Fades & Half Tones

wooh..nice say josh..you realy are very good in printing shirt..perfect angle..i realy appreciate yourpoint..i kept studying the perfect angle of the tones..but when you said go to angle 20'..CMYK process..will it work?? pls reply for me ..thanx a lot josh

 

hey ncgraphicboy..

your right, its fun playing eith tones..diferrent angle size of tones you wish too..but i have just one question..what do you prfer the best anlge for CMYK print..pls help me.thanx a lot for your time..

clinton

Graphic designer

Hi Clinton,

I rarely ever use that type of halftone for 4 color process work, or CMYK printing. In CMYK layouts, you can specify transparency, or lighten/darken an image as necessary, without concerning yourself with halftones. If you specify a color at 50%, then it will output exactly as input. Same thing applies to transparency. CMYK designs are usually renedered at 300dpi or higher, so haftone images are just not needed. You can easily create a duotone (still at 300 dpi), consisting of just 2 colors, in the bitmap dialog box. If you still wish to use a halftone in your CMYK design, just play with it until it looks right on your monitor. For 300dpi output, you need a 150 line screen, 400dpi would require a 200 line screen, and so on. Hope this helps!

Ciao,

PommyJosh:

I know the guys I am trying to do this for has some large professional epson printer...but he is totally computer illiterate.

 

are they printing the screen positive onto clear film via the Epson using the straight non-PS driver?

One thing to remember when using heavy halftones in screenprinting is to take the percentage that is showing on the screen and knock it down about 10 percentage points (if possible), I've found that this helps mitigate the dot gain and give you a print thats closer to what youget one the screen.

 

I've never had a need to go down as far as 35lpi, minimum of 45 usually, with most things going out at 55lpi (both for manual and automatic presses). The most important thing is to change all of your angles to 22.5, this will help avoid any moire problems.

Doug Swearingen:

One thing to remember when using heavy halftones in screenprinting is to take the percentage that is showing on the screen and knock it down about 10 percentage points (if possible), I've found that this helps mitigate the dot gain and give you a print thats closer to what youget one the screen.

 

I've never had a need to go down as far as 35lpi, minimum of 45 usually, with most things going out at 55lpi (both for manual and automatic presses). The most important thing is to change all of your angles to 22.5, this will help avoid any moire problems.

A design like this, white on a black shirt a 35lpi dot will burn on a #110 very easily.  The dots will be easier to burn as well as hold on press (shirt). Dot gain should be very minimal. The print will also be fine up close as well as at a distance.  Higher mesh frames are a little trickier yet will result in a softer look and feel. I stay in the 45-65 range at my shop, yet still go down for certain designs without compromising the quality or look. Mainly cartoon type designs and logos.

Also keeps production rolling.

<ncgraphicboy> wrote in message news:39034@coreldraw.com...

Actually, it is not that difficult to emulate the halftone to view on your computer monitor. You must first convert the vector portion in question to a bitmap, then go to menu Bitmap > Color Transform > Halftone...

PommyJosh:

Hi Guys

 I recently started working with a screen printer, re-drawing the scraps of paper his customers give him into nice clean vector art. But I am struggling with my half tones.

 What is the best was to create a half tone for screen printing?

 This is the image, it will be a one colour (white) print on a black t-shirt. I just need to get my half tones correct or it will look like crap!

 Any help would be greatly appreciated!

 

Be aware that the image you see on a monitor or paper will not be what it looks like when screen printed. Solid colors are fine but shades of color will gain in density when screen printed. An object that you fill with 80% of a color will look more like a solid fill when printed. This is dot gain and the amount of 'gain' will depend on several factors such as squeegee hardness, sharpness, and pressure and mesh count and tightness. On the other end of the tone range, depending on the quality of the positive, the emulsion, and the exposure setup, you may not be able to capture something as small of a 10% dot when using normal line frequencies. I design using tones between 20% and 80%. Being a manual printer, I can, if need be, increase the density of the tones to achieve the look I want during on press printing. - Scotty 

Hmmm, very informative post Scotty.

scottyjr:

PommyJosh:

Hi Guys

 I recently started working with a screen printer, re-drawing the scraps of paper his customers give him into nice clean vector art. But I am struggling with my half tones.

 What is the best was to create a half tone for screen printing?

 This is the image, it will be a one colour (white) print on a black t-shirt. I just need to get my half tones correct or it will look like crap!

 Any help would be greatly appreciated!

