How much do you choke your underbase on auto press?

[bryanprints]

We've been running a Sabre for a few months.  Had an old freedom before that.  Running static frames that we rotate in and out to try to keep good tension.

I feel like anytime we go under 3 pixels for choke we run into issues of the under base sneaking out here and there. 

What is everyone at?  How do you handle a run of shirts that has a small part of the under base showing on a few?  Name of the game?  We always make the adjustment, but the damage has been done on those few.

[Doug S]

The max here is 1 pt.  Most of the time it is a 1/2 and sometimes a 1/4.  It just depends on how fine the print is needing the ub.  We use shurlocs mainly and roller frames for any process work. 

[Doug S]

When I say 1 pt max I mean that's the most I've ever choked which is really a 1/2 point because the stroke is overlapping the underbase.  As far as tension, do you have a meter to check?  Also, make sure your squeegee pressure is roughly the same across all screens especially if they are in register and the ub is peaking out from the bottom of the print only.

[3Deep]

Choking should be done in the art department way before the screens are burn, plus knowing how tight of registration your press will hold gives the art department a glue of how to output the film.  Simply way to check how tight your reggie is on your press take one screen and print it twice, you can check each head doing this, I've been able to print an underbase with a 1 pt stroke and with higher mesh tight screens a 1/2 pt stroke...nice tight screens will tell you very quick how well your film was output and if you might have a problem with your film printers output also.

[blue moon]

you should consider trapping instead of choking. . . It distorts the image less when combined with less opaque inks.

Also, the points will work as measurement in Illustrator or vector based programs (0.5 point). When talking points with rasters it will depend on the resolution of the image. At 300dpi, it usually a point for us. 

pierre

[Stinkhorn Press]

.75 pt (so half that) normally.

BUT.
is you press true, paralleled?
are you screens tight enough, and evenly tight?
do you attempt to print with as low a pressure you can get away with?

[mimosatexas]

3 pixels at 300ppi? is that centered or aligned to the inside?

I print everything at 600ppi and center my stroke on my UB, usually using 6px, but ALSO I trap my top colors (usually also by 6px).  This works out to about 1% difference in the size of the top vs the base.  This varies a lot based on the art though as fine details may or may not let you choke or trap effectively.

For reference, 1 point = 1/72 of an inch.  If you are centering the stroke on your base, your choke is effectively half a point, which is equal to .7% difference between top and base.

[StinkyDaddy]

I'm at 1 pt with newmans and a BWM/Hopkins manual.
It's taken me years to get there, used to be as much as 5 pt back in the 90's.

[Inkworks]

.5 point here, sometimes less if it's tricky, sometimes more if i'm feeling generous and it will look goo on the finished product. Large traps can look bad on some projects.

[ZooCity]

Would one of you trappers explain to me how you are getting along with this on textiles?  We only trap on flatstock or where the substrate might shift/warp.   I'd love to incorporate it to ease setups but can't see trapping top colors working on textiles very well, I'm sure I'm missing something.

We choke ub up to 0.5pt (aligned to inside) or 2px @ 350ppi.

[Colin]

Chris, its always artwork dependent.

Fine text I will try to add a stroke to the top color since trapping my base plate could make the text dissapear.  Sometimes I need to split the trap and the choke, so a 1/2 goes on the top color and half to the base plate.

For bulky designs it's choking the base.   For fine designs, I have to play it by ear..... sometimes you cant really do anything other than tell the customer we will try our best!

300 dpi we choke 1 pixel if the base is going through 225s mesh.  If we are going through a lower mesh count like 150s  I will up the resolution to 600 dpi and go 3 pixels.  3 pixels @ 600 = 1.5 pixels @ 300.  Sometimes...... I will go 5 pixels if trying to do a double underbase...

Vector we will go either .5pt or .75pt for all chokes.

[mimosatexas]

Top colors on a dark shirt basically disappear into the shirt, so only what is underbase is visible. Bases are usually on lower meshes, and I frequently run double bases. Both of those lead to gain and top colors on higher mesh gain less, so the the actual choke and trap ends up being closer than it is on the film's. Like colin said, a ton of it is artwork dependent and you just kind of get used to what works and what doesnt. I will say it is basically impossible for me to print pixel on pixel without choking and trapping a bit.

[1964GN]

I choke 2px at 300dpi when using raster/photoshop. I only do spot color stuff in Illustrator if there is no underbase. I am just more comfortable and 100 times faster with Photoshop but my Illustrator skills are improving.

White on white I never choke the underbase

I almost never trap. I always trapped when doing higher end 4cp heat transfer seps but for garments I have never found the need for it.

[Biverson]

I use simple seps and am at 2px for 300dpi and 4px for 600dpi (what I use most). I wish there was an option for 3 though.


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[Colin]

Does simpleseps automate that process for you?