Will some of you more experienced screenprinters answer a few questions please?
How are halftones screenprinted? Do you do them the same way any other screenprint?
I've only been asked to print up to 4 spot colors. I'd love to know how to get more creative. I've heard of wet on wet technique, but have no idea how that would be accomplished.
Is there some literature out there that you would recommend to help expand my knowledge of screenprinting?
Also, I've always used capilary film purchased from Press a Print. How many of you are using emulsion?
Is it easier? Does it make a bigger mess? I'd like to hear thoughts and recommendations for exactly which emulsion people are using and where they are getting it.
Thanks a lot for the information. It's nice to know I can come here to get good information.
__________________
Pete Munson, SQL Promotional Products www.sqlprints.com 888-657-3631
How are halftones screenprinted? Do you do them the same way any other screenprint?
Yes. There are some things youu have to consider to get the best print.
Higher mesh is best for optimum burn and dot gain control during printing.
depending on dot size your mesh count might vary.
Normal manual priting dot size on average is 42 - 55 dpi. best mesh for these are 196 - 305
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I've only been asked to print up to 4 spot colors. I'd love to know how to get more creative. I've heard of wet on wet technique, but have no idea how that would be accomplished.
Most wet on wet prints use but registred art. Essentially you want all your inks to be close to the same viscosity/thickness. Most prints will warrant smallest print area to the largest yet if mixing colors on press this may vary.
This helps to minamize ink buildup on the bottom of sequential screens
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Is there some literature out there that you would recommend to help expand my knowledge of screenprinting?
Sign up for all the industry magazines. Each issue of all the mags has tons of valuable info. you can find a buch of links here U.S. Screen Print and Inkjet Technology in the industry links section. Impressionsmag.com, Printwear.com, Screenprinter mag
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Also, I've always used capilary film purchased from Press a Print. How many of you are using emulsion?
Quite a lot use regular liquid emulsion. It is actually cheaper than Cap film especially if your using lots of screens.
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Is it easier?
There is a learnign curve to coating yet once you learn it its easy as Pie
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Does it make a bigger mess?
Depends on you. At first its a lil messy until you learn how to use it.
Ulano is a great emulsion. I would suggest contacting them, discussing your set up, Exposure unti, etc. and let them reccomend the exact brand to use.
We use Ulano RLX and love it. have been using it for over 10 years. There are others by Ulano just as good.
Will some of you more experienced screenprinters answer a few questions please?
How are halftones screenprinted? Do you do them the same way any other screenprint?
I've only been asked to print up to 4 spot colors. I'd love to know how to get more creative. I've heard of wet on wet technique, but have no idea how that would be accomplished.
Is there some literature out there that you would recommend to help expand my knowledge of screenprinting?
Also, I've always used capilary film purchased from Press a Print. How many of you are using emulsion?
Is it easier? Does it make a bigger mess? I'd like to hear thoughts and recommendations for exactly which emulsion people are using and where they are getting it.
Thanks a lot for the information. It's nice to know I can come here to get good information.
The question 'how can halftones be printed' is easily answered as - just image that they are tiny spots of color. Actually, this is a true statement. Halftones, once printed to a film positive are no different to print than tiny little dots of spot color. Now, the rest of the story...
1. You will need to have halftones printed to the film positive at the right size and angle. The size will depend on the mesh used (or vice versa). Simply divide the mesh count by 4.5 to find the right number of lines per inch for the halftone or multiply the line count of the halftone by 4.5 to find the correct mesh.
If you are using a 110-80 mesh then the formula is simply ...
110 / 4.5 = 24 LPI (this means that there will be 24 dots per linear inch in your halftone.
If you are given a halftone to print and it is 45 LPI then the formula is...
45 x 4.5 = 202.5 and thus you could use either a 195 mesh or perhaps a 220 mesh.
As for angles, the best angle is one which does not create a moiré when printed. Most screenprinters find that the best angle is 22.5-degrees. It used to be that we used differing angles for each color, but about 12 years ago many started using 22.5 degrees for all angles and found that this worked quite well.
