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Discussion Starter #1 (Edited)
Here is something I wrote for all of those that continue to ask me how to screen print. It's a long read, but it's informative enough to give you an idea of what you're getting into. It's not completely detailed out as to where you'll never have to experiment. Experimenting is always good, this way you know your limitations and your areas you excel. And over time, you'll only get better with more tips and tricks to offer others. Here are the key elements in screen printing:

1. Artwork. The artwork you start art with is important. If you have jagged or grainy artwork, you will reproduce this. There are many art services on the internet that will supply you will screen printing artwork. If you fax them a logo, they can redraw it for you and send you a file in which you can use for the making of screens.

If you can draw the artwork yourself, it is wise to use a vector art program like Adobe Illustrator, Corel Draw or Macromedia FreeHand. Using these programs will ensure that you will have high quality artwork in the end. Photoshop can be used as well, but this is more for full color printing, etc., which is not good to start out with since there are special techniques to master before moving into this realm.

2. Film Positives. When you have artwork that is ready to print, you can print your artwork out on a clear film instead of paper. For every color you have, you will print it out as a black plate on a separate film. For example, if you have a logo that is Red & Black, you would separate the two colors from themselves and print each out, changing the red to black and printing and then printing the black. Each of these would be printed on their own film.

This is simply known as art separations. If the colors are touching in the final version of the logo, then you need to have what is called trap or choke. Basically, it's an overlapping of the artwork by a small margin. This small margin is just enough so you can register the colors so there is no space between them. On the films, you will also place registration marks. These marks usually are a circle with a verticle and horizontal line passing through it. These marks will be on the same spot on each film. This will help you register your colors later.

3. Screen Making. When screen printing began it was called silk screening. The reason for this is, the screens used to be made from silk. Since this is no longer the case (now they are made from polyester), the name changed. A screen is simply a wooden or metal frame that has a fine mesh stretched over and attached to it. This mesh has different counts. Some examples would be 83, 110, 125, 140, 330 and on and various numbers in between. The lower the mesh count, the less detail you can print and the thicker the ink lays down. So it is an artform to say the least in dealing with correct mesh.

The actual process of screen making is quite simple, just time consuming. Capillary film is stilled used but the most common technique is using a light sensitive liquid emulsion. Emulsion can be used under a yellow light so that you still can see what you are doing, but the UV light is filtered out so as not to effect the emulsion. A scoop coater is needed. You pour emulsion into the scoop coater and place it on a vertical screen. Pressing up against the screen and pulling up, you will lay a thin layer of emulsion on the outside of the screen. Turn the screen around and do the same for the inside of the screen. Turn it back around and do it once more on the outside.

Once the emulsion dries, you can "expose" the screen. You need a good light source for this process. I have an exposure unit that can expose 2 20" x 24" screens at a time. It has a halogen light along with 2 black lights to help diffuse (or even out) the light. The exposure unit is basically a box with a glass top and a lid that has a black matte and a vacuum frame. The light source would be contained in this box.

To expose a screen, taking the film positive you created and place it on the glass top with the right reading being up. Then take the dried screen and place it on the glass top with the film positive under it. The screen mesh will be touching the film positive. When you close the lid, there is a vacuum frame that will suck all of the extra air out of the frame. This vacuum frame will pull the matte close to the screen frame. This is essential for a crisp image to be burned into the screen mesh.

At this point, the length of time will be dependent on your emulsion and light source. This is something you can talk to your emulsion supplier about. It’s really a matter of testing. Most problems occur in this stage, so it is critical that you understand this process through testing, training and trial and error. The better you are in this area, the better your prints will be. I currently use a 3 minute exposure time because of the combination I use, but this will vary as already mentioned.

