We are having major issues with TW clogging. Our screens are properly exposed, we are soaking the screens on both sides with 70/30 water/S-034 mixture, and have even added TW's retarder. We move very quickly printing on a M&r Saturn.
So here is my only guess- We use CCI SWR-3 emulsion. Could it be that this emulsion reacts poorly with TW? Is there an emulsion you would recommend trying?
No need to soak the underside of the screen, just squeegee side.
I know you say your screens are properly exposed, but you could be experiencing scumming from excess/unexposed emulsion on the squeegee side. It doesn't take much. After your initial stencil washout, give that side a gentle wipedown with a soft rag and wash again.
Is your squeegee dull?
I have never heard of a dual-cure emulsion 'reacting' with a water based ink; that seems far fetched. I use Murakami Photocure Pro and recommend it.
What mesh count are you using? I have no issues with TW 5000 drying in on my 230 mesh screens when mixed with a little water and a little halftone clear base to a normal "pancake batter" type consistency. But if I use that same consistency on my 280 mesh screens I have all kinds of problems and have found that I have to thin it out quite a bit with water so it's pretty runny to get a good print through a 280 with no clogging issues. Try adding more water until it seems too thin and give it a try.
The emulsion you're using is a dual cure that is supposed to have good water resistance...doubt thats the problem unless you aren't exposing fully. I use Ulano QX-5 Blue which has just so-so resistance to some water based inks and I don't have problems with it breaking down with TW until I get up in the couple hundred prints range.
I don't think there's any need to wet the bottom of your screen. Just the top. Wetting the bottom seems like it would cause all kinds of other problems.
If I were you I would ditch the retarder....I've never needed it. Mix up a fresh batch with a healthy dose of water and give it a shot.
Stick to 230 mesh or coarser for WB inks. You can go up to 305 but it's too much of a hassle to print with WB inks so I don't bother.
As stated above, do not wet the print side of the image. This is hurting you more than helping. Wetting the back (and really soaking the front) allows the ink to prematurely get onto the underside of your screen. Any ink on the back of your screen with hinder the screen from clearing completely.
Is your Saturn set to be flooded when at rest? It's VERY important that it is when printing WB inks.
Is your screen clearing completely? Try increasing the pressure. I know this seems counter intuitive but increase your flood pressure (proper flood pressure should seem dangerous in the amount it depresses the screen). You want a nice thin flood. Increase the angle of your flood (less deposit) and double check the angle of the squeegee. Raise the peel if needed and double check your off-contact. Make sure the vacuum isn't sucking your screen to the table.
Lastly some cities have PH and mineral content in their water supplies that actually speed up the drying of the ink. Go to the drugstore and get a gallon of distilled water. Put the distilled water in a spray bottle and use that to wet your screen before the run and during. Dry days and/or thin lines can require lightly misting the screen every 25 prints.