Wet-on-wet printing is the preferred printing technique in the garment printing segment of the screenprinting industry. Other items will not accept the wet-on-wet technique. As long as you are using a good press, printing on light garments, have enough tension and the correct off-contact you should be fine. You will use a butt register on your colors, i.e. they will butt up against each other and not overlap. When printing on dark garments, where you will print colors on top of a white underbase you will experience more problems that can be rectified with a new and improved printing technique.
Before we get too much into the printing technique, I must say that I was worried when I saw that you were purchasing your capillary film from Press-a-Print. This means that you may be using their all in one printer and if so, you may not be able to do wet-on-wet printing well, if at all. The reason boils down to two things, tension and off contact, neither of which is easily adjustable on the Press-A-Print press.
Tension relates to the tightness of your mesh. You will need good tension levels of at least 20 Newtons per centimeter squared (20Ncm2) in order to pull off wet-on-wet printing. The reason is that ink will adhere more easily to screens that are tensioned less than 20Ncm2. You can attempt to print with less tension but you may find that you need to put down more ink on the first color in order to keep from driving it into the shirt with each additional color, i.e. you will need to adjust the viscosity of your inks or the amount of ink that you print via a more open mesh count on the first color.
You should always strive to print the color with the smallest area of ink coverage first and then work up to the color with the most coverage. White or the lightest color may have to be printed last to maintain its brilliancy. I very much dislike using a flash gel unit, so I actually prefer a 'crush white' on dark garments, or when I must print a white underbase. I print a slightly heavier base of white than I would normally to attain brilliancy and then print the other colors directly on top of this without flashing the white underbase. The next color, if printed directly on top of the 'crush white' will push it into the garment slightly and decrease the brilliancy. By pre-engineering the printing technique you can achieve a very nice look without the need to flash.
If you have tension levels of 20Ncm2 and above you should not have a problem with ink build up on the back of your screens. Those printers with less tension will constantly be stopping to wipe up the backs of their screens. This is a very common problem with low tension screens, where the ink must be pushed through the mesh with such force to overcome the extreme off-contact that the ink extrudes through the mesh openings and creates a mess on the bottom of the screen.
Off-contact is the distance from the bottom of the screen to the top of the substrate. You need the correct off contact to print wet-on-wet, which varies with tension. With tension levels above 20Ncm2, you will find that an off-contact distance of about 1/8-inch will be sufficient. As your tension levels drop, you will need to increase the off-contact distance. If your mesh tension is so low that you have to increase your off-contact to anything above 3/16-inch, you may want to consider replacing the mesh on your frame.
It is this reason why most printers eventually shift to retensionable screens such as the Newman Roller Frames, however, if you own a Press-A-Print, you will not be able to use the Roller Frames as they will not fit into the system.
I cannot make a recommendation on education since I own a screenprinting school and the rules of the forum forbid me to enter into a discussion that might appear to be self promotional.
As for emulsion versus capillary, you will find that both have their place in the screenprinting industry. As a rule, capillary film is 5 to 10 times more expensive than direct emulsion. So, cost is a big factor to most.
Liquid direct emulsion can be easily coated onto a screen by those who have done it a few times in about the same time as applying capillary film. It is not necessarily a messy task, but I have seen people who can make a mess of just about any task given them. I have been using direct emulsion for more than thirty years and have never spilled anything more than a drop and I quickly wiped it up with the corner of a paper towel.
Joe Ulano invented liquid emulsion and Ulano has the leader for many years in the emulsion business. Joe has since passed on and the company sold a few years ago to KIWO, which has since become a world leader in emulsions. The original Ulano formulas have not been altered and the company still makes a very good emulsion.
What you are looking for in an emulsion is a good solids content, which will make a longer lasting stencil with less problems. You are also looking for an emulsion that is not effected by humidity, good mesh bridging, edge definition, resolution, resistance to your ink system, mechanical resistance, produces a good Rz factor, and a good emulsion over mesh ratio. Any thing less than this and you will have problems somewhere.
