Over the last few months I have invested in a 2 colour screen printing setup. I purchased exposure lamps, blank screens 43t, waterbased ink etc etc.
Tonight I finally had all the bits and pieces and set about exposing my first design, and pulling my first screened tshirt.
The Design
I laid the design out in Illustrator and printed out on A4 transparency film. I actually printed x2 of the same design because I was worried the black ink wasnt thick enough to block all the light. I made sure the design had fine registration marks and went about sticking the two sheets together to create a much more solid black. This worked a treat.
The Screen Emulsion
I mixed up the entire pot of emulsion as it's pretty cheap and does store for a few weeks. I left to sit for about 2 hours before coating the screen. I covered the screen with 3 even coats. I then left the screen to dry in a dark room leant up against a radiator. I flipped the screen every 20mins to ensure an even dry. The emulsion dried perfectly.
The Exposure
The exposure unit I purchased had no set information on how long to expose screens for so I decided on 25mins (this was a total guess). I placed the glass over the film/screen/foam and left alone. When the 25mins was up I dismantled the setup and took the screen over to the sink. I ran warm water across the screen and gently rubbed with a soft cloth. The design started to appear straight away and after about 5mins of work I had the screen finished, dry and ready to use. This was a HUGE (but nice) surprise because this was the part of the process I was worried about the most.
The Print
I placed a tshirt on the machine using hi-tak spray to hold it in place. I spooned out a long blob of ink across the screen and pulled the squeegie across approx 3 times.
The Result! - And where I need advice...
Well, it's not awful... but it aint good either. The main problem is the edges are blurred. This is confusing because the exposed screen edges are very sharp. I looks as if the ink has 'bled' on the tshirt material causing this effect. I also observed it had bled through the tee and I could see the design in reverse on the inside. I used the ink direct from the container, and it was of a pretty thick consistency so I was pretty surprised/disappointed to see this. The white ink on black tshirt was also not as bold as I hoped. It seemed to be a very light grey. It seemed like the coat of ink wasn't thick enough.
I grabbed my nearest Threadless t-shirt and compared. This was pretty depressing. The Threadless print was far more detailed and the ink appeared to be far thicker (almost creating a very small 3D effect). When I compared mine I realised how far I was from the result I require.
I would be forever in your debt if you could address some of my points and suggest where I could improve/change my technique. I eagerly await any replies
I spooned out a long blob of ink across the screen and pulled the squeegie across approx 3 times.
Three pulls is a lot. Sometimes you need three, but 1 or 2 will often get the job done.
Quote:
Originally Posted by plasticated
The main problem is the edges are blurred. This is confusing because the exposed screen edges are very sharp.
The first thing I thought when I read the first sentence was that maybe the screen hadn't exposed correctly, but if the screen is sharp then it might be that it's moving in between printing. Even clamped into a press the screen can move (or if the mesh is loose the mesh can move). It's also possible to drive ink under the screen if the squeegee angle is too acute.
Quote:
Originally Posted by plasticated
I looks as if the ink has 'bled' on the tshirt material causing this effect. I also observed it had bled through the tee and I could see the design in reverse on the inside.
Sounds like you're laying down too much ink. I'd start with cutting down the squeegee pulls and see if that helps.
Quote:
Originally Posted by plasticated
The white ink on black tshirt was also not as bold as I hoped. It seemed to be a very light grey. It seemed like the coat of ink wasn't thick enough.
I'm assuming you're using waterbased ink and not plastisol.
There are a couple of possibilities here: 1) It needs two coats of ink (print, flash dry, print), so just one layer is going to look faint, or 2) Some opaque inks I've seen change colour/opacity when cured. They look faint until that point, then everything changes.
Quote:
Originally Posted by plasticated
I grabbed my nearest Threadless t-shirt and compared. This was pretty depressing. The Threadless print was far more detailed and the ink appeared to be far thicker (almost creating a very small 3D effect). When I compared mine I realised how far I was from the result I require.
Threadless shirts are printed with plastisol (for the most part anyway) so if you're using waterbased ink as I surmise they're not going to look exactly the same. Waterbased doesn't really have a 3D effect; a lot of people consider that a benefit, but for some it's a drawback.
It's strange, I woke up this morning and almost immediately I was struck with the thought that I hadn't heat sealed the design in any way. The company I purchased the ink from suggest using a heat gun, similar to that used to strip wallpaper. That could be the important step I was missing as I just left the design to air dry. It's just possible that this missing step would improve the opacity of the ink. I also agree, I pulled the screen too many times, which probably caused some bleed. Now I am looking at the print in proper daylight (I finished my printing session at about 5am!) I noticed an amount of 'stepping' on the curves of the design. Is this because the screen mesh is too wide. Should I have a finer mesh? Im using 43t now.