Once the image is exposed into your emulsion, you can take the screen to a washout booth. Lightly spray both sides of the screen with water. I garden hose with a sprayer on the end works well for this procedure. You do not want a lot of pressure but you do want some. After waiting for a couple of minutes, you can go back and begin spraying your screen with water. Spray on the outside of the frame, or the side that was touching the film. The inside will naturally be softer because the light had to shine through the emulsion to get to that side. As you spray down the screen, you will see the image on your screen. What happened is, wherever there was black on your film, the light did not shine through. Since the light could not expose the emulsion, it remained water solulable. Wherever the light shine through the emulsion, it hardened and will not wash away. Let the screen(s) dry.

4. Printing Press. Choosing a printing press isn’t nearly as critical, although you are looking for a quality press. To be honest, you may want to stay away from all-in-one units and similar machines. They are a waste of money. Even though you can print just as good of a print with these machines, they are costly and they slow your process down. When I started, I was told a 4 color 4 station press is just about all I needed. They were right. Very rarely did I ever need to print anything more than a 4 color design. Later, as I grew, I purchased more machines that allowed for more colors. But the first 5 years of my business, I believe I had 1 6 color job and 1 5 color job. So it wasn’t critical for me to spend more money on a 6 color machine. What you are looking for in a press is a solid frame, micro registration and rotating platens. Outside of this, you don’t need much more than that.

5. Conveyer dryer and flash unit. To actually cure the ink, you need a heat source to reach 320 degrees for your ink. If you can reach 320 degrees in 1 second, it’s cured. If it’s 10 seconds, it’s cured. As long as it reaches 320 degrees, you are good. A flash unit is a unit that you place over your platen (arm that you place the shirt on). This flash unit is meant to flash the ink just long enough where it is not cured and it is not wet. This will allow you to print colors on top of colors if needed, and you will need it! Many people use these units to cure their shirts. This is not wise. If you have a flash unit over a platen, it has to reach 320 degrees to cure the ink. This heat will eventually warp your platens, causing printing problems in the long run. It will also heat your platen up enough that when you put another shirt on it and print, it will semi cure the ink in your screens, causing a clogging and poor printing. So buy the flash unit and use it for it’s intended purpose, to flash the ink, if you have to. If I print a single color on a shirt, I will not use a flash unit at all. If it is white printing, then I will. The reason for this is, you would print white on a shirt, flash it, then when the shirt comes back aroudn to you, it needs a second print. This gives you a good vibrant white. If you are printing a color on a dark shirt, you would also print a white underbase, flash it, then print an exact image with a different screen over top of it with the color you need.

The conveyer dryer is needed to increase your production. When you finish printing a shirt, you pull it off of your platen and place it on the conveyer dryer. Basically, it’s a dryer that has a belt on it that goes through a tunnel of heat. When it comes out the other side, it is cured. There are temperature strips that you can place on the shirt to run through the dryer and make sure the heat and speed setting are correct. Raytek also makes a heat gun that when the shirt comes out, you point the laser beam at the ink and it will give you a temperature reading. Remember, 320 is the magic number!

6. Inks and miscellaneous. The ink you will use is a Plastisol ink. There are so many manufacturers and types of inks, it’s good to find one and stick with them. I can give you suggestions of what I feel are good, but it’s all up to you in the end. You will also need squeegees. A squeegee is basically a handle with a rubber blade on the end. This blade is what you use to push or pull the ink through the screen and onto the shirt. There are so many miscellaneous items that it would be good to talk to a supplier about what you need to get started.

7. Screen prep and registration. Your scoop coater cannot reach all areas of the screen, so you want to tape out the areas that did not have emulsion. There are special tapes made to do this, but packing tape works well if you remove it right away when you are finished. Simply tape the inside and outside of the screens wherever the emulsion did not cover. If you have a one color design, placing the screen on your press is quite simple. If you have more than one color, this is where the registration marks are needed. After placing your first screen on the press, you would do a test print. Place some ink on the screen and rest a squeegee on the frame close to the head. Pull the ink across the screen and onto the shirt. Next, take your second screen and place them on the next head. Align the registration marks on the screen to the marks on the print you made. Once in place, you can lock them in and adjust the micro registrations if necessary. Once locked in, do a test print. If everything is registered, you can tape up the registration marks on your screen and you are ready to print.