You can liquid emulsion for $20 to $80 a gallon. The $20 emulsion is most water and filler and your stencil will breakdown quickly. You will spend an enormous amount of time painting out pinholes and cracks in the emulsion. Good emulsions usually start at about $50 a gallon and you should be able to coat about 100 screens from a gallon of emulsion, making your cost per screen between $0.50 and $0.80 a screen. I always use the very best emulsion on the market and pass the cost onto the customer. I have never had anyone complain about an extra $0.30 on the total order.
Hopefully, this will answer your questions. You can always feel free to ask me anything as I very much enjoy helping others.
I sincerely hope that I have not offended anyone with my opinions.
Capillary film is a lot easier for a beginner to get right. Liquid emulsion has a very steep learning curve. You'll do a lot of cussing and want to quit before getting a decent stencil with liquid emulsion. Whereas, with capillary film, you will make a better stencil on your first try than you probably will get on your 20th try at liquid emulsion.
But like they said above, liquid is cheaper than capillary film. Bill said above that liquid is about .65 cents a screen, whereas capillary film is about $2.50-$3.00 per screen. But when you consider that if you use an average of 2 screens per order, you are talking about a cost difference of about $4 per order, which is really only a fraction if you are going to make a few hundred dollars per order.
Another consideration is your time. It takes longer to prepare a screen using liquid than it does to use capillary film. You need to ask yourself, "How much is my time worth?" Is it more important for you to save $4 per order, or to save 30 minutes per order? For me, my time is worth more than the $4 savings. And the confidence of knowing I'll get a rock solid stencil every time is also a big factor for me.
Granted, if you are a big shop that does many jobs per week, then it may be worth putting in the time to develop skill of using liquid emulsion. I'm not that type of printer. So for me, a printer who prints probably a job a week, capillary film is the way to go.
Liquid emulsion has a very steep learning curve. You'll do a lot of cussing and want to quit before getting a decent stencil with liquid emulsion.
I still remember the first screen I coated. It went perfectly. It's really not hard, you just need to be careful. Occasionally I screw up and spill some emulsion (always because I'm in a hurry), but it's just nowhere near as hard as people convince themselves it will be.
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Originally Posted by rusty
Is it more important for you to save $4 per order, or to save 30 minutes per order?
How the heck can you save 30 minutes per order when it doesn't take anywhere near 30 minutes to coat two screens?
I still remember the first screen I coated. It went perfectly. It's really not hard, you just need to be careful. Occasionally I screw up and spill some emulsion (always because I'm in a hurry), but it's just nowhere near as hard as people convince themselves it will be.
But you are a genius . I coated probably 50 screens and none of them ever came out anywhere near as good as the first one I did with capillary film. I even went to one of Richard Greaves seminars and did exactly what he said, and they still came out lousy. Richard was the one that told me to try capillary and I've never looked back since. There are so many variables in involved in getting a good stencil out of liquid emulsion, it just takes a long time to figure out what they all need to be for your environment. If you made a perfect screen the first time, I can assure you that you are the exception and not the norm.
Kind of like Albert Pujols saying, "hitting a HR is easy, just go up there and swing the bat, and the ball flies over the fence..." Yeah right, Albert .
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Originally Posted by Solmu
How the heck can you save 30 minutes per order when it doesn't take anywhere near 30 minutes to coat two screens?
For 1, it saves me at least that much because I never have to recoat a screen that didn't work the first time . And you don't have to mess with mixing the emulsion. You don't have to wait a day for the bubbles to rise out of the emulsion. You don't have to clean up after coating. I always hated cleaning the scoop coater. The capillary film dries much quicker than emulsion. You can be ready to burn a capillary film in a matter of minutes where liquid emulsion takes hours to dry. And of course, all the cussing takes a lot of time with the liquid
Capillary film is a lot easier for a beginner to get right. Liquid emulsion has a very steep learning curve. You'll do a lot of cussing and want to quit before getting a decent stencil with liquid emulsion. Whereas, with capillary film, you will make a better stencil on your first try than you probably will get on your 20th try at liquid emulsion.
