screen printing > Newbie

Discharge ink ->more ink or more heat?

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OhNoPrinting:
yeah, wanna give discharge ink a second try..

the first set of shirts gave me mixed results. Mainly because i didn´t stir the ink well enough (i guess: i used the same ink a couple hours later and it got much better) and by using scrap shirts.

Now if i want it to discharge more.. (less vintage look) would i use: more of the activator (recommended on pot: 5-10%), try to get more ink onto the shirt or set the dryer temp higher?

*using a pfp didn´t give me better results

Frog:
Remind us of what dryer you use. Forced air is a real need with waterbased inks, discharge of not.

tonypep:
Pics would help pls

OhNoPrinting:
oh, i love to include photos :-)

Dryer is a Workhorse Powerhouse (most likely 2608) Quartz Dryer: (no forced air)



here a B&C E190 (100% cotton/185 g/m²) shirt going into the dryer:



Early attempt after dryer (on 180 degree C / inside dryer around one minute 20 secs):



Let the ink soak overnight and try again:



the red shirt (from H&M) came out really nice:



but a day later, had some discoloration appear:



So, how do I always get really clean (less vintage) prints: I probably need to stir the ink better, but.. is there another trick? heat? activator? (i am cheap so i guess i used 5% instead of 10%)? Using a lighter shirt?

ps: my favorite shirt out of that session is by the way a poloshirt -> that really looked cool with discharge

blue moon:
6% activator is standard. With red ink try 3%.
regular temperature as the plastisol, but much, much longer times. You have to actually dry the ink (unlike plastisol which has a chemical reaction and is almost instant once the temperature is reached) so all the water evaporates. This could be several minutes in the dryer.

few thoughts:
-once activated ink has a limited shelf life and will generally not discharge as well later on. In some cases you can add more powder and reactivate. You'll have to do your own testing to find out.
-shirts should go through the dryer in one pass. might have to run the belt at lowest speed possible.
-shirts have to be discharge compatible. For the most part that would be 100% cotton. Some blends work, but not many. Shirts have to be dyed with a reactive dye. You can mix some powder with water and dab the shirt on the inside of the seam. You'll be able to tell how well it works without ruining the shirt.
-some colors work better than others. look for a discharge compatibility/performance chart from Gildan and Anvil. In general purple and royal don't work. Reds tend to be tough. Your best bet is to look at the charts and then order few shirts and do the testing. Once you find stuff that works stick with it.
-even the shirts that work will have issues. There might be more dye in one lot than other. They could be made in different countries and so on. Your size Large might print different than Medium. This will not happen often, but it will. and you most likely just ruined some shirts.
-re-dyes don't work. Manufacturers might make a ton of Kelley green for st patrick's day and if they don't sell they are stuck with them. They will dye them black in order to move them, but re-dyes don't discharge well. So a safe color like black might not work. Make sure you specify when ordering that you shirts are for discharge. This should prevent getting re-dyes.

We have several ppl here that are very good with discharge and they could help more. My observations are few years old, but I would imagine they still are valid.

pj 

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