Question about Screen Printing

[Chief.]

Here's the deal: My dad is thinking about running a small screen printing business out of his office he owns in town. Since my plan was to graduate college and run my own screen printing business, this will work out well.

Now, if anyone here is in the screen printing business, I'd like to know what kind of equipment is needed. We need to able to print designs onto mugs, pens, t-shirts, mousepads, etc. We're planning on going to a 3-day training expo in Chicago in August, but I'd still come to you guys first for some information. So for anyone with experience in this business, I need some advice and tips about equipment that you use. Your help is greatly appreciated.

[bear69designs]

I've done a little screenprinting in my time. I can throw out some items for starters... maybe there are some real experts here that can tell you more.

If you'll be running a small place, then you'll probably be doing garments for starters, but this could also include the mousepads or anything else flat that you can lay down on the carousel. Doing objects or materials with more relief (like the mugs, etc.) takes more specialized equipment with which I have no experience.

THE BASICS

I've worked in small places that focus primarily on garments and use manual carousels. The carousel is a multi-station machine that consists of a small number of small aluminum or wooden tables (of which the position, height and inclination are adjustable). Above the tables are armatures that the screens clamp into, and these are moveable (usually spring loaded but could be hydraulic). Your substrate (material to be printed on) lies on the table, and the screen is lowered to make contact with it. The screen is filled with ink and the operator uses a squeegee to force the ink through the screen onto the substrate. The reason the carousel has multiple stations is so that stations can be rotated out of the way and dried if neccessary while work continues on another table.

If you do a single-color print then after the ink has been applied the garment (or whatever) is removed and sent through a tunnel drier, which is basically an oven with a conveyor. The speed and temperature are adjustable based on the type, amount and composition of the ink used. If you are doing multiple prints, the just-printed table is rotated under a small drier which is basically a heater on a stand. The garment is left under the drier while work continues on another table.

SCREENS: WHY, WHAT & HOW

The screens are created using a photochemical process which is now pretty old school. You will probably create your art designs with a vector graphics program but they will need to be printed out to create a camera-ready positive. You can also do art with pen and (india) ink. If you do it on computer you'll either need a printer that will print a format large enough to make the image the size you need or you will have to manually composite letter-sized pages to make your positive. For single color prints you need only one positive. For multiple colors you need one positive for each color. (You can also do four-color process screen printing if you are ambitious.)

Once you have your design executed as a positive it is ready to be shot. The positive is either placed on a copyboard in front of a large camera or laid down on a camera that is sort of like a scanner or copier bed. This exposes the image onto film and creates a negative. Then the negative is used to expose a screen.

The screen is a mesh of wire, held in a wooden or aluminum frame. You can buy them or make your own. If you do much work you'll have to repair them yourself from time to time. They come in varying degrees of fineness. The finer the screen, the smaller the wholes in the mesh, and the better the resulting image. The technique is called "silkscreening" because for centuries people did the same thing using fine silk cloth as the mesh.

The screen is coated with a photoreactive fluid, which hardens at room temperature after a short time. The screen is placed on a lightbox, with the negative. Weight or vacuum is used to ensure good contact between the two. Light passes through the clear areas of the negative, degrading the fluid. After a certain time (determined by many things, but discovered easily enough by trial and error) the screen is removed to a spraybooth. A pressure wand is used to spray the screen and remove the areas of fluid that have been exposed, leaving a positive on the screen. After the screen dries at room temperature it is ready to be clamped into the carousel.

After the screen is used you can clean it with an ink knife and a mild solvent and store it for reuse (if, for example, it has a popular school logo that you will probably reuse later), saving time and labor. Or it can be cleaned with a strong solvent and have all the ink and fluid removed, then dried. The clean screen is then ready to be used again for another job.

Screens can fail. The frames can break, holes can wear in the mesh, ink and fluid can harden in them and refuse to come clean, and the mesh can come loose. You can repair these things yourself or outsource it. You can also easily outsource your filmmaking.

"HIGH TECH"

You can do four color process, but it makes registration of the different prints even more critical than if you are using single spot colors. You can also use automated carousels, which require only two operators to load and unload garments and make basic inputs. Such setups are pricey.

THE ART

The single most difficult aspect of screenprinting, and the one thing that makes an experienced screenprinter so valuable, is the installation of the substrate to the table. It can take a lot of reps, sometimes over years, to achieve speed and accuracy when throwing t-shirts on the tables and getting them straight, wrinkle-free and positioned correctly. Every other aspect of the process is pretty easy to learn, and even menial. Working the table is where the art is, and if you start your own place expect to spend many, many hours wrestling with shirts learning the skill. You will definitely look for an experienced screenprinter eventually, because once you learn how to do it well you'll be scared to try to teach someone else!

There is also a bit of an art to judging ink dryness: on multiple impressions the ink must dry enough to not smudge or run when the next impression comes down. Wooden frames and tables are less thermally conductive than aluminum, and so cause garments to dry more slowly. Efficiently executing multiple impressions and trying to knock out 100 t-shirts an hour comes down to getting in a rhythm. Too little time under the heater and the ink will be too wet for the next impression. Too much time under it will scorch the ink, causing it to bubble, or, worse, burn the garment, even causing a fire. The operator has to keep one eye on the drying tables while loading, aligning and printing the table in front of her. Some skill in multitasking is required.

INKS

Most printing inks are soybean-based now, with petroleum-based inks having been phased out in the 1990's. Some shops are now using Plastisol inks, which have many advantages over soybean inks, but require a lot of heat to cure and have a consistency that is challenging to work with. I recently prepared some artwork for a screenprinting job that required me to supervise the production process. The screenprinter had over twenty years experience, and we were able to work through all of the little problems the job kept throwing at us, but he was in the midst of converting his operation to plastisol and was struggling a bit to get used to it. He claimed that it was less viscous than what he was used to, and required a different technique to work through the screen. Despite this, though, he said it was not runny, just more fluid under pressure.

EQUIPMENT AND PERSONNEL NEEDS

You'll need a means to create art (pen & ink on paper and/or a computer with vector graphics software and a large format printer). You can outsource your darkroom needs, or buy a camera and a lightbox. You can buy or fabricate screens. The carousel will probably be your biggest expense since you already have a place to work. Rags, solvents, emulsion, ink knives, a spraybooth, practice cloths... I'm sure I'm missing something.

As for production personnel, the primary roles you'll need to fill are artist and screenprinter. These are skilled positions. Screen cleaning, screen exposure, inventory control, film exposure, cleaning, etc. are menial tasks. One or two persons can run a small operation provided the workload is not too great and they are willing to devote the time to it (maybe lots of OT). This also does not address the need for office and sales staff.

LINKS

Here are some other places to look...

Equipment & Supplies

Equipment & Supplies

Inks

Plastisol Ink Facts

Screenprinting on Wikipedia

Sorry so wordy, just trying to help. Good luck!

[Chief.]

Thank you very much for taking the time to post that. I really appreciate it!

[bear69designs]

Thank you very much for taking the time to post that. I really appreciate it!

Glad too! I didn't mean to assume you didn't know jack about the subject, but it seemed like you were looking for any info you could get. I'm no expert, just wanted to help. I also hate to see "orphan threads." I think every sincere post deserves at least one reply, even if it is just to say "sorry, I can't help you, but good luck anyway."