This may be true with a cheaper emulsion but I showed my cousin how to coat a screen with ulano qtx and he did it perfect on the first try using a scoop coater.
The debate over Capillary vs. Direct emulsion will be going on long after I'm dead, but there are clear facts that can help you to make your choice.
1. Capillary film dries faster because the water in the mesh that is absorbed with capillary action is all that has to evaporate, not the 65% water content of the average emulsion.
2. If a screen coated 1x1 works for you and you are satisfied and it gets the job done, I see no reason to invest more money for capillary film. If an old pickup truck works for you, stick to your guns, but if you need to go faster or carry more load, you will need to upgrade or you can't compete.
3. Yes, capillary film dries faster, but you don't have to sit there doing nothing while it dries. It dries all by itself. All arguments about drying time are eliminated if you coat your screens before you need them and have them on a rack, ready-to-expose. No waiting.
4. If you want a specific Emulsion Over Mesh (EOM) thickness. If you want a smooth gasket for printing the best half-tones - capillary film is more reliable.
5. If Bill Hood and I were both magically transported to your shop, we couldn't make a better screen with multiple face coats (because of the effect evaporation has on the stencil surface), than little Jennifer making her third screen with capillary film.
6. I hate cleaning the emulsion coater.
I endorse the philosophy that it is more important to make money printing, than save money in the screen room. You will never make a good living for yourself focusing on how well you are saving money in the screen room (it helps to pay attention of course), you make money selling printed shirts.
Ask yourself - Does it help you sell shirts? Does it help you print faster? Does it help you print faster?
__________________
How are you measuring? retired Ulano Technical Support Screen printing since 1979 - SGIA Academy Member
Last edited by RichardGreaves; April 17th, 2007 at 06:18 AM.
If you made a perfect screen the first time, I can assure you that you are the exception and not the norm.
My first was actually better than my next few I was determined the first would be perfect, then I got a little lazy You're right that people normally mess up a few at first, but I don't think it's that hard. Each to their own though.
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Originally Posted by rusty
You don't have to wait a day for the bubbles to rise out of the emulsion.
That does suck if you notice too late that you've run out/are about to run out.
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Originally Posted by rusty
You don't have to clean up after coating. I always hated cleaning the scoop coater.
I must say I agree with that too. I don't know why, but that's one of my least favourite shop jobs too.
This may be true with a cheaper emulsion but I showed my cousin how to coat a screen with ulano qtx and he did it perfect on the first try using a scoop coater.
If an experienced screenprinter had come to my house and showed me how to create a good screen using my exposure unit and my drying room, I'm sure I would have had a lot better luck. So if you showed him how to do it your way, using your variables, then yes, it's very easy to learn how to pull the coater across the screen. But there's a lot more variables involved than just pulling a scoop coater. The environment of the drying room also has a lot to do with your success. For example, using the exact same procedure in Chicago as in Dallas will present different results if the drying room environments are different. Humidity has a big effect on screen coating.
If any of you haven't tried both liquid and capillary, I'd suggest trying both so you can compare. Before I tried capillary, I had no idea what a good screen really looked like, so I didn't have anything to compare it to. So for the original question, I'd suggest trying both and seeing which gives you the best results for your money.
Thanks for your comments Richard. And thanks for all your help in the seminar you taught in Fort Worth last year. I was about ready to throw in the towel until you pointed me in the right direction. You are very kind to share your wisdom with the rest of us.
Last edited by rusty; April 17th, 2007 at 07:52 AM.
Help with screenprinting halftones 
. I coated probably 50 screens and none of them ever came out anywhere near as good as the first one I did with capillary film. I even went to one of Richard Greaves seminars and did exactly what he said, and they still came out lousy. Richard was the one that told me to try capillary and I've never looked back since. There are so many variables in involved in getting a good stencil out of liquid emulsion, it just takes a long time to figure out what they all need to be for your environment. If you made a perfect screen the first time, I can assure you that you are the exception and not the norm.
I was determined the first would be perfect, then I got a little lazy 