8. Your first print. You will be working upside down when you print t-shirts. The collar will be closest to you. After placing the shirt on the platen, pull your screen down. One thing I did not mention was off-contact. If you look between the shirt and the platen, you should have a gap. This is called your off-contact. You need about 1/8” between the screen and the platen. This will give you just enough room to make a print and allow for the screen to snap away from the shirt. This gives you a clean print. Some people will push their squeegee and others will pull. Whatever is comfortable to you is best for you. Personally, I’ve always pulled my squeegee. This means that when I pull down my screen, I grab my squeegee and pull the ink towards me. You want to have the sqeegee at an angle, but not too much. A 70 - 80 degree angle is good. If you go too much of an angle, you will get a heavy print and it won’t look very good. If the angle is a 90 degree, then you won’t get the proper pressure, giving you a light print. The good thing is, if the first print does not work out for you, you can print it again, right over top of it. The registration of the machine will be the same so even if you rotated the press and came back to it, it would still print good.

As with anything, practice is what is needed. Make sure that whatever you do that works, keep it consistent. A firm grip on the squeegee, a consistent angle and a quick stroke will give you a good print. When you find that print, keep it consistent. Good luck!

I may have missed out on some simple tricks and techniques, so if you have questions or are stumped, you can contact me at any time!
 

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Thanks DTG, that was a great post.

How messy is this process? How much ink are we talking about putting onto the screen? I'm just curious. I could see myself covered in ink, all over my clothes and in my hair and probably on the walls and ceiling.

Also, I know you can clean and use a screen over again, but how long do they typically last? How many times can you drag the squeegee over them before they are no longer good to use?

And, if you were to start out with a 4 color manual press, and a flash unit and a conveyer dryer, how big of a room do you need to have this screen printing setup?
 

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Decal_Designs said:
How messy is this process? I'm just curious. I could see myself covered in ink, all over my clothes and in my hair and probably on the walls and ceiling.?
Plastisol ink is an oil an plastic mix.... That means it is your ENEMY.... even a tiny tiny speck of it will travel all over and end up on you, the t-shirts, the sides of the screen...etc.

Great care is taken NOT to get ink on you.... it usually happens when adding ink to the screen with your spatula.... then it travels faster then a flu bug in a subway..

during a run I constantly am checking my hands for ink.... everytime i add ink Check my hands.... when i put squeege down check my hands before touching shirt check my hands etc etc... it becomes second nature after awhile... Plastisol will not dry on its own becasue of the oil you can get ink on you from touching a screen that you used last week... That is why such great care is taken NOT to get it on you in the first place.... however it happens sooner or later anyway... thats why the spot gun is kept close by.... all this sounds like a hassle but it really is not.... If you pay attention and check check check it isnt a problem. If you are sloppy....well..... your in for a long day....
 

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Discussion Starter #6
How messy is this process? How much ink are we talking about putting onto the screen? I'm just curious. I could see myself covered in ink, all over my clothes and in my hair and probably on the walls and ceiling.
It's pretty messy at times. Once you print for a while, you will get the hang of keeping it clean, but it's never truly ever clean. I used to destroy my clothes and my wife would say why don't you just wear an apron, so I got a really big one and next thing I know, I've got ink on my back! Go figure! A good spot cleaning gun can save you alot of money in clothes, just make sure you zap it right away before you start smearing it all over the place. The messiness of it all is one reason why I believe digital printing is definitely hitting the market hard right now. (wink wink)

As for how much ink you put on the screen is dependent on the image size and how many prints. You get used to it and you are usually able to figure out just about exactly how much you need.

Also, I know you can clean and use a screen over again, but how long do they typically last? How many times can you drag the squeegee over them before they are no longer good to use?
Great question. I run both manuals and autos and my auto will run wear out a screen quicker, but I've printed over 5,000 shirts on the same screen with no problems.

