Coating Question

[ScreenPrinter123]

When you are coating your print side first (at least I do -- and then the ink side/squeegee side last) do you try to have the coater's edge barely touching the print side to increase your stencil?  I've always done that, as I've found that to create a thicker stencil, but sometimes I'm trying to have the coater touch the screen so little that it sags and drips.  Is that the correct method or should I be pressing harder against the mesh on the print side on my first coat(s)?

Thanks.

[inkman996]

No you need to have firm pressure on the coaters edge at all times both sides. Your not trying to create the actually thickness like taping drywall. Every time you make a pass with the coater it leaves a certain amount of emulsion then when you finish up on the ink side all the emulsion is pushed to the shirt side creating the thickness.

[Parker 1]

No you need to have firm pressure on the coaters edge at all times both sides. Your not trying to create the actually thickness like taping drywall. Every time you make a pass with the coater it leaves a certain amount of emulsion then when you finish up on the ink side all the emulsion is pushed to the shirt side creating the thickness.

Agreed...
Also dry the screens with the print/shirt side facing down.

[ScreenPrinter123]

So you'd say apply more or basically the same pressure when doing your last coat on the ink side (applying more is the method I've done, but that is of course assuming that I was applying very little pressure on the print side)?


Thanks.

[alan802]

I will agree with Mike in that you need more pressure.  It may take more strokes to get your stencil but you'll have more consistency and better stencils overall if you use the same amount of pressure and keep everything as uniform as possible.  Just gliding the scoop coater over the mesh leaves too many things that could affect the thickness of the emulsion deposit.  Viscosity and solids content, along with temperature and flow characteristics of the emulsion will start affecting stencil thickness instead of number of coating strokes, speed and pressure.  You're just inviting a few more variables into the equation in my opinion by doing it that way.

I'd not add or decrease pressure on the first or last and just keep everything the same throughout so when you do get to where you can start measuring you'll have more consistency and that is key to stencil thickness once you have the thickness you want.

[blue moon]

I will agree with Mike in that you need more pressure.  It may take more strokes to get your stencil but you'll have more consistency and better stencils overall if you use the same amount of pressure and keep everything as uniform as possible.  Just gliding the scoop coater over the mesh leaves too many things that could affect the thickness of the emulsion deposit.  Viscosity and solids content, along with temperature and flow characteristics of the emulsion will start affecting stencil thickness instead of number of coating strokes, speed and pressure.  You're just inviting a few more variables into the equation in my opinion by doing it that way.

I'd not add or decrease pressure on the first or last and just keep everything the same throughout so when you do get to where you can start measuring you'll have more consistency and that is key to stencil thickness once you have the thickness you want.

push until you break one screen  and than back up. If the mesh is not creaking and making noises, you are not pushing hard enough!

OK, that might be a little too much, but really, only a little too much. You should be pushing hard! As Alan said, it will give you consistency with the emulsion thickness on the screen which in turn will give you consistency (predictability and repeatability) on the press!

pierre


pierre

[Denis Kolar]

Check somewhere around 11th minute

How to coat a screen with emulsion - Screen Printing

[Screened Gear]

Your guys are all nuts. Pushing hard enough to break the screen? Firm pressure is fine. If your screens are flat and your mesh is tight then all you need to do is put enough pressure so that the blade of the coater is tight against the mesh. I coat 10 to 20 screens at a time and if I was pushing as hard as your guys are saying I would be worn out after doing them. I coat fast 2/1 with the sharp side. I get a nice 12 to 20 EOM depending on mesh count (give or take 3% to 4%). Stencil thickness is important. I know there are tons of ways to do everything but pushing as hard as some of you is way over kill. Consistent firm pressure with consistent speed is key. Also check your screens. I hold a screen up a light to check thickness and smoothness of the coat. If you hold the screen up to the UV safe light you will be able to gauge the thickness of your emulsion depending on mesh count and color of mesh. I have been doing this for a while and can tell when I am too light on the emulsion or too thick.  Its not a perfect way of doing it but it does give you a small level of quality control before the screens are dry. If you see the screen has light and dark areas just redo your coating on that screen. Then check it again.

[inkman996]

I am going to go out on a limb and assume Pierre was exaggerating how hard to push. And yes firm pressure is important, as Pierre stated enough to hear a little creaking is good.

[Screened Gear]

I am going to go out on a limb and assume Pierre was exaggerating how hard to push. And yes firm pressure is important, as Pierre stated enough to hear a little creaking is good.

I know Pierre was joking but what if someone else reading this didn't know. I will say you can not push too hard on the coater. It takes practice to control the coater. I think a beginner should understand its all about consistency. If your just trying to push really hard you will not be able to control your speed. Its just like printing white ink. You have to find the right balance of pressure and speed to lay down a smooth consistent layer. Once you get it down its easy.

[inkman996]

I find that pushing with firm pressure takes away the chance of inconsistent thickness if you tried to be to soft.

[Croft]

Firm pressure and a constant speed and angle , I find coaters will speed up on the top half of screen and also start to roll the coater up too soon , you can see that the emulion will be thinner in that area.  But basically practice makes perfect, 20-25 -  23"31" screens will make you tired.

I've always used a 5gal. pail as my support for a screen , which can be a little sore on the back but works for me ( not too tall). Floor, Waist or table height coating has never felt comfortable for me.

