How thick is too thick?

[jvanick]

as part of the emulsion project, I just measured a few of my 156 mesh screens

I do 2 over 1 coating (1 coat on the shirt side followed by 2 coats squeegee side)

I measured the screen at 90microns
I then measured the emulsion in the middle at 135 microns.

that's giving me 45 microns of emulsion...  with the thicker side on the shirt side.

Seem correct?

[Shanarchy]

I use capillary film. Usually 50 micron. For high mesh counts 30 micron.

That's cap film, so it's only on the shirt side of the screen.

Not sure if that can help create a gauge for you. I'm sure some of the more technical guys will chime in.

[alan802]

That's a tad too thick in my opinion.

[Gilligan]

That's a tad too thick in my opinion.

Did Alan really just say that?

[mimosatexas]

lol

[Frog]

20% EOM is considered desirable for general printing, so a little under 20 microns would be the target I think.
That's general printing, not one hit whites and other special applications.

[alan802]

That's at roughly a 50% EOMR and you want to shoot for less than half of that with that mesh count, if I were coating.  On our 150/48's I like to see a 20 micron EOM and if it's 30 I'm not throwing things or if it's 10 I'm not all that upset either.  If it's a 156/64 and 50 microns EOM then you'll likely have "some" issues clearing the screen due to the tunnel length but if it's a 150/48 I doubt you'll have any problems other than using more emulsion than is really necessary for the best ink deposit.

[alan802]

That's a tad too thick in my opinion.

Did Alan really just say that?

I guess it's all relative.  And what your definition of thick is, which mine has changed a lot over the years.  When we first started doing one hit whites I was under the assumption I needed a thick stencil since we were achieving them with thick stencils but as things have evolved (brain matter as it pertains to screen printing increases) we've learned where stencil thickness matters and where it doesn't.  I'll just say our emulsion supplier was pretty happy for a while there.  It has changed a lot with the use of thinner thread mesh, that's the real game changer when it comes to this subject.

[jvanick]

I'll start to strive for less EOM then

Thanks!

*this is likely why my exposure times seem longer than other peoples.

[Shanarchy]

Alan, if I switch to smart mesh, would you say I should start using 30 micron film?

Ulano recommends the 50 micron for under 230 and the 30 for over 230.

Either way I am going to do some test runs with the 30 on lower mesh counts.

[alan802]

Alan, if I switch to smart mesh, would you say I should start using 30 micron film?

Ulano recommends the 50 micron for under 230 and the 30 for over 230.

Either way I am going to do some test runs with the 30 on lower mesh counts.

I would, but of course you need to see how the 30 holds up because the cap film is delicate and the 30 will likely need to be handled with a little more care during development.  The 30 micron will be more in line with the desired EOMR since, for example, the 150/48 will be about 30 microns thinner overall than a 156/64 so your EOM/EOMR will skyrocket if you go to the 150/48 and stick with the 50 micron film.

[Gilligan]

Alan, have you tried out a developing tank of just water yet?

My guy is LOVING ours... I think he'd rather scrub emulsion remover and have a developing tank vs a true dip tank.

[DannyGruninger]

I convert all of our EOM to % and here's where we are at 1/1 coating with our auto coating machine..... I'm not sure if it would apply to people coating by hand but with a 1/1 coating method on our auto coating machine here's roughly where we like to keep our eom


272-350 mesh = 5%-15% eom

standard thread = 20%

thin thread = 25-35%

I coat everything 1/1 in my shop and standard mesh counts get round edge of coater where thin thread gets sharp edge of the coater. On the same micron screens the difference between round vs sharp is 16% eom in my shop.....

I won't derail this thread but I've been testing emulsions lately with our eom guage on our auto coating machine and have had some crazy results.... Higher solids emulsions having less %eom, as well as sharp edge having more eom with some emulsions vs round edge, etc.... Lots of interesting things I've been noticing with eom so maybe we can get a discussion going again regarding that. Since we have the auto coater its been super awesome to play with that stuff.

[alan802]

That is very interesting Danny.  I would have never expected to see a 1/1 with the sharp edge and thin thread would get even close to 25% EOMR.  We haven't touched the sharp edge of our coater in years but I might just do it today and see what it is that could get you those results. 

But just so I get this right, you're getting 16% MORE EOMR using the round edge versus the sharp correct?  But in testing other emulsions you're seeing weird things like thicker stencils with the sharp versus round?

[alan802]

Alan, have you tried out a developing tank of just water yet?

My guy is LOVING ours... I think he'd rather scrub emulsion remover and have a developing tank vs a true dip tank.

Yeah, it's been a little over a year I think since we put the post exposure tank into production.  I love it, Carlos thinks it's a waste of time, so there is little doubt that it works great and speeds things up when you get things rolling.