What would cause this to happen

[rmonks]

Even though other's may say I'm wrong IMHO your not going to vac enough water off the screen to go straight to coating if your doing that, water has a way of hiding in crevice's and running down the screen when you least expect it (been there trying to hurry a screen).

No they had dried for 14hrs or so with a dehumidifier going prior to coating. This is my first experience of this and it has only happened with the LX-680, and the 83 mesh , so I'm going to go back to my QX-1 and see if it happens.

[Frog]

Interesting, as they are both 38% solids. I would have guessed that the problem was with much less solids with the LX 680. They don't state the viscocity of the LX-680 to compare, but perhaps that could be an issue.
Did you say that you have been successful in the past with the QX-1, same coating, same mesh, same drying?


btw, most of us will take exception to your coating method as it is pretty well accepted to end on the squeegee side to force the coat out to the substrate side where it does its job.

[Homer]

it appears to me the streaks are caused by the emulsion running down the mesh. If you look at a streak, at the end of it there is a bubble of emulsion. so a giant emulsion "bubble" is running down the mesh, pooling, then forming a drip....my take anyway....still way too much emulsion.

[3Deep]

For the emulsion to pool it has to 1 been set on an uneven surface, 2 the screen is loose,3 the screen is warped causing the emulsion to run....crazy how things happen and you can't explain it so you'll know next time.

[rmonks]

Interesting, as they are both 38% solids. I would have guessed that the problem was with much less solids with the LX 680. They don't state the viscocity of the LX-680 to compare, but perhaps that could be an issue.
Did you say that you have been successful in the past with the QX-1, same coating, same mesh, same drying?


btw, most of us will take exception to your coating method as it is pretty well accepted to end on the squeegee side to force the coat out to the substrate side where it does its job.

Yes that is correct. The QX-1 Did not do this.

[Printficient]

What we have here is a failure to Xenonicate

[alan802]

I've seen emulsions that were supposed to have the same solids content but be completely different viscosity wise.  38% is low in my opinion and it wouldn't work well with most of our thin thread mesh with big open areas.  We had the Ulano Orange do this on one of our 83/71 with a 2/1 coat but when coating it again with Saati PHW Red it didn't happen.  I bet the 680 is a lot more runny when pouring it out of the bucket versus the QX-1.

[Frog]

I've seen emulsions that were supposed to have the same solids content but be completely different viscosity wise.  38% is low in my opinion and it wouldn't work well with most of our thin thread mesh with big open areas.  We had the Ulano Orange do this on one of our 83/71 with a 2/1 coat but when coating it again with Saati PHW Red it didn't happen.  I bet the 680 is a lot more runny when pouring it out of the bucket versus the QX-1.

Yep, and unless I merely overlooked it, (I was really rushing) the LX 680 did not even list the viscosity on the tech sheet.

For coating purposes, I have known folks to refrigerate their emulsion to thicken it up, but whether, in the drying cabinet, it would thin and run before starting to set, I couldn't say.

[rmonks]

I've seen emulsions that were supposed to have the same solids content but be completely different viscosity wise.  38% is low in my opinion and it wouldn't work well with most of our thin thread mesh with big open areas.  We had the Ulano Orange do this on one of our 83/71 with a 2/1 coat but when coating it again with Saati PHW Red it didn't happen.  I bet the 680 is a lot more runny when pouring it out of the bucket versus the QX-1.

Yes it is runnier. It works fine on Higher counts, which is what I purchased it for hoping to get better results with halftones.

[Lizard]

The only time I have ever seen this is when screens are stacked on top of each other after coating where there is no air flow between the screens.