Screen printing on dark fabric?

May 12, 2016 5:52 PM

I work with a small nonprofit that wants to screen print at least 50 (and up to 150) tote bags by Sunday (next Saturday in a pinch). Ideally we'd like to do (a) bright turquoise on black and (b) off-white on royal blue, but we're not sure if this is feasible. Any advice would be greatly appreciated.

We don't have access to professional screen printing equipment, so there's no quick, reliable curing method (e.g. a flash dryer). We might be able to find enough volunteers to iron, bake, and/or tumble-dry totes, but I don't know if these are workable solutions. I have a heatgun but have heard that this can be inconsistent and potentially lead to scorched fabric. Printing on an underbase is probably not an option.

Given this, is it possible to print nice, opaque colors on black and royal blue? Would it help if we did two coats, or chose different colors? Which inks would you recommend? Etc etc

Thanks very much in advance!

posted by junques to Grab Bag (8 answers total)

I screen print myself (and my band) t-shirts all the time, and as you can imagine, the shirts are mostly always black. For the ink, I just mix the desired color with a bunch of 'super opaque white' (that's the actual name of the ink color) and it shows up great on the black fabric.

For drying, I just toss them into the dryer inside-out for a bit (after they've already air-dried a bit). I guess this might be different for tote bags. If you can let them sit out and air dry for a bit, maybe even in the sun, that might be enough.
posted by destructive cactus at 6:09 PM on May 12, 2016 [2 favorites]

Off-white on royal will probably be ok. Anything on black will be tricky without an underbase, though. The thicker you can make the ink, the better it'll be.

Just wondering, if you could do two coats, why couldn't one of them be an underbase?

You'll probably be fine letting them air dry, if you have time. A dryer just speeds up the process.
posted by kevinbelt at 8:09 PM on May 12, 2016

i don't know what your budget is, but it looks like custom ink does tote bags (you have to call them) and offers three day rush. they might be able to do something for you.
posted by koroshiya at 8:22 PM on May 12, 2016

I don't know if it requires any special equipment, but the last time I had t-shirts printed with light graphics on a dark background, the shop used discharge ink. Their explanation was that it effectively removes the original dye from the fabric, giving the new ink a much lighter base.
posted by bradf at 9:23 PM on May 12, 2016

Home silkscreening on dark fabrics is tough -- you always need two coats. For the turquoise you need an opaque white base, and then you have to dry that and screen the turquoise on top, and line everything up exactly. The off-white can be screened twice as a color, or you can do a white base with off-white on top. How many screens do you have of your design? If you only have a single screen, it's going to take forever.

Also, if you aren't skilled at this already, you're going to have a lot of mistakes early on as everyone figures out how to do it right. There's a lot of details that go into good silkscreens -- amount of ink you use, how many passes you make with the squeegee, how hard to press down so you get paint all through the design but not so much it bleeds, how to line up the screen for a second pass with your top color, how long to dry them for and with what. . .

Speedball is the go-to ink everyone uses.

I really recommend looking into having this done by a local shop if you can. Tell them it's for a non-profit and they'll probably give you a discount.
posted by ananci at 11:03 PM on May 12, 2016 [1 favorite]

First, you will want to have the right screen. Mesh count is a measure of how many threads of mesh cross each other in a square inch. A 250 mesh count screen has 250 threads crossing per square inch. The more threads there are, the finer the holes in the screen, and the more resolution you'll have. Different mesh counts work better on different surfaces and with different images. A fiddly, complicated image with lots of little tiny detail requires a higher mesh count than a simple geometric shape. Lower mesh counts are better for textured surfaces, like a canvas tote bag. If your tote bags have a rougher texture, you will probably want a mesh count around 110. It's hard to give a precise number though, at least not without knowing the material you will be using. Don't forget that the lower mesh count will limit the detail you can have in your image.

Second, you will need to decide what kind of ink you will be using. Water based inks are easier to clean up, although they are not terribly opaque. As previous commenters suggested, you will probably need to either mix an opaque white in with your inks, do multiple drops of the same color, and/or print a white layer under your other colors. Registering (lining up) the white and color layers is fiddly and probably time consuming. Water based inks must be heat set. Speedball recommends using an iron on high for 3-5 minutes to set their inks. A heat gun may be used, but as you pointed out, they are not terribly accurate. I've scorched more than a few shirts using heat guns, but I've also made it work. A non-contact thermometer gun can help make sure you've got the right temp. You will need to get the ink up to around 300 F for a minute or two. I usually set Speedball acrylic inks at 320 F - 350 F for 2 minutes. I've heard of people using kitchen ovens to do this, but that seems like a bad idea.

Discharge inks (Ryonet video on Youtube) are a water based alternative, although it will be more expensive. Discharge inks require that you mix a discharge agent into your ink. The discharge agent will remove the dye from the fabric, allowing the lighter to color to pop on the dark fabric. Discharge inks only work on cotton, although I've seen interesting effects on cotton-poly blend fabrics. Discharge inks need to be used after mixing, as the discharge agent has a short shelf life. You will need a gram accurate scale for mixing the ink, to make sure that you've got the right ratio of ink to discharge agent. I've never worked with these inks, but I'm fairly sure they need to be heat set as well.

Plastisol inks are far more opaque than acrylic inks. Even light colors will pop on dark fabrics. However, these inks require rather nasty chemicals for clean up. Proper ventilation, a respirator, and good gloves and other protective gear are necessary. The longer I've worked with plastisol inks, the more paranoid I've gotten about safety. The other problem with plastisol inks is that they have to be heat set. They will remain wet indefinitely until they are set to somewhere around 320 F - 360 F. Plastisol never really dries, which is nice when you're printing someplace hot, or need to walk away from the press for a bit. Without a flash cure unit or conveyor dryer, it's a pain. I've used heat guns, with mixed results. The non contact thermometer makes it a lot easier, you just have to take your time and be patient. Plastisol will outgas during the heat setting process, so again, ventilation is important.
posted by cosimoilvecchio at 8:04 AM on May 13, 2016 [1 favorite]

If you have access to a cricut/silhouette cutting machine* you could use iron-on vinyl like this. I have used the white on a navy t-shirt and I thought it looked quite professional.

*or alot of VERY patient volunteers willing to cut carefully
posted by tinymegalo at 8:27 AM on May 13, 2016

Response by poster: Thanks for the answers everyone! Sorry this update is so dang late.

We ended up printing all 150 bags in one afternoon (we had five volunteers and one artist who had done some screenprinting before so that was gr8). There were a few mishaps but nothing too major.

Short version: super opaque white ink seemed to do the trick--it helped that we were already going for off-white and a light-ish sort of green.

Longer version: We used Jacquard Versatex inks--mostly the Super Opaque White--along with their Color Fixer. I wish we'd gone a bit darker on the off-white 'cause it mostly looks white to me. When wet the green was initially closer to aqua than turquoise (which would've been fine really) but it ended up drying a bit darker (hooray).

The colors showed up well in one medium-thick coat; opacity didn't seem to be an issue. Our prints weren't as solid/clean/dark/etc as pro-quality stuff (a bit distressed, vintage perhaps) but quite good under the circumstances. You can take a look here--pictures aren't that great but I can take better ones if anyone's interested.

The Color Fixer was supposed to eliminate the need for heat-curing so we just air-dried everything for a few days. I'm still not sure if the print can withstand machine-washing though... once again if anyone's curious I can pick up a bag or three and run some tests.

All in all a worthwhile endeavor.
posted by junques at 11:06 PM on October 25, 2016