Testing of Screenprinting Ink and Lines Per Inch - 11.05.23
The other problem was that I was using inks that were not compatible with the CMYK screen printing process, which means that any colour that was on top of the ink applied would be the more prominent colour that would be on the print.
To combat this, I had to buy screen printing ink that was specifically for the CMYK process and is water based for dry fasting and for use with halftones, not for general screen printing. I also think that the best thing to do for the project is to use an A0 screens to print the posters onto as this would provide a nice sized poster. The only problem that I have is that the ink costs me an arm and a leg at the moment, so I cannot mess anything up at this stage, even experimenting with the screens could cost me more money.
But... the inks work. The second photo shown in the slideshow shows how layering helps with the final outcome.
I first used the normal technique of using Cyan first and follow the CMYK printing order again, but these outcomes would translate to colours not being correct. I felt like I was lost with this project and that these experiments have not worked at all and I would not have a final project. I also thought that I was late for work and was rushing things to get done (even though I did not have work due to them not needing me that day)
I had nothing to lose (other than inks and time) and I had looked at CMYK screen printing processes and how to screen print photos onto garments online (whilst I was sick with food poisoning) and they recommend that I put the yellow on first and add colours starting from the lightest to the darkest. This was the only thing that I had not done from the beginning of the screen printing process. This was because I thought that this process was only used for ink that can be absorbed by the white garment and only useful for garments as well.
And thus, it worked... The colours shown in the print are the same colours that my colour calibrated screen shows and I now have a reference as to how many Lines Per Inch (or LPI ) I would need for the final project.
I also had to be careful of not properly drying from cleaning and letting the ink dry too quickly on the screens with the paper still underneath the screens, which caused the paper at 5 LPI to stick onto the screen and rip the paper. Not letting the screen dry after cleaning also resulted in ink bleeding through the paper as this would have too much water and would then cause the pigment in the ink to bleed through the screen and into the paper. I might experiment with this ink bleed effect later in another future project. But for now, this is an unintentional effect that I do not want in the final posters.
One of the tutors here in college also recommended using a high GSM paper due to inks overlapping and saturating the paper with ink. It also says on the web page of the inks that I would need to have at least 120 GSM to not have the paper buckle and warp in the screen printing process.