 

Be aware that the image you see on a monitor or paper will not be what it looks like when screen printed. Solid colors are fine but shades of color will gain in density when screen printed. An object that you fill with 80% of a color will look more like a solid fill when printed. This is dot gain and the amount of 'gain' will depend on several factors such as squeegee hardness, sharpness, and pressure and mesh count and tightness. On the other end of the tone range, depending on the quality of the positive, the emulsion, and the exposure setup, you may not be able to capture something as small of a 10% dot when using normal line frequencies. I design using tones between 20% and 80%. Being a manual printer, I can, if need be, increase the density of the tones to achieve the look I want during on press printing. - Scotty 

Scotty, this isn't entirely true. You can indeed produce halftones in screenprinting, either by using the Postscript printer driver as suggested in this thread, or by manually converting the image to a halftone first (also demonstrated in this thread).  You can basically turn any vector image into halftones, by using the Bitmap > Mode > B/W dialog, choose the shape, angle, and lpi, and you have a halftone image.  You can then CorelTrace the image to turn it back into vector art, if desired.  It will print out exactly as it appears on your monitor, even with a non-postscript printer.  This method is not as desirable in most cases for actual screenprinting as using the RIP postscript options, but I did this for many years before I had a PS printer, and still use the technique today to create that graphic  'comic book' screen feeling.

 

Hi NC, The "Bitmap>Color Transform>Halftone" doesn't give the right kind of dots for screen printing, Screen Printers like Pure Monochormic dots which are generated by PS and Black & White dialog in corel as you've suggested.

Aleem Ashraf:

Hi NC, The "Bitmap>Color Transform>Halftone" doesn't give the right kind of dots for screen printing, Screen Printers like Pure Monochormic dots which are generated by PS and Black & White dialog in corel as you've suggested.

Hi Aleem, With all due respect, I have to disagree with you on this one. It totally depends on the type of look you are going for. I didn't want to see all the detail in the original cassette, rather I wanted to create the obvious dot pattern that you see on your monitor.  The dots created using this method, in pure monochrome ( Bitmap>Mode>B/W>Line Art), will actually burn on most types of screens with no problems.  You won't need to do anything special with your postscript device other than output.  No RIP, no angles or line frequencies to worry about, just print the b/w image right to paper or film. In fact, you don't even need a PS printer at all!  You can use a plain old ink jet to make your film.  It's pure black & white now, so everything you see on the screen and in the design will print to film and burn to the screen just as it is.  This addresses fountain (gradient) fills, and shades of gray (or other colors) which screenprinters are rarely able to achieve with decent results.

Will you still see those dots on the finished product? Absolutely! That's the whole point behind my last demo.  It's about the graphic quality of the dots, and being able to see the dot pattern clearly.  This style is quite popular here in the U.S. , and is especially useful when creating more vintage designs. I use the same technique to create dot patterns for traditional printing, or even for web graphics. It may produce a unique effect from what you're used to doing in your business, but trust me, it does work for screenprinting, and gives the artist control over the dot size and look, rather than leaving it in the hands of the screenprinter.  Their vision is rarely ever the same as the artists!  I could even take it a step further and trace it back into b/w vector art! That's what screenprinters really want... Black & White vectors.  If you like, I'll send you a camera ready PDF vector file for you to burn and try it out. You will be amazed at how cool and graphic it looks when you see the image appear just as it is in the example.

I realize there are many other ways to create dot patterns for halftones, as I have previously written about. But not that will produce these same results. It is just one way to create the dot pattern yourself, which you can see on your monitor, a unique look that a screenprinter probably would not make with a PS device.

 

Is there a way to create different types of "fades/halftones" in ie; Concentric Circles, Parallel Lines, Parallel Wavy Lines, Thin Irregular Lines, Grains Patterns Resembling old steel engravings, Wood Grains, Mezzotint Screen, Linen Texture Screen, Three-Tone Posterization, etc squares or really large halftones for a design effect?  Iv'e seen "Subway" employee t-shirt where they have this effect.  It looks like POP art.  The "Halftone" effect that iv'e tried in the past is always choppy.  Is there a way to create these effects with vector clairity?  (Or close enough for screenprinting.)

 

Thanks, 
Matt

 

wrote in message news:87743@coreldraw.com...
> Is there a way to create different types of "fades/halftones" in ie;
> Concentric Circles, Parallel Lines, Parallel Wavy Lines, Thin Irregular
> Lines, Grains PatternsResembling old steel engravings, Wood Grains,
> Mezzotint Screen, Linen Texture Screen, Three-Tone Posterization, etc
> squares or really large halftones for a design effect? Iv'e seen "Subway"
> employee t-shirt where they have this effect. It looks like POP art. The
> "Halftone" effect that iv'e tried in the past is always choppy. Is there
> a way to create these effects with vector clairity? (Or close enough for
> screenprinting.)
>

you're printing to a postcript printer, correct?

If so, in your Print dialog box, go to the Separations tab - make sure Print
Separations is checked, then click on the Advanced button in the Options
there. At the bottom of the Advanced Seps dialog, there is a dropdown for
Halftone Type - it will give you many options there.

Also, on the Postscript tab, at the bottom is a Screen Frequency dropdown to
change your LPI (or the size of the halftone "dots"...

Does this help?

Matt, as you say, the best way that I've found is to indeed use vector dots.

To avoid doing them semi-automatically, Rasterbator provides a wonderful alternative.