Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
I'm a capillary film user and I have to hit them with a good scrubbing of mesh abrader. I hate doing it, but it's the only way I can make it work. After the first couple of rounds with a new screen they coat/expose like normal. It was pretty stressful for us as we swapped all of our screens over and couldn't get anyyhing to expose. I'm curious to see what others have to say. I just assumed it was because I'm the odd cap film user.
if you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.pierre
Quote from: blue moon on January 27, 2016, 12:23:31 PMif you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.pierreRight. Usually we would coat 1x1 with the round side. We have been trying 1x1 sharp side on 150s with slightly better results but still getting some slime. But we did also try increasing our exposure, in our initially test we doubled our exposure times and still getting some slime. Maybe the screens weren't dry enough? we try to give them a good day of dry time after coat. Although we have our screens in a decently controlled environment I've noticed they are still affected by our weather... if it's super hot and humid in the summer we were fighting to keep the humidity down in the screen booth and also since it's been a lot colder we recently bumped up the heat... There was another topic recently discussing the colder weather and exposure times.It all made me wonder if the s-mesh are just more sensitive... or am I just realizing that screen making in general needs to be more precise and conscious part of the process... everything with our Tmesh was easy... rarely any issues.
Quote from: Maff on January 27, 2016, 12:51:01 PMQuote from: blue moon on January 27, 2016, 12:23:31 PMif you coat the T and S the same, S will have almost twice the thickness of the emulsion and you will have to increase your exposure times. Keep burning until there is no slime on the other side.pierreRight. Usually we would coat 1x1 with the round side. We have been trying 1x1 sharp side on 150s with slightly better results but still getting some slime. But we did also try increasing our exposure, in our initially test we doubled our exposure times and still getting some slime. Maybe the screens weren't dry enough? we try to give them a good day of dry time after coat. Although we have our screens in a decently controlled environment I've noticed they are still affected by our weather... if it's super hot and humid in the summer we were fighting to keep the humidity down in the screen booth and also since it's been a lot colder we recently bumped up the heat... There was another topic recently discussing the colder weather and exposure times.It all made me wonder if the s-mesh are just more sensitive... or am I just realizing that screen making in general needs to be more precise and conscious part of the process... everything with our Tmesh was easy... rarely any issues.how long are your exposure times? I would expect a 3min +, possibly 5 with an 850W and 150S.pierre
Also, what do you think about abrading s-mesh... anybody else doing that?
When we switched from T to S mesh, we had all sorts of issues, and it took us a LONG time to get things sorted out. At first we blamed the emulsion, and in a way it IS an emulsion issue, but more due to how the emulsion interacts with the mesh.The intermediate story is long due to all of our testing... for that, I apologize.To start the story:when we switched to S-Mesh we started having edge breakdown and wear issues right out of the gate, sometimes even breaking down 5-10 shirts in to the run. you could actually hear the screen 'crackling'... We had changed to S-mesh in the winter, so the first thought was the SP1400 we were running was prone to issues in low humidity so Murakami had us try SP1400-W (a winter blend for SP1400)... the issues continued, not quite as bad, but still there, we started taping on the top of the screen well into the squeegee path... again, we'd still have issues (anybody who's met Tiffany know's that she's a tape nazi (no tape for you!) and she was complaining about all the tape... and heck sometimes the cracking would follow the tape into the rest of the image area, especially on long runs.Somewhere around this time I started thinking that the Starlight didn't have the 'punch' to get through the screens successfully, this was totally incorrect, as the screens are being initially exposed correctly (solid 7 step), when we were having issues, we kept on adding time as well thinking more exposure would help (it didn't)* we started playing with different types & brands of emulsions with differing results, but we still had wierd issues...We did sun exposures with several different emulsions to prove out that the initial exposure wasn't the issue...Then we switched over to Saati PHU-2, had the same issues, and started some major in-depth testing in the shop.1. We got the exposure times dialed in better (they were concerned as we were over-exposing our screens, by 2 steps on the strip) -- better detail after that, but no better results on press.2. We found that a 1/1 on the S-mesh (even 225S!) was resulting in 50% or more EOM. We did a ton of testing here, until we finally found that 1 coat on the shirt side was all that was needed to achieve a repeatable 20%-ish EOM. -- no better results on press.3. We started post exposing... tried Starlight, saati 300W LED, and sun post exposure. While the Saati 300W and Sun post exposure seems to result in better discharge/wb/hsa screens, for any plastisol work, there was no better results on press.4. We started using Saati DirectPrep2 on our screens... no fish eyes, pinholes, water marks, anything after that, and the emulsion coats even smoother... but no better results on press.*** It's important to note that through ALL of this, our older T-thread mesh screens were having NO issues. This should have been a sign, but really with everything else going on, it didn't click.FINALLY after at least a month of testing... Saati has us try Direct Prep 1 which is a light mesh abrader... at first I questioned this as "nobody needs mesh abraders anymore" seems to be the advice of everybody.The first set of screens onto the press showed an immediate improvement, and since then, we've had no issues.After talking with Saati, we think the issue is a emulsion adhesion to the smooth smesh, and with the fact that there's less thread diameter for the emulsion to 'grab' onto, we need to 'rough' the mesh up a touch with the abrader to get better mesh adhesion, and that was the issue...
What emulsion are you using. And what exposure times do you have for your standard 150 mesh?
***BIG NOTE FOR ALL THIN THREAD MESHES****Because you have less surface area/thread area for the emulsion to grab onto, it is easier for the emulsion to release on the stoufer strip. Thereby giving you an inaccurate reading about "full" exposure. You can easily end up with a solid step 5 or 6 when it should be 7.A lot of this is determined by how long the screen HAS BEEN ABSORBING/SOAKING up water. The more chance it has to soak up water, the easier it is to release.