Large Scale Press Questions...

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questor
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Large Scale Press Questions...

Post by questor »

I am interested in creating and screen printing large scale signs for a local political campaign in the upcoming elections. I have several questions whether to make the screens and press myself or if I am better off buying pre-built screens.

The signs need to be 3' x 6' or 4' x 8', printed 2 color + white base on both sides, for continuous 6 month outdoor use. This screen printing setup would likely only be used 2 times per year and stored the rest of the time, so a semi-portable press is needed.The materials to be used will likely be Coroplast or Polycoat. I will likely use Coroplast inks.

My questions are:

1.) Which screen press model and manufacurer makes stable units that will work properly with these 3' x 6' or 4' x 8' sizes that I need? Do I need a larger size 2-station press to handle the heavier size/weight of the larger screens?

2.) Can I make or modify an existing smaller size press to work properly with large size screens? What are likely long-term hardware problem areas of these types of presses?

3.) How difficult is it for me to make my own *durable* large scale screens out of wood or aluminum? What mesh size is recommended for use with Coroplast inks?

4.) Can you refer me to an Internet websites that detail how to make these large scale signs on a budget?

Thanks, Steve
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Post by DTGPrinting »

If you have never printed on Coroplast, espcially that big, I would find someone to do it for you. Coroplast printing isn't the simplest to print. I used to own a graphics press and printed coroplast. The business wasn't there for me to continue so I sold the machine and when I get requests, I print it by hand.

Again, though, it's a different type of printing and there is a very large learning curve. Dealing with inks, screens, pressure, etc, etc.

If you go the route of printing yourself, I can give some tips once you get going, but there are companies that are extremely fast, excellent priced and have incredible quality just waiting to sell wholesale.
Jerid Hill
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questor
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Post by questor »

Thanks, for the reply...

In this area the local printers tend to overcharge for last minute print jobs. As we all get closer to Election Day, the printers get filled with last minute orders that delay delivery, particularly on these large political signs.

Since I work for a campaign now and will continue to do so in the future, I am trying to lower our overall costs while increasing the quantity of signs available on last minute schedule. I have some experience in the magazine printing industry, but not with smaller screen printing.

I agree there can be a big learning curve, but I am willing to take the risks.

Thanks, Steve
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Post by DTGPrinting »

I was thinking of a company more like Stouse. They are great at what they do and they are fast.

If you need the control of printing inhouse there are a few things you must adhere to.

You can use Nazdar's Corogloss inks. They are made specifically for coroplast and they cover really well. If you have a hotter climate or a higher humidity, you may need to add some retarder. When using the retarder or thinner, you shouldn't use more than 15% of either or both combined. Keep it under 15% and you'll be fine.

The ink shouldn't be too thick but obviously not too thing. I would say the thickness of molasses or even slightly thinner. When using ink this thin, you need to use a higher mesh count. I usually use a 230, it holds detail really well and it keeps the ink from seaping through making a mess.

When printing, you want to flood coat the screen. Not like you do using coroplast, but with conventional inks, you need to flood the screen with a bit of pressure. This pulls any excess ink off of the top of the image. If you flood coat it and leave ink in a heavy deposit, the weight will cause the ink to push through the screen when just sitting. This will cause a big mess when printing. In addition to flood coating, you should be printing 4 - 5 pieces per minute. This gets difficult when printing larger pieces. You should have someone helping with the larger signs. As soon as you print one piece, lift the screen and flood coat it, then change your sign out.

You should also have some drying racks. Since they are air dry, the racks will help with the flow of air and save space.

Now for some of the things you need to repeat with each print run. Print with the flute. Some people will print against the flute, but the problem with that is the image can get distorted somewhat, because you are trying to print with a very thin ink and the pressure of the squeegee going on a bumpy surface can cause a heaviness in areas that you don't want. When you print with the flute, if you don't print with enough pressure, you can have white lines form in the recess of the flute. So it's a matter of getting the right pressure to keep clean, sharp lines.

Squeegee pressure and angle need to be consistent. You want a medium to hard durometer sqeegee that is sharp. Keep the angle higher so it doesn't push exess ink in the screen. You will get a feel for it with practice.

As for colors, this type of printing can only have one color printed at a time, otherwise you will definitely have a mess. That's about it for now.

Good luck!
Jerid Hill
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http://www.screenerschoice.com
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andymac
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Post by andymac »

WE have presses that would work perfectly for this and I have a lot of experience printing coroplast, so could help you get going. Go to our website and have a look at any of the Jaguar line of large format screen presses. Cheapest are the clamshell one arms, then springlift parallel, and the air lift parallel. prices are listed under 'news' section for now.
My 6 year old grandson can print large format on the airlift, it's easy to use and operate, you don't have to be a screen ape to run jobs.
For production tips & assorted ramblings read SHOP TALK monthly in Screenprinting magazine. Visit www.squeegeeville.com for screenprinting information and classes. Visit TMI Screenprinting Equipment Booth 1580 at SGIA 07.
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