Coating Question

[alan802]

I feel the same way about EOM as you when it comes to underbasing, or especially all white designs on dark garments.  I like to keep EOM ratios lower on spot color work and high on underbasing and white on dark.  You just don't need 25% EOM on a red print going on top of an underbase white, it's a total waste of emulsion and ink.

[Screened Gear]

I feel the same way about EOM as you when it comes to underbasing, or especially all white designs on dark garments.  I like to keep EOM ratios lower on spot color work and high on underbasing and white on dark.  You just don't need 25% EOM on a red print going on top of an underbase white, it's a total waste of emulsion and ink.

Could not agree more. I think that high EOM on top colors can be a major issue when printing wet on wet. That extra ink will get flattened out and expand then start mixing with touching colors after being smashed by a few screens. I still need some education on printing 5 to 6 colors wet on wet in a row. I am sure I will just get another flash before I get it down. I really don't have time for the frustrations.

[alan802]

I feel the same way about EOM as you when it comes to underbasing, or especially all white designs on dark garments.  I like to keep EOM ratios lower on spot color work and high on underbasing and white on dark.  You just don't need 25% EOM on a red print going on top of an underbase white, it's a total waste of emulsion and ink.

Could not agree more. I think that high EOM on top colors can be a major issue when printing wet on wet. That extra ink will get flattened out and expand then start mixing with touching colors after being smashed by a few screens. I still need some education on printing 5 to 6 colors wet on wet in a row. I am sure I will just get another flash before I get it down. I really don't have time for the frustrations.

I've been chasing that dream of 5-6 wow in a row for years, and for bold spot colors on top of an underbase...I don't want to say forget about it, but it's hard to do and sometimes you can do absolutely everything right and it won't work, but sometimes the moons and stars align and you're good.  Now sim process on darks and 8 color spot jobs wow on light garments, all day long.

[Screened Gear]

I guess I am just trying to do something I shouldn't be trying to do. It wouldn't be the first time. Now I know what to get the business for its 4th year in business. A new flash.

[alan802]

I guess I am just trying to do something I shouldn't be trying to do. It wouldn't be the first time. Now I know what to get the business for its 4th year in business. A new flash.

What size press do you have?  S-type right?  How many flashes do you have for it now?

[Screened Gear]

I have a 10 color E-type with one flash. I have the multiprint program so I can send it around again if needed. I will be getting a flash with the stand so I can move it around where needed. Right now my flash is in head 3 and has not moved. I haven't had that many issues with one flash but I know another one will make everything easier.

[Printficient]

Having read all the replies, I must say that the info given was a bit overwhelming.  The one thing that should be done to improve coating is flipping the screen instead of turning it.  This allows the emulsion to be applied in opposite directions and will help with the basic function of bridging the mesh with emulsion.  All the other stuff is nice but flipping helps answer the question.  Also on a side note you should always end up coating the ink side last.

[alan802]

I have a 10 color E-type with one flash. I have the multiprint program so I can send it around again if needed. I will be getting a flash with the stand so I can move it around where needed. Right now my flash is in head 3 and has not moved. I haven't had that many issues with one flash but I know another one will make everything easier.

Oh hell yeah, you need that second flash.  I can't wait to hear how much easier your life has become.  I thought that maybe you were talking about adding a third flash to a 12 or 14 color press.  I'd get that flash in there ASAP.  A second flash on an 8 color is a great addition, but on a 10 color, I'd say it's a "must-have" accessory.

[Gilligan]

The one thing that should be done to improve coating is flipping the screen instead of turning it.  This allows the emulsion to be applied in opposite directions and will help with the basic function of bridging the mesh with emulsion.

I kind of do this (but for a different reason)... I'd really need to see some microscope close ups of how this really makes a difference.  I just don't get it... in theory it sounds plausible, but in practice I'd think the physics just doesn't work out like that.  As long as you coat both sides I'd think that it will "ooze" around the fibers enough to "leech" into every nook and cranny.

If I'm wrong, then I'm wrong... just going of some practical thinking.

[ScreenPrinter123]

Gilligan and Printficient,

This was recently a discussion I had with someone at my office - about just flipping or turning the screen to the other side -- I kinda sided with Printficient because of a video I saw (maybe it's the one posted here recently on coating) -- but lately, we've just been going the path of least resistance, hoping Giligan is right and that it makes no difference.  Has anyone tried both methods with the same amount of coats and noticed any difference in printing opacity?

Secondly, is there a point at which I should just give up on trying to achieve halftones with coating many times?  I'm going to give a go on 7/7 tomorrow on a 150 s mesh (w/chromablue) because quite frankly I thought a 4/2 -- which someone recommended and which I tried today -- didn't end up creating all that great of a thick stencil - perhaps I'm pursuing a lost cause at trying to get a popping white on a first hit?  At any rate, a lot of the halftones shot out on the 4/2, but definitely not all.  So I am wondering if it gets to a point that the thicker you go with the EOM, the less likely the halftones will shoot out?  Assuming you have your exposure unit dialed in perfectly, I am wondering if the halftones would blow out by the time you were able to remove all the layers of emulsion on the stencil?  With the 4/2 the halftones didn't "melt" out like with the thinner EOM -- I had to work at them and then it was either stop and let some of them remain closed or start blowing out the ones that were already shot out correctly if I continued on shooting out the screen.  Anyone?  Beuller?

