Laser temp guns, test strips, and roasting neons!

[Du Manchu]

I need some clarity on the voodoo we call curing.  I think I tend to over-cure due to paranoia of a bad cure "out the door".  My comfort level is when my temp laser peaks at about 360-380 just as the shirt exits the 10' of tunnel on my old Hix dryer.  What stumps me, is when I double check temps with a test strip, those numbers are often much lower which makes me question which to trust, if any.  If I target a laser reading of 340, the strip may barely hit 290???.    To add to the confusion, as a final check the "pull test" is complicated when we can single stroke a color without a base, which creates a cure which "appears" to fail the "pull test" due to the thin deposit, but in actuality is fine (hopefully).

Regardless, all has turned out well with a setting of 365 and speed of a minute on dark shirts and 355 on lights, UNTIL I roasted a bunch of Neon yellow comfort colors tanks.  Literally roasted brown, due to an over-flash situation and a hot oven.   After about 15 settings test runs, I still don't trust the upcoming reprint cure.  My best cure thus far is oven setting of 350, only 3 of the 6 panels on,  & 1 minute in tunnel, which yields a fabric temp at the exit of about 340, ink of 310(laser), but the single stroked ink pull test cracks.  Anything more than this, and we are roasting brown.   One wash seemed okay, but I'm nervous.

As a follow up, I think once the moisture levels in the shirt reduce  after multiple oven trips, or over-flash, the shirt is more prone to burn.  I thought about misting the shirt prior to its trip through the oven, but that seems like a PIA and full of possible complications.

Any feedback on the laser and Neons would be greatly appreciated!

Thanks

[tonypep]

Donut probe is best for this. It tells you exactly what is going on in the dryer and can identify cold spots.

[blue moon]

great question!

this might not be the answer you are looking for, but ultimately the goal is to have the ink washfast.
For this job, you could run few scenarios and run them through few wash cycles. If they hold up, you know you are good. Doing it this way, you could print tomorrow rather than pull your hair out second guessing your decisions.

pierre

[Homer]

a bit off topic but we wash test all WB prints, but not as much as I like to on plastisol so I created a "supercharged badass wash machine testing facility" It's a Homer bucket from Home Depot, a cap full of simple green and a 1500 psi powerwasher....spray the piss out of the shirt until the bucket is full, check the results. temp guns only hit the surface, then reflect off the glossy prints and give false readings, test strips are meh, never gave me an accurate reading. A donut would be best I'm sure, but temps are such a variable thing, I believe the only real way to get accurate readings is to wash test and see for yourself.

patent pending on my machine so back off  ...

[nobrainsd]

Test strips have more thermal mass than most ink deposits. So they take longer to register the change of temp. You can see this in the way the strip darkens from the edges in. Temp strips are much better in a setting where they are testing for a target temp that is not changing rapidly. For example in an stable temp oven. It is not easy to use temp strips to accurately measure thin ink film temperatures. Thin ink deposits have a faster rate of change. Test strips drove me nuts. I no longer use them at all.

Maybe it was my skills, but donut probes need to maintain contact with the ink layer to measure properly and I found that difficult to do with light hand plastisol prints. They sure will map the cold spots if you have them.

The shirt and the ink layer heat up at different rates. Garments with more mass or lots of moisture absorbed will also have a varying rates of temp change. But the issue where your ink layer isn't heating up as much as you like before the shirt browns or scorches is an example of this disparity in the rate change. Lower the panel temps (or change the panel heights) and increase the dwell. That way the difference between the ink temp and the shirt temp will be less.  Higher panel temps and fast belt speeds will increase the differential. On light weight garments with relatively thick ink deposits I just have to slow down. For me, preheating my dryer so the shirts get some convection heat too helped me to even out my curing issues.

One nice thing about a donut would be to see if by only running a few panels you are ending up with cold zones that aren't doing much for you and then hitting it too hard on the remaining panels. I would not think to turn panels off as opposed to raising them or lowering the panels temp. But you know your dryer better than I do!

I'm fortunate to have a forced air dryer. I can run a higher garment temp ( 380- 390 off my infrared gun) and most garments won't scorch (except maybe those annoying flouro's which go off quick). So I can run fast and hot ensuring a cure. But in the end a slower and longer cure is the ticket to having the ink and shirt ramp up in speed more closely.

As Pierre states nothing means anything unless it wash tests.

