Is discharge really less expensive?

[tonypep]

Normally that would be one stroke down the dryer for most discharge printers(double for high mesh). We keep about six unactivated reds on hand and usually one of them will be the right color for the job.

[Sbrem]

3 minutes in the dryer is forever. How about 2 runs through the dryers? Our is Gas and Infra-red...

Steve

[Rob Coleman]

Steve - If I can offer some guidance.....

Manufacturers must publish guidelines that they KNOW will work.  I spent 25 years at Wilflex, and I assure you that although every cure recommendation for a normal plastisol is 320f ... Many times it is lower.  The 320 gives a safety barrier if you will.  Also pigments and loadings are a factor in cure temp for plastisol so you need to state a temp to encompass all colors in a range.

But enough about plastisol!  Temperature, time, air flow, all play a role in curing discharge.  I would suggest you experiment with some consistent printing methods, controlled dryer settings, cure the discharge, document with a sharpie, and wash test several times.  For instance if the recommendation was 320 for 3 minutes -- maybe try 4-5 variations - say 330 for 1.5; 340 for 1; 320 for 3, etc.  This methodology can help to give you a base line.

But remember, if you do this on a day where the humidity level is 25 in your shop; wnd then run a job after the rain in the summer with the dock doors open and rh at 80% -- well those cotton shirts absorb a lot of moisture and your curing specifications can change.  You must drive out all the water from the ink film.

I would be interested to hear Tony and others thoughts on this.

Thanks and good luck!

[JBLUE]

Steve - If I can offer some guidance.....

Manufacturers must publish guidelines that they KNOW will work.  I spent 25 years at Wilflex, and I assure you that although every cure recommendation for a normal plastisol is 320f ... Many times it is lower.  The 320 gives a safety barrier if you will.  Also pigments and loadings are a factor in cure temp for plastisol so you need to state a temp to encompass all colors in a range.

But enough about plastisol!  Temperature, time, air flow, all play a role in curing discharge.  I would suggest you experiment with some consistent printing methods, controlled dryer settings, cure the discharge, document with a sharpie, and wash test several times.  For instance if the recommendation was 320 for 3 minutes -- maybe try 4-5 variations - say 330 for 1.5; 340 for 1; 320 for 3, etc.  This methodology can help to give you a base line.

But remember, if you do this on a day where the humidity level is 25 in your shop; wnd then run a job after the rain in the summer with the dock doors open and rh at 80% -- well those cotton shirts absorb a lot of moisture and your curing specifications can change.  You must drive out all the water from the ink film.

I would be interested to hear Tony and others thoughts on this.

Thanks and good luck!

How about 400 for 45 seconds?........

[Rob Coleman]

Or a microwave oven for 12 seconds!   

[dirkdiggler]

Sprint 2000, 12ft. heat, 375 degrees, speed at 13.  Take it to the bank!  It works!

[Admiral]

Sprint 2000, 12ft. heat, 375 degrees, speed at 13.  Take it to the bank!  It works!

fastest I've been willing to go is speed 11 with discharge / waterbase

not doubting that works though, used 355 speed 11 for a large non discharge job same dryer

[tonypep]

Good comments Rob. Remember the mfctrs recommendations on heat and retention times are usually based on 12' of heat chamber. Well, that doesn't apply to everyone. Some have 4, others 6 and some 20. . "Retention Time" is exponentionally shorter the longer the heat chamber is so this will differ widely. Also often overlooked is efficiency. Many, if not most dryers have gates located at the enter and exit positions. Lowering them to the sweeet spot helps to keep the heat in and speeds things up.

[Spreading Ink]

The other thing to keep in mind is how much ink you actually are laying down.  We run our all over discharge prints through an 86 inch wide interchange with 12' of heat (soon to be 25 foot of heat).  Some of these prints can have a lot of ink on them and large areas - the air flow of the interchange is a big help, but we do some jobs that run at 380-400 at 8 ft / min.  Others run fine at 12 - 13.  I can't wait to get the extension modules to be able to crank that belt speed up.  We aren't really doing this to increase our all over production as we currently use both sides of the 86 belt for them, but rather to support another press on this dryer.