodate. The professional screen printer should definitely keep up with the times. The high price of the CTS should be quickly recouped, it is practical and reduces many variables in screen printing. of course, one should make the calculation, from how many screen frames per day, the whole thing is profitable.
