EOM measurements and emulsion testing done today

[blue moon]

we had a Chromaline rep here today and tested a bunch of stuff.
here are few tidbits:

our 305's are coated at 20% EOM
110's were at close to 50%!!!!

and we are resolving 3% dot at 55lpi on regular 305 mesh (at 20% EOM!!!) even though it is crazy thick. There is mesh interference and you can see the individual threads blocking the openings, but the emulsion is actually creating a dot above it (no ink can get through, but the emulsion is resolving.

So we are hitting the limits of the mesh with our current procedures and are not going to gain better resolution by switching to another emulsion. We tried several diazo and photo-polymer types and it did not really matter much how many coats we had. Anything between 1+1 and 1+3 was resolving about the same.

lessons learned:
-get an EOM meter! I though we were at 10-15% on thinner threads and around 20-25% on 110-160, but so much for guessing!
-we are going to start coating 1+1 rather than 1+2 which we currently do. We will probably leave the 110's at 1+2 as the thicker stencil needed for the white spot deposits might suffer too much by going thinner.

I'll add more as I think of it, gotta go catch up with some work after spending the whole morning messing with this!

pierre

p.s. oh, and after we were done testing, I found that we have a leak in the vacuum blanket and were not even getting the best results we could. . .

[blue moon]

obviously, good films and good exposure unit contribute to the small dot being held even with thick stencil. We are using the AccuInk and have seen the Dmax increase about 75% when we started using it. We did also switch from a 3000 to a 4800, but the RIP and the films are the same.

pierre

[alan802]

Our 305's are 10-15%, 110's are closer to 50%, much like yours.  25% on 156, 20% on 175-195, and 15% on 230's.  Those numbers are what we shoot for, obviously there is some variation.

Most of the reps that do all this definitely don't recommend going over 20-25% on any EOM, at least the ones that have been in here.  I know when I tell them our EOM on 110, 123 and 140's they just about flip out, but I've printed many many jobs with 15-25% EOM on those lower counts and the ink deposit simply isn't thick enough for decent (or to my liking) coverage.  I think you'll find that if you start going down to the recommended 20% or so on those low mesh screens, you'll save ink but you'll probably not like those white prints on darks, and you sure won't be able to do any "one hit" prints on darks or mediums.

[ZooCity]

Awesome Pierre.  I'm jealous of your new found knowledge.  It's so empowering to finally know and have numbers to compare. 

I agree with Alan.  Maximum EOM that still lets you resolve the detail you expect from the mesh typically.  You are simply providing yourself with more ink to shear. 

On my mesh chart I have exposure values for two coating methods for every mesh.  So, we can coat a 150/48 2/2 or 2/1 with the round edge and have two different screens for two different purposes.  One will bang down a great layer of ink for simpler art and one will throw down a little less ink but will hold a lot of detail and halftones.  Something to keep in mind if you hadn't thought about it already. 

[Admiral]

On my mesh chart I have exposure values for two coating methods for every mesh.  So, we can coat a 150/48 2/2 or 2/1 with the round edge and have two different screens for two different purposes.  One will bang down a great layer of ink for simpler art and one will throw down a little less ink but will hold a lot of detail and halftones.  Something to keep in mind if you hadn't thought about it already.

We don't have any idea what the EOM is but I'm pushing a consultant to get the meter for it.  Once we build our big ass drying cabinets I plan on upping the eom and having a couple different ones for the 150/48 mesh like you do Zoo, some for underbase white some for great fast printing coverage of darker inks on light garments.  150/48 mesh is just so nice...

[Rockers]

I was just looking yesterday for an EOM gauge. Asked my Ulano sales rep and he came back with a price of $600. Are they all that expensive? And more importantly are there any other manufactures apart from Ulano and Kiwo who make them?

[alan802]

I think I paid $250-300 for mine.  I got to see and use a $1000 one this weekend and it was very nice, but the results I got with my cheaper unit were very close to the higher priced one.

[blue moon]

I was just looking yesterday for an EOM gauge. Asked my Ulano sales rep and he came back with a price of $600. Are they all that expensive? And more importantly are there any other manufactures apart from Ulano and Kiwo who make them?

Douglas Griger suggested a ballpark $600 unit as the one to get (he generally tests a lot of things and provides an option based on thorough evaluation). As Alan said, they do start at $250-$300 and the tech rep that was here had a $1200 unit, but I would be pretty happy with the cheaper one. I thought I can get away without having one, but now I know better. It is going on the list (a rather long one) of things to get. . .

pierre