[tonypep]

Since we post launder our Applique and recucle our rags we have two washers and dryers on site. Can wash test and get results right away. As stated above the two main factors here are retention time and temperature. Some dryers have gates on enter/exit that can improve efficiency. A few have raise lower options for the panels. Those are other variables to consider. I'll look around for a spare donut probe. Pretty sure we have one laying around. Lord we have so much stuff upstairs.

[ZooCity]

Wash test is the end all of cure tests- it's how the end user will see it!

I'm hoping to stub out for a washer/dryer in the shop for this purpose.  If you get a large enough capacity you could offer post-laundering with it as well as even small batch dyes and hey, free laundry machines if you don't have one in your home. 

We have an atkins probe and a higher end Raytek Raynger non-contact pyrometer, i.e., "laser gun". 

A laser gun reads the air space in a conical shape going out from the "barrel" of the gun.  You might see a laser dot but it's just the center of the end of that cone and, depending on your distance from the substrate, the readout is showing the avg temp within that conical shape.  So this is in no way the temp of your ink film, not even the surface temp of the ink film.  It is a nice, easy to use reference point if used consistently and at the proper distance from the substrate but always picture that cone when using it and check you have the distance ratio correct for the area you are trying to read.  Our gun has a little picture on the side to help with this if you forget.  Get the best one you can reasonably afford so you can assure yourself the readings are precise enough.

Donut probes, on the other hand, are showing "true" temps for the most part.  Yes, to get exact the wires must be inside the ink film.  You'll notice the probe will always read waaaay lower than the gun.  It makes sense when you think about it- the probe is reading the actual temp inside those crossed wires, not a cone of air above that area.  We're heating/steaming/cooking shirts here so that air above it at the back of the dryer is always going to be warm and add to a laser guns readout.  Not so with the probe, it's showing the real deal.  Second great thing about having a donut probe is you can hunt down hot/cool spots in your dryer which can make all the difference on finicky garments.

On most garments, I like our raygun to read from 360-380˚F at the back of the dryer.  On that same shirt, a donut probe will read no higher than 340-350˚F.    20-30˚F is probably about how much higher a gun reads on avg.

[Croft]

Buy a Atkins donut probe and drive yourself absolutly crazy because it will measure lower than a test strip,
   I have a brand new one so not a re-caliber issue here, if I ran shirts through so that the thermo probe  registered 320* my laser temp would read well in excess of 400*,
I take issue with printers on forums that swear by them but in the next post will spout off on tension on there Newman frames and 280+ meshes,   because the atkins thermoprobe says to place
thermo wire from the donut into the ink not on the surface , there is no way to immerse the wires on a print printed with anything higher than probably a double hit 110 mesh.
  All 3 are usable but all 3 shouldn't be trusted individually IMO.

For your problem with Neon they will be a high polyester count so they can't be run though the same as cotton. On our dryer we drop close to 100* and speed the belt up for them to work
and use our laser temp gun

[Du Manchu]

Yep....voodoo.

For wash test, are most folks washing them as a "worst case scenario" hot water, print outside, and hot dry cycle?  In how many wash cycles should you be able to determine if there is a problem cure?

Thanks.

[blue moon]

Yep....voodoo.

For wash test, are most folks washing them as a "worst case scenario" hot water, print outside, and hot dry cycle?  In how many wash cycles should you be able to determine if there is a problem cure?

Thanks.

for a quick test, I'll set the washer on a heavy soil, hot/col with prewash and second rinse. It is almost like going through three washes. Then tumble dry on high heat. If it survives that, my guess it will be OK.

pierre

[ZooCity]

People suck at washing cotton Ts which should be washed cold, inside out and not over dried.  Washing gently with hippie detergent and line drying is probably not the norm.

So I presume the worst and toss in some of that industrial strength costco detergent and wash warm on the heavy duty cycle.  One wash tells me if cure is complete.

For a wider perspective I'll run shirts over multiple washings as above.  Even take them home and throw 'em in with the dish towels just to see what they can take.  I only do that for new inks though.

One of the best is to keep and wear some and watch how they degrade over the years.

[mk162]

Also, when wash testing avoid the HE washers, most of them aren't hard enough on the clothes/prints.  The good ol' cheapie top loaders will beat the piss out of your clothes and really let you know you suck.

[brandon]

Donut probe is best for this. It tells you exactly what is going on in the dryer and can identify cold spots.

Our new one is arriving any day. Worth  e v e r y  penny.

And at our new space being worked on we are going to have a small washer/dryer combo just for this. Just run the garment over and over.....

Kind of like at the M&R facility where they have that print head just cycling over and over. I believe that is where I saw it!