More Exposure testing and Dot Testing

[jsheridan]

All right.. lets get this train back on track shall we.

The Densitometer has arrived!!

doing my first test films tonight.

[jsheridan]

With the Densitometer I was able to calibrate the RIP's dot curve and create some new test films.

Started to burn the films tonight and on the 2nd test screen.. I was able to wash out some 3% dots on my 205 mesh 

I'm going to re-coat 1x1 and adjust exposure then post the results. 

[bimmridder]

I want a densitometer! What did you get? Ball park pricing?

[jsheridan]

It was loaned to me from a friend 

You can find a basic transmission meter to read your dots on fleabay or nationwide craigslist search engines for around $250-350

A reflective and transmission meter jumps to about $650-900 used.

[ZooCity]

Totally jealous.  I use the 'eyeball' technique to enter my linearization values into Accurip.  I look at the film and guess how much each 10% increment of fill is actually printing as.  Then, I try and do the same on-press.  It gets it close but not close enough that you're optimizing your ability to resolve the %s at the ends.  I'd love to be pulling off 3% dots consistently and knowing exactly when it's going to happen rather than them being bonus dots. 

The densitometer is the easiest approach but, I wonder, could you put your films and then your test printed garments under a microscope, grid off an area, measure the ink within it, do a little math and get the values that way?  Or is that way more work in the end?

I would really like a way to close the loop, so to speak, and get a calibration happening on what is going to show up on press after gain.  This would expedite and empower the separation process so much.  Instead, I feel like I'm just going with my gut all the time.

[blue moon]

Totally jealous.  I use the 'eyeball' technique to enter my linearization values into Accurip.  I look at the film and guess how much each 10% increment of fill is actually printing as.  Then, I try and do the same on-press.  It gets it close but not close enough that you're optimizing your ability to resolve the %s at the ends.  I'd love to be pulling off 3% dots consistently and knowing exactly when it's going to happen rather than them being bonus dots. 

The densitometer is the easiest approach but, I wonder, could you put your films and then your test printed garments under a microscope, grid off an area, measure the ink within it, do a little math and get the values that way?  Or is that way more work in the end?

I would really like a way to close the loop, so to speak, and get a calibration happening on what is going to show up on press after gain.  This would expedite and empower the separation process so much.  Instead, I feel like I'm just going with my gut all the time.

I don't think you can calibrate the print on the garment. I tried taking some readings, but it is just about impossible to get  consistent results. Also, every time you print WOW you'll squish (that is the official term BTW!) the previous dots and create more dot gain! The amount of dot gain is going to change when you adjust the pressure on the previous screens, the off contact, the mesh, the garment and so on. I can see being able to calibrate the 4CP as the screens can be set up the same way every time (your black screen can always be third and get "stepped on" by the following hard black and white highlight). You would have to test on a specific garment and hope that the next time you get it it comes from the same mill.

TBC . . .

pierre

[jsheridan]

The only time I measure dots on a shirt is for dot gain and  5 prints will result in 5 readings. The best you can do is take 10 readings, then average them and do this for each and every brand of shirt you use. Keep that chart by the artists and let them know beforehand what kind of shirt the print is going on. You will find that a 55 line screen works awesome on an AA shirt but looks muted on a Gildan 2000 where you'll need to use a 51 line to get the same dot coverage.

One of the shops i worked in.. we spent about 2 months testing our 4CP seps to account for the squish on each plate. The Y plate had as much as 50% dot gain by the time the final screen would step on it while the K plate had none as it was the last ink color down. When the testing was all done, our 4CP prints were amazing and always on tone. It helped that we did some crazy color bar testing along with dot testing that the art dept would use as a reference when building 4CP designs.

[Dottonedan]

I used to love doing all that. I am not such a huge fan of going that far into the testing. Reason being, is that each  job still plays a role in the out come. Some you need to speed up or slow down the pass or angle it  straight or out further or, or. So once you got your dot gain deciphering all worked out, you still have that varying variables. So I feel you can only go so far and then the finer efforts just get lost/covered up in the mix.


Just curious, how did the Co. you worked for adjust or handle the different calibration of dot gain with each different plate of the CMYK?  Did they output them individually and have a specific dot gain adjustment based on sequence?


Thanks
Dan

[Gilligan]

Just curious, how did the Co. you worked for adjust or handle the different calibration of dot gain with each different plate of the CMYK?  Did they output them individually and have a specific dot gain adjustment based on sequence?

Not that I'm even close but I was curious about this too.

[jsheridan]

We used PS to assign gain then output the channels. It was a tedius process each time we did 4CP but the results were heavenly.

Did I mention that I got that 3% dot with my flourescent light unit..using high output unfiltered UV bulbs 

[Dottonedan]

Did I mention that I got that 3% dot with my flourescent light unit..using high output unfiltered UV bulbs 

WOW!  That IS note worthy. GREAT!  Feels good to accomplish the not so common. What line screen was it again?


D

[Homer]

i'm looking to linearize my printer and accurip, this thread is a super good read for those interested. and here is a little more about it. . .anyone have any other testing results or find somebody with a densitometer?

http://murakamiscreen.com/wp-content/uploads/2012/07/Linearization.pdf

[JBLUE]

Your suppliers of print supplies should have one. One thing to note is every film brand has different amounts of dot gain. So when you linearize your printer you will want to stay using the same film or you will need to re-linearize to be accurate.

[Dottonedan]

JBLUE.




Good point.  These are the little things that effect the outcome in subtle ways that if we are not careful can compounded with other similar small ways, and leave you wondering what happened.


I was reminded by Winston last week when he came in for a visit of the fact that my dryer (being very old) that heating elements that emit the heat are tubes that run length wise through the dryer.  So, As the shirt runs through the chamber, it's only got so much surface area that is constantly getting the same amount of heat.  I knew this was an issue from somewhere, but it never dawned on me.


Sad day for me but he said he can rotate the housing and re mount it so they run across from side to side.


Poor design in the early days but they didn't know what we know today...back then. The wiring was a bad design in it as well.