We are printing 5 colors on a full white underbase on different colors of dark shirts. The shirts look pretty good, but we normally don't deal with this many colors on white, so i have a few questions.
1. Shirt Fibers with White Base
I am finding that small dots in the white base are hard to fill in with the last colors that we are printing (not perfectly smooth base). We are using Union Ink Bright Cotton White on a 110 with Print flash Print underbase. We are flashing after every color as the entire print has a white base. I did find that misting a little water on the shirt and wiping it back before printing really helps smooth the shirt for a nice base. I find that shirts like Beefy-T's are worse to deal with because they seem to have a lot of fibers. This problem is not due to the ink sticking to the screen, it is coming off nice and clean, it really is the fibers in the shirt. Do other people mist the shirt with water? Are there any other tricks to printing colors over white and have it nice and smooth (no ridges that are hard to cover with the color) ? Keep in mind that by the time the last dark colors go down, the white on the shirt has been flashed many times.
2. Shiny Parts of The Color Print
If the color print on the white base is not just right, it seems to leave some areas of the color more shiny than others. What is the cause of this? For example, a large red color area printed over a large white area. If things are not perfect, it seems to leave blotches of the area more shiny than others. Could this be caused by the white ink being too hot on the shirt in places or something? It seems to happen more if the screen doesnt pop right off the shirt back to off-contact. If it kind of slowly sticks to the print, that part would be shiny. Maybe this has to do with #3 below?
3. Platen Temps
Since we have to flash after every color, the platens seem to get extremely hot by the end of the shirt run. We run 4 station 6 color. If you flash each time for 10 seconds, the board is so hot the tack adhesive starts to break down. We even run a fan on the station after flash and then an open station. When you pull the shirt off after done, the tack is more of an oil substance and no longer sticky until it cools off. I am wondering if this breakdown and heat is causing the shiny problems in some areas in #2 above? Do we need to stop and allow much more time for cooling the ink/board after each flash? This is really a problem as we can't get a good production run going.
Again, the prints do look pretty good, but i am a perfectionist i guess and would like to know any tricks to fix the above issues. We just cant seem to get a good production run going to knock the shirts out faster without these little issues popping up. Its just one or more of the above things seem to continuously slow us down!
all your problems sound like you're just way too hot. that's a good idea w/ the fan.
can you get by without hitting the white twice? that's one less trip under the flash. it does not have to be a 100% bright white to get good colors on top. i've noticed i get better underbases on something like a 156 on the base to get a smoother print. if there is white in the design, try a 1 print underbase and then the highlight white last. and remember, once it's flashed, if there's any roughness in the print, it's locked in. get it as smooth as possible before you flash. you may have to swing the flash to the side or step your palettes away from it to keep from burning stuff, but the first print HAS to be smooth.
10 seconds might be too long, too, you just want to gel the underbase, not cure it. Pace your self to where you have about 6-7 sec under the flash and make sure the print is somewhat cool by the time it gets back to you.
Thanks for the information. Well, we have to have a base because there is also plenty of white in the image. If you add the 5 colors, we are basically up against it and can't have a screen for highlight white.
I really think the first white is smooth, I have good off-contact and i am flood-print-flash twice.
At this point i might have to slow things down and not use a station for the flash, maybe flash next to the station i am at and then have all other 3 stations to cool before the next print.
What about using the water mist? Does anyone else do that for smoother white? Seems to be working for me. Also, what about a spray adhesive that can hold up to more flashing during a run? Any recommendations?
i just re-read that, your press is full that's why you hit the white 2x, my bad.
i've done the water once and it does work, it just slows me down. then you need to evaporate the water, so that's just more time under the flash.
you might just need more tack after every 4 shirts. i think it's just too hot. i recently switched to waterbase, roll-on adhesive and i love it. the tack lasts longer and a fine mist of water will reactivate it some what as long as it's not totally covered in shirt fuzz.
Yep, i am definitely going to try to cool things down a bit. I am also going to get tack made more made for flashing so it doesnt break down.
One other thing i realized is that i only did 1/1 on my base plate screen. I think i should also put more stencil on it to get a better maybe smoother base. Maybe coat it 2-3 times on the back. That might help me with the problem in #1 above where its kind of hard to cover the white without getting little pin size white showing through because of the roughness of the fibers in the shirt. I never have this problem on Gildan shirts but i have had this problem with Beefy-T's and the Anvil. They just seem to have more fibers that are hard to smooth out.
are you pulling the white? maybe try pushing. if you're careful, you shouldn't get ink coming through the shirt, but you will get more pressure to smooth things out... without killing your arms!! i push my whites 95% of the time.
Definitely try the waterbased adhesive.. I use it on my platen when I have to do a multiple color job. IT seems that the hotter the adhesive gets the better it works..
for single color jobs I still use the Spray adhesive, but for any job requiring a flash I use the Waterbased roll-on adhesive.
i'm sure most suppliers carry it, but you can definitely get it from ryonet (silkscreeningsupplies.com)
-Scott Lewis
p.s. I have never tried to spray the shirts with water before pressing.
p.s. Also I would always double or triple coat a screen you will be using for white. I find that when I don't double coat a screen for white I have much more difficulty with the screen when pressing. It's harder to get all the white out of the screen and it takes more strokes/prints to get a solid white. When I use a double coated screen for white it takes much less effort and force to get a clean white.
5 color plus base white job questions 