I really am looking for the kind of result I have seen on the Threadless tees I have in my own personal collection. I do like that slightly raised effect. By the sounds of it, that would mean investing in Plastisol inks and a flash curer. I have come this far so I suppose a bit more money spent to get the result I want wont hurt. My only concern about Plastisol is the clean up process after each screening session. How do you go about cleaning a screen covered in ink that isn't waterbased? I assume washing it it with water will have no effect?
Last edited by plasticated; January 20th, 2007 at 08:20 AM.
My only concern about Plastisol is the clean up process after each screening session. How do you go about cleaning a screen covered in ink that isn't waterbased? I assume washing it it with water will have no effect?
Its not that big a deal....just scrape off the excess ink...Then you can use a screen wash in a spray bottle and paper towels to clean the screen...
Its not the monster people make it out to be...
Ive done a little more research into Plastisol and it seems that is the way to go.
I tried another screen today, but I spent much longer setting up the machine and adjusting the settings. As a result the screen much closer to the tee when lowered, which created a more accurate print with less bleed. However,I noticed that the screen still had some residue of white ink in the fine mesh which caused the print to me patchy. Looking at the Plastisol ink it seems because the ink itself doesn't ever dry without heat, it would be easier to clean using a solvent spray and ensure no residue in the mesh.
I feel that even just doing these two small tests I have learned so much more than I ever did reading websites and books. Hopefully a few weeks down the line, when I have the new Plastisol ink and flash dryer I may finally be able to produce a product I would be happy to sell. I am very excited
plasticated, where did you get your kit from? I did my first print the other day in 43T and I had the same problem, although only from one pull of the squeegee. I'm going to try the 90T screen that I was supplied with the kit.
Just wondering whether you were advised to rub the screen to get the emulsion off? I'd have thought that could damage the image..... perhaps some of the experienced members could advise here? ta
I bought the equipment from ebay, although all from different people.
I rubbed very gently with a soft cloth, so there wasn't a lot of abrasion. The stepping effect if definitely an artefact of the screen itself, rather than my process. In fact I have to say that out of the whole process I am most proud of how the screen turned out.
I think moving to Plastisol is going to improve my output. After further reading it seems waterbased inks are not good at creating a totally opaque print without multiple passes (pull, heat gun dry, pull again). As most of my designs will be on dark garments I think this is the best plan of action.
I am going to scour this forum for more info on 43t vs 90t. As a graphic design by trade I can only assume a finer mesh will create a more accurate image, much like an increased DPI of an image will increase its resolution. A rudimentary google tells me:
43t is #110 per inch where as 90t is #230 per inch.
As a graphic design by trade I can only assume a finer mesh will create a more accurate image, much like an increased DPI of an image will increase its resolution.
Yes. It will also give you less ink deposit (sometimes a desired effect, sometimes not - not when you need to get a lot of white down onto black fabric for example), dry out faster (if you're using waterbased inks), or be harder to push the ink through the mesh (if you're using plastisol). That's not to say don't do it, but there's reasons behind everything and it's pretty much always a series of tradeoffs.
Quote:
Originally Posted by plasticated
A rudimentary google tells me:
43t is #110 per inch where as 90t is #230 per inch.
I guessed that might be the case. Out of interest, would you say printing white on black garments is a bad idea using 90t? I am realising that getting a proper coverage, even with Plastisol will require 2 passes anyway.
Do you think 2 passes (pull, flash dry, pull again) would create a solid print?
My reference point here is the Threadless tees which I would single out as the best example of accurate screen printing on dark garments. Does anyone know their process?
Out of interest, would you say printing white on black garments is a bad idea using 90t?
To be honest I'm just not experienced enough with mesh counts to say. 43t suits my purposes most of the time, so I rarely stray from it for fabric (and if I do I'm more likely to go to 77t than 90t). I'm still learning the ropes, and being more adventurous with mesh counts is one of those things I need to learn.
(a few printers here will be able to give you a straight up answer if they see your post though)
Quote:
Originally Posted by plasticated
My reference point here is the Threadless tees which I would single out as the best example of accurate screen printing on dark garments. Does anyone know their process?
Threadless aren't at all unique in their print quality, but for the most part it is very good (I noticed the last shirt I got from them was slightly off-registered, but generally they're good and even this shirt is still fine to wear).
As for their process... screenprinting with plastisol using an automatic carousel. Sometimes they use other types of screenprinting (foil, discharge, I imagine some waterbased), but the bulk of their printing would be standard plastisol printing - no tricks or special techniques, just done by an experienced volume printer.
My first ever screenprint - A post mortem 
