using new emulsion

[stig]

just moved from philadelphia to arizona and I was used to using ulano tlx. out here the screen shop suggested qx-1(he doesnt carry the tlx) but I am unfamilier with it. in philly I used a 300 watt bulb @20", or 2 40 watt florescents at about 40" for 20min and it always worked out. I use a scoup coater and apply one coat,flip 180 and coat other side. let dry 1 or 2 days and then burn. did the same with qx-1, but had to play with burn time. this time I used the 300 watt and got it down to 2-3 min and it almost worked, but just as the image was coming out it completely washed off screen. recently had new screens stretched(155 mesh) but did not clean screen before using(my bad). also washed outside, but in the shade. I cleaned and degreased them and am ready to try again. so did I mess up by not cleaning the virgin screen and washing outside. is there more I should know about this new emulsion?

[NeroInferno]

With every emulsion you work in the same way. You simply have to make an exposure test to find the new right exposure time. I'm not in the USA and I don't use Ulano, however if the emulsion is the same type like the tlx(diazo based I suppose), you'll work in the same way.

Fabio

[Andymac]

more time. your lights sound like shit,(not much UV, that's what hardens emulsion) sorry to say on christmas day.
the cleaning thing might be part of the problem. Double the time to start, or do a step test on the next exposure.

[gozo]

May I hi jack this thread and wish all gorgonzola lovers a Merry Christmas.

[huthbot]

Lots of variables there. Sounds like you are under exposing the screen but there are a few reasons why under exposure could happening. Could be new screens, new mesh color ( though I have never had a problem with burning screens right out of the box) new emulsion can be a problem if its a photo-polymer verses a diazo base then its just a matter of working out your burn time, remember any wattage and type of light will expose a screen eventually you just have to find out what is most efficient for your process. I think you also need to look in to how your humidity and temp has changed from PA to AZ. I am in Denver so its not as warm here but we have similar humidity levels and this summer was hot. I found that I cooked my emulsion a few times in the dark room. If the emulsion gets above 90f you can really have some problems. I would suggest using one of the more readily available emulsions like a Ulano 925wr (wholesalers will send you samples to test with). I would say you should get a lower wattage bulb either a set of 40w UV black lights or some 52watt white fluorescent bulbs ( easy to pick up from hydroponic grow stores) and set them so they are evenly spaced across your exposure area and make sure they are between 8 and 12 inches from the surface of the screen. I have found overhead burns seem to work better for this and you can usually get a solid burn from a diazo base emulsion in 2-4mins depending on temperature of the room, mesh count, and how long the screen has been coated. you should be able to burn a screen after letting it cure for about 3 hours just keep it in the darkroom and keep a fan on it. There is no reason you should be waiting 24-48 hours between coat and burn.

[stig]

I know humidity is a problem,which is not really an issue in arizona. I never had a problem with the wattage before, but i was using different emulsion.I just cleaned and recoated last night and will try a burn in the morning. I appreciate all the help.

[delayed]

Why do people wait hours before using a screen after coating it?

[Andymac]

I give up. Why?

[stig]

because a) when i worked a printer I coated 20 screens at a time always waited till the next day to use them and b) whats the rush. I work at home and coat 6 screens at a time and let them dry overnight. been printing for 8 years that way and never had a problem till I changed emulsions.

[DenisMutter]

Spring for one of those halogen worklights & remove the UV glass from it & use that - you'll probably reduce your exposure by 30-50%. Plus you can warm fondue on the back of the lamp for snacking after screen washout!