[alan802]

Your guys are all nuts. Pushing hard enough to break the screen? Firm pressure is fine. If your screens are flat and your mesh is tight then all you need to do is put enough pressure so that the blade of the coater is tight against the mesh. I coat 10 to 20 screens at a time and if I was pushing as hard as your guys are saying I would be worn out after doing them. I coat fast 2/1 with the sharp side. I get a nice 12 to 20 EOM depending on mesh count (give or take 3% to 4%). Stencil thickness is important. I know there are tons of ways to do everything but pushing as hard as some of you is way over kill. Consistent firm pressure with consistent speed is key. Also check your screens. I hold a screen up a light to check thickness and smoothness of the coat. If you hold the screen up to the UV safe light you will be able to gauge the thickness of your emulsion depending on mesh count and color of mesh. I have been doing this for a while and can tell when I am too light on the emulsion or too thick.  Its not a perfect way of doing it but it does give you a small level of quality control before the screens are dry. If you see the screen has light and dark areas just redo your coating on that screen. Then check it again.

I wish I could measure the actual pressure I'm applying to the mesh when coating but I'll just have to guess at it being around 6-8lbs and I don't hear any crackling or popping noises of the mesh, just the sound of metal gliding across mesh at around 10"/sec.

Are you getting 12-20 "%" EOM or 12-20 "microns" EOM with the sharp edge?  I've compared both edges a lot over the years and will continue to do so every once in a while but the rounded edge has always worked better for us, especially when getting into the thicker stencil needs.  I'm shooting for 20% EOM for 156-205 and 12-15% for 225-330, 30% all the way up to 50%+ for some of our 83-140's.  I can build a thick stencil with the sharp edge but it takes a bit more work so we have always used the rounded edge for every mesh count and every stencil thickness we were trying to achieve.  I am going to go out and try to coat a screen with the Saati PHW Red and the sharp edge of the coater on some low mesh counts and I'll report back here as soon as I can.  Is there any reason why you like the sharp edge versus the round?

[Screened Gear]

Your guys are all nuts. Pushing hard enough to break the screen? Firm pressure is fine. If your screens are flat and your mesh is tight then all you need to do is put enough pressure so that the blade of the coater is tight against the mesh. I coat 10 to 20 screens at a time and if I was pushing as hard as your guys are saying I would be worn out after doing them. I coat fast 2/1 with the sharp side. I get a nice 12 to 20 EOM depending on mesh count (give or take 3% to 4%). Stencil thickness is important. I know there are tons of ways to do everything but pushing as hard as some of you is way over kill. Consistent firm pressure with consistent speed is key. Also check your screens. I hold a screen up a light to check thickness and smoothness of the coat. If you hold the screen up to the UV safe light you will be able to gauge the thickness of your emulsion depending on mesh count and color of mesh. I have been doing this for a while and can tell when I am too light on the emulsion or too thick.  Its not a perfect way of doing it but it does give you a small level of quality control before the screens are dry. If you see the screen has light and dark areas just redo your coating on that screen. Then check it again.

I wish I could measure the actual pressure I'm applying to the mesh when coating but I'll just have to guess at it being around 6-8lbs and I don't hear any crackling or popping noises of the mesh, just the sound of metal gliding across mesh at around 10"/sec.

Are you getting 12-20 "%" EOM or 12-20 "microns" EOM with the sharp edge?  I've compared both edges a lot over the years and will continue to do so every once in a while but the rounded edge has always worked better for us, especially when getting into the thicker stencil needs.  I'm shooting for 20% EOM for 156-205 and 12-15% for 225-330, 30% all the way up to 50%+ for some of our 83-140's.  I can build a thick stencil with the sharp edge but it takes a bit more work so we have always used the rounded edge for every mesh count and every stencil thickness we were trying to achieve.  I am going to go out and try to coat a screen with the Saati PHW Red and the sharp edge of the coater on some low mesh counts and I'll report back here as soon as I can.  Is there any reason why you like the sharp edge versus the round?

Alan,

I am not sure if it is that I keep the emulsion in the refrigerator (cold thicker body) or if I am doing something else different that is giving me my results. I get 12 to 20 percent of EOM when coating with Aquasol HV sharp side 2/1 on my 123 - 230 mesh. I haven't measured them in a while. I can't use the round side. I get way to much emulsion lay down. I do use firm pressure. I know what Pierre is talking about cracking or mesh noise. Most of the time its the screens that are not glued as well as others. I am going to measure a few of the screens that I have in the shop and see what they are at. I would hate to mislead anyone. I don't try to get really high EOM. I think for white inks EOM is great but for top colors or printing on light colored shirts you can get great results with very low EOM. I will get back to this in a few hours.

[Screened Gear]

OK I just checked a few screens that I have right now.

1 - 86 was at 28% (I never use this screen)
3 - 123 they were 13- 16% EOM
6 - 155 they at 11-12% EOM (surprised all 6 were that close)
2 - 230 they were 8-11%
1 - 305 it was at 7%

When I was measuring them a while back I was always between 3 and 5 percent on the same mesh.

They are a little lower but still fine for what I need them for. I know when I coated these I was in a hurry so I am sure that played into it. I have been swamped and have been rushing everything lately. I guess I need to measure them a little more.