wet on wet printing

[drew]

I was wondering, before I make a huge mess, if there are any tips or tricks I need to know before I attempt a wet on wet print. Is there anything I need to apply to the substrate side of the screen? I've heard as long as the art/colors don't overlap, its possible to print colors without flashing between prints. I'm just nervous about trying it because I don't see how the ink won't stick to the screen. This isn't a process job, just spot colors that don't overlap.

[ApeShirt]

You just may need to run several test prints in order to get good ink buildup on the screens before going to production.

[Dip.Schlitz]

Print smallest area of color to larger areas. Subsequent squeegee passes shouldn't run through the previous ink laid down. This could result in lines running through the print and uneven ink picking up on the backs of the next screens, which could then smear onto the next shirt. Consistency is key. Proper off-contacts along with a not too heavy-handed flood and stroke.

Jon has a video about using curable reducer to reduce tack for wet on wet printing, but in further research i have found that the ratio of reducer to ink is 3 drops (off a toothpick) to 8 oz. of ink. Which is incredibly miniscule. Usually curable reducer is used to "cut" the ink, but this usually causes ink to be runny and smear, even prone to washing out.

When flashing multi color prints i'll spray WD-40 or a silicone lubricant on a rag and wipe around the image on the back of the screen. This works to keep tacky, gelled ink from picking up on the screens. You don't want the screen to be wet, you're just creating a barrier between the emulsion and ink. If you can see a sheen, keep wiping. This may work for wet on wet, but i make no guarantees. When in doubt, flash.

[drew]

Thanks guys. I may play around on a day I don't have much going on but for now I think I'll just flash to be safe. Only takes 8-10 seconds anyway. Lol. I will try it this week, if I get time.

[Catspit Productions]

Yes 3 drop of reducer to 8 ounces of plastisol ink will likely do little but I am not sure where that info comes from. It’s actually advisable to contact the specific maker of your ink and reducer to find out their formula for mixing in reducer to reduce tack.

But the real key to printing wet on wet is the artwork. Instead of using butt/butt registration or overlapping colors anywhere you’ll need to leave a small line space between where colors meet. Maybe half a line point between where colors would otherwise touch when printed. This will allow for a space for the ink to bleed and meet. The bleed will increase as the ink build up on the back of the screens does.

Most often wet on wet works best with light garments and printing blacks last. If the last color ink printed looks too much different from the others due to pick up then run the last dark color on a higher mesh count to reduce the volume of ink printed.

By the way with flashed colors printed all you need to do is let the ink cool before printing the subsequent colors. Plastisol inks should not stick to other screens when semi cured and cooled enough.

[Dip.Schlitz]

Reducer claims come from Roger Jennings, in regard to Union Inks.
Ink picking up on screen could be a result of impatience, I suppose. Whether it be not enough time under the flash or not enough cooling time. Just trying to keep the machine moving because time is money. The WD-40 trick combats this issue.

[Catspit Productions]

Yes, each ink maker likely has different reducers and ratios so specifics are always good. I never tried using WD40 like that. I figured it would leave a smell. But if it works for you then that is what matters. Remember screen printing is such that what may work for one does not for another. The basic formula should be the same but I have seen many different variations on each part of the process that work but are not necessarily industry standards.

That’s a good point "under semi cured" ink is sticky and tacky even when cool. Normally I have found a rotary press with 4 to 6 stations gives me good cool down time between colors when loading the pallets and rotating while printing. But yeah you need to time the semi cure properly and that can be a pain in the rear, especially since it can take time for things to heat up which will then affect the dwell time. But once you get going you can rock

There used to be ink makers who made low tack inks too. But I can’t seem to locate any specifically for printing wet anymore. Also keep in mind a “high opacity” ink will not be a good ink to use for wet on wet even with a reducer.

[Dip.Schlitz]

Apologies for the sweeping generalization of curable reducers, as i'm sure not all are created equal. I almost exclusively use Union Inks and have found the need for reducer to be slim to none. Union offers "Ultrasoft" inks for wet-on-wet, light garments etc. I've too often seen reducer misused as an extender and the results can be problematic. Once bitten, twice shy we'll call it.
And I totally agree, "diff'rent strokes for diff'rent folks".

[Catspit Productions]

No apologies necessary. We’re all here to throw our 2 cents in. Yes! Union has a wide variety of ink lines. I have not used their inks in a long time. It used to be every ink maker had low tack inks but perhaps not anymore. Union is owned by Rutland and they are both owned by Rutland Technologies so maybe Rutland has some wet on wet inks too.

I have done so many black tees even here in AZ that I have a lot of HO inks and I wish I had a set of inks specifically for wet on wet. Sometimes it’s nice to be in a huge print shop with lots of different inks

Oh yeah, reducer is often used as a thinner and some suppliers recommend it as such. I recommend a soft hand base for thinning inks slightly. Some ink makers actually make a specific thinner for inks in my experience too.