Thanks.

[Gilligan]

Though I agree with you, I also believe that our human hands/eyes aren't the way to determine if it is "just as good".

Maybe an auto coater could coat exactly the same... but our eyes on a print aren't a good enough judge to make a scientific conclusion.  Throwing this thing under some electron microscope or something that gives us more details deep down in there might give us a better scientific answer.

[inkman996]

Sounds,like you need some one to spend a little time,with you. Coating 7/7 times wow! And trying to retain halftones at that thickness yikes. Seriously you hear a ton about oem it does not mean everything needs to be a rubber gasket thick. Stepping up to higher mesh counts is just as important as all the other factors when achieving good half tones etc. developing a screen when exposed properly does not require all that much effort even for the smallest dots the screen ca handle, if you have to really work at it your over exposed and yep at that point you will blow out all the low percentage dots.

I have always been taught to flip a screen while coating but then I spent a couple years working with an auto coater that only rotated the screen as I was told just like gilligan said gravity etc does the job fine filling in the knuckles.

[mooseman]

you are really overthinking this.
the pressure you use should be enough to insure positive contact of the coater with the screen but should never be enough to distort or deflect the mesh from the pressure of the coater.
Oddly enough the amount of contact energy applied is directly related to the tension of the mesh.
you can push a bunch harder on a screen that is at 40Nm without deflecting the mesh. But use that same pressure on a screen that is at 25 Nm and you will deflect the mesh.
As I said before it is a touch , a feel, a learned mechanical process that if you have to actually think about you are over thinking it and most likely building in failure results from over complexing the process.

just for fun let me throw this at you....what about head pressure, no the the stuff you are thinking about but the amount of hydraulic pressure you get from the amount of liquid in the coater.

Just like diving into a pool the deeper you go the higher the pressure is on your body. likewise a full coater will offer more hydraulic load to the mesh than will a half full coater.
In terms of consistant coating and best EOM this is far more a factor than how hard you push the coater into the screen once you have made good contact.

test it for your self.  take a 1/2 inch length of PVC pipe and a 1 inch length of the same size  PVC pipe . Set the screen flat on a table shirt side up. Set  both pieces of PVC pipe  on the screen so they are standing upright and fill each to the top with your emulsion. See which one bleeds or pushes more emulsion through the screen sooner....head pressure baby, there is more weight in the taller pipe because there is more liquid column in the taller pipe thus more energy to push through the screen which is the whole idea when coating.
fill your coater 2/3 full at least keep a firm but reasonable contact pressure and stroke it till is shines, flip it and hit it again and you are good.
 

[JBLUE]

Gilligan and Printficient,

This was recently a discussion I had with someone at my office - about just flipping or turning the screen to the other side -- I kinda sided with Printficient because of a video I saw (maybe it's the one posted here recently on coating) -- but lately, we've just been going the path of least resistance, hoping Giligan is right and that it makes no difference.  Has anyone tried both methods with the same amount of coats and noticed any difference in printing opacity?

Secondly, is there a point at which I should just give up on trying to achieve halftones with coating many times?  I'm going to give a go on 7/7 tomorrow on a 150 s mesh (w/chromablue) because quite frankly I thought a 4/2 -- which someone recommended and which I tried today -- didn't end up creating all that great of a thick stencil - perhaps I'm pursuing a lost cause at trying to get a popping white on a first hit?  At any rate, a lot of the halftones shot out on the 4/2, but definitely not all.  So I am wondering if it gets to a point that the thicker you go with the EOM, the less likely the halftones will shoot out?  Assuming you have your exposure unit dialed in perfectly, I am wondering if the halftones would blow out by the time you were able to remove all the layers of emulsion on the stencil?  With the 4/2 the halftones didn't "melt" out like with the thinner EOM -- I had to work at them and then it was either stop and let some of them remain closed or start blowing out the ones that were already shot out correctly if I continued on shooting out the screen.  Anyone?  Beuller?

Thanks.

Take everything you said here and dont do it anymore. That will be the start of fixing your problems. You are doing way too many passes on those screens. Unless your trying to stop a bullet you do not need emulsion to be that thick.

What screen mesh are you using to try and get halftones to wash out?

[ScreenPrinter123]

Sounds,like you need some one to spend a little time,with you. Coating 7/7 times wow! And trying to retain halftones at that thickness yikes. Seriously you hear a ton about oem it does not mean everything needs to be a rubber gasket thick. Stepping up to higher mesh counts is just as important as all the other factors when achieving good half tones etc. developing a screen when exposed properly does not require all that much effort even for the smallest dots the screen ca handle, if you have to really work at it your over exposed and yep at that point you will blow out all the low percentage dots.

I have always been taught to flip a screen while coating but then I spent a couple years working with an auto coater that only rotated the screen as I was told just like gilligan said gravity etc does the job fine filling in the knuckles.

I'll try to post to let you know how the bullet stopping stencil comes out .