Should/Can we coat out in the open shop or use (dark rm environment)?

[inkman996]

I am going to do a test for myself next week. We are currently coating one gallon of emulsion a week, tomorrow I have to crack a new bucket. Currently I have four 260 screens coated in our safe room, starting tomorrow I am going to coat in the open shop when I get near the end of the bucket I am going to coat some more 260's. We have several jobs coming up that require the 260's I will both burn one from the dark room and one from the open light using both the macdermid calculator and my own calibration bar right down to 99% dots. I can then examine the dots under a loup and relay my results here.

This will be done with a bucket that has been opened several times in the open shop light through out the week. I will also make sure to burn both screens when the map is cool. I will also be sure to develope them together at the same time to control the variables as best as possible. This should work.

Another thing never ever mentioned for some reason when it concerns holding dots is how the screen is developed. I have seen people either go to aggressive with the water or not enough this is an area that is extremely important to the finished screen. Let's all remember by eye it is nearly impossible to see those tiny dots during developing so it's very easy to think your are done yet another 30 seconds might open up the final dots.

[GraphicDisorder]

I would suggest its likely it could affect it, just not so likely at the amount of time/light that are in some of these shops.  My shop is not super bright.  We coat right out in the open, lights on.  Never noticed a issue vs when we use to shut all lights off and coat that way. 

What I did notice, is that we could see what we were doing better.  LOL

Where do you store your screens?

We have a 10 and 24 screen drying/storage cabinets from Vastex.  Spendy but really helps when we need to go through a bunch of screens at once.

[Get Shirts]

Wait, heat exposