I find that everytime I go to print fine half tones, the screens after shooting seem to have theses "checkered pattern, or someone used the term morray (?) How can you avoid this ? Is it something to do with the angles of the art.....HELP !
It could be a combination of a few factors. The basics:
Take your screen mesh and divide it by 4 or 5. I usually do 4.5 and it works well. So if you are printing on a 305 mesh, you could easily have a halftone of around 70. The angle should be 45, but 22.5 seems to work better along with an elliptical dot.
If you are trying to print on something like a 155 mesh, then you probably wouldn't want to go over 35 lpi. So it varies, but once you play with these numbers, your moire patterns will disappear.
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If you hold the positive up against your screen you might see some interference fringes which come & go as you rotate the positive. This is a moiré.
It's caused by interference between two sets of repeating objects that have differing frequencies. That can be your halftones and the mesh threads or the knuckles where mesh threads cross. 45 & 90 degrees are really bad angles for moiré because meshes have threads and knuckles at those angles.
You will find that the mesh tension has a great effect on where moiré occurs, so a positive will moiré on one mesh and not another.
Thanks a bunch! This may be an old post but came in handy today. It never dawned on me to place the film on a screen without emulsion and turn it to see the morais.
If any one knows how to change the screen angle of the cyan film in AccuRip please post. I have changed the angle to 22.5 and and selected "apply" but the angle contiues to print at the 15 degree default.
Yes, this is called "Moirrée" in French.
When your half-tone is not placed well according to your mesh-angle; you will have moirrée.
Whe make our films with a 22,5° angle and at 45 lpi.
It's moire with an / accent on the e (which doesn't seem to cut & paste on the forum), pronounced mworray, preferably in a french accent. You can turn off the halftoning in Accurip and use the angles from your DTP programme, AI or Corel for example.
hello sirs i just read this post i just have a question for a 200 and a 230 mesh what lpi would you recommend? tnx alot. i am just gonna be starting out and i am trying to learn everything i can. tnx alot. also sir for a 305 mesh would a 55 lpi be appropriate? tnx again.
hello sirs i just read this post i just have a question for a 200 and a 230 mesh what lpi would you recommend? tnx alot. i am just gonna be starting out and i am trying to learn everything i can. tnx alot. also sir for a 305 mesh would a 55 lpi be appropriate? tnx again.
200=40-45lpi
230=45-50lpi
305=60-65lpi
I've read some general recommendations of 3-5 meaning divide mesh count by a figure between 3-5 to get the correct lpi. I seem to notice that a figure of 4-5.5 is better or maybe easier. Using 5.5 should lower the above lpis by 5.
Multiply your prefered LPI by 4.5, and you will get around the mesh count you should use. If you need more opacity then multiply by 4. The idea here is a hole in you stencil (DOT), should be represented by at least 4 openings in your mesh. Thread diameters also matter, if your mesh doesn't give you it's thread diameter or percentage of opening then those threads could be larger then need to be, which cuts down on the amount of ink that can pass through the openings. There is typically 3 standard thread diameters avaliable per mesh count. And each thread diameter will give you a different percentage of opening. Pick the thread diameter that is in the middle. The thinnest thread diameters have the most percentage of open area, but usually can't hold up the the abuse people put on them, especially when you are stretching them up above 20 newtons. The thickest thread diameters make it more difficult to print, because the percentage of open area is less then the other two diameters.
Use angles of 22.5, and or 56. Never use the default angles that photoshop or any graphics program offer. These angles are for offset litho printing, They don't have mesh to deal with.
__________________ "If it's not the same...Then it's different".
Multiply your prefered LPI by 4.5, and you will get around the mesh count you should use. If you need more opacity then multiply by 4. The idea here is a hole in you stencil (DOT), should be represented by at least 4 openings in your mesh. Thread diameters also matter, if your mesh doesn't give you it's thread diameter or percentage of opening then those threads could be larger then need to be, which cuts down on the amount of ink that can pass through the openings. There is typically 3 standard thread diameters avaliable per mesh count. And each thread diameter will give you a different percentage of opening. Pick the thread diameter that is in the middle. The thinnest thread diameters have the most percentage of open area, but usually can't hold up the the abuse people put on them, especially when you are stretching them up above 20 newtons. The thickest thread diameters make it more difficult to print, because the percentage of open area is less then the other two diameters.
Use angles of 22.5, and or 56. Never use the default angles that photoshop or any graphics program offer. These angles are for offset litho printing, They don't have mesh to deal with.
__________________ "If it's not the same...Then it's different".
ok tnx alot sirs. now i have an idea on what lpi to use. also for some basic spot colors would you recommend 230mesh or should i drop down to a lower mesh count? btw i am going to be using plastisol. because i read in some threads that if you go for a lower mesh sometimes the print will be shiny because of to much ink.
It really depends on your market and your image. Many Filipinos seem to prefer a solid and shiny color which is why I have 180-200 mesh and am slow to move to 230-350 mesh. But if your market is a little picky, they may want the "thinner" feel of plastisol that comes with 230 mesh screens. I think you have to try it for yourself and see how customers react. I would advise starting with lower mesh count (156, 180 or 200max) then move to a higher mesh if you think you need to. It will make your life easier and you are unlikely to outgrow your need for lower mesh count so the screens won't go to waste.
Multiply your prefered LPI by 4.5, and you will get around the mesh count you should use. If you need more opacity then multiply by 4. The idea here is a hole in you stencil (DOT), should be represented by at least 4 openings in your mesh. Thread diameters also matter, if your mesh doesn't give you it's thread diameter or percentage of opening then those threads could be larger then need to be, which cuts down on the amount of ink that can pass through the openings. There is typically 3 standard thread diameters avaliable per mesh count. And each thread diameter will give you a different percentage of opening. Pick the thread diameter that is in the middle. The thinnest thread diameters have the most percentage of open area, but usually can't hold up the the abuse people put on them, especially when you are stretching them up above 20 newtons. The thickest thread diameters make it more difficult to print, because the percentage of open area is less then the other two diameters.
Use angles of 22.5, and or 56. Never use the default angles that photoshop or any graphics program offer. These angles are for offset litho printing, They don't have mesh to deal with.
Thanks, this is exactly the kind of answer I was looking for. So what your saying is that you get the number 4.5 from the idea that each halftone dot in your image should fit within at least 4 to 5 openings in the mesh? Is this correct?
Printing half tones screen issues 
also sir for a 305 mesh would a 55 lpi be appropriate? tnx again.