And, if you were to start out with a 4 color manual press, and a flash unit and a conveyer dryer, how big of a room do you need to have this screen printing setup?
I started a similar sized operation out of a one car garage with room to spare.

Hope this helps!
 

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i have a one screen manual press set up in my bedroom, it's awesome, all grassroots style. I just wake up, screen and dry some shirts when i want, change screens/inks. i love it. you can use a screen a bunch of times, but I like to keep things fresh and only have 4 screens (3 now after one refused to wash out) and wash them out and put a new image. screen printing > a lot of stuff lol
 

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also, about the emulsion part, it's best to lay the screens down with side of the screen that would touch the shirt facing down, and the part you squeegy facing up so the emulsion forms a gasket on the shirt side. this way, when you squeegee, u dont scrape the image, but just the screen, and the image stencil is on the shirt side, out of harms way. well that's just me, I find that helpful.

Ohyeah! also, leave a fan on it to dry over night!! i've mest up many a screen because i thought it was dry overnight without a fan, and the screen dried perfectly on the outside, but not towards the middle, so when i washed it out, the whold image just blew off with the pressurized water! so leave a fan on it overnight, it'll dry awesome, and save you time and headaches. :)
 

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Discussion Starter #10
Most likely the reason why your screen did not wash out was you probably used an emulstion reclaimer or remover and sprayed it on and let it dry. You should never let the reclaimer dry on the screen or you will not wash it out except with a 3000 psi pressure washer (and even at that, it takes a while). Spray some reclaimer (or remover) on the screen, take a scrub brush and work both sides of the screen. Wait a minute or two and then use a pressure washer or high powered water source to remove the emulsion.

Also, when you want to burn an image in the screen and wash out the unexposed emulsion, do not use a pressure washer. That will not do good and most likely you will not get the good results you are after. If it's taking a while to wash out an image with an ordinary water source like a garden hose, then you most likely are over exposing your screens.

What I like to do is spray water on both sides of the screen. On the print side, I will usually take my hand and rub it over the image. If you under exposed the image, quite a bit of emulsion will be released on to your hand. With a properly exposed image, very little, if any at all, emulsion will be released on your hand, but you will see the image break down quickly. If this works properly, just spray a little more water on both sides and wait a couple of minutes. Then take a hose and spray the image out the rest of the way. You don't want a lot of pressure at this point. You might want more pressure for halftones and fine lines, but normal pressure works for most of the time.

Good Luck!
 

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yeah, that's why i screwed the screen up i m sure, cause of the reclaimer being left on too long. I do want to try and finish recmaiming it because there's some emulasion left like in small patches like a plague haha, like not too much, but still unusable, but that was after an hour or so worth of spraying, washing, scrubbing, and so forth. I'm pretty much out of the reclaiming chemical now because of that one screen.
 

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When choosing a light source I have had the 'pleasure' of trying black lights - oops wrong type (filtered) and 'grow' lights ( I think they were filterd too). I have a pair of heat lamps the McDonalds type - I am about to try out but just in case I bbq myself - is there an easy way to find the specific type of lamps with the high UV we need? I have been using the sun but with record rains and trying to get a 'control' process that is so very necessary its a little too much hard work for the exposure process......
Thanks
 

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When using Photoshop CS, do I need an expensive Plug-In for color separation, or can i do this somehow without the plug-in?

Thanks
 

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For color separation can't you just save each color in a new layer than just print each layer one by one? don't forget you registration marks. I use Corel but I have heard others say you can do this.
 

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I made a box with a piece of glass on top and a construction light on the bottom. turn it on for 3 minutes and the image washes out perfect with a sink spray hose thing without too much pressure at all.i use a ulano DLX emulsion. heres a print i did with 3 colors for my band using photoshop for color separation
 

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the way i separate colors is to adjust the contrast, select color range, pick the color you want to separate first then after that, go to select/ inverse then delete. after that grayscale it then bitmap.
 

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Discussion Starter #19
No, problem, that's why I posted it, I'm glad I can help.

The only thing is, I'm amazed it was over a year ago I posted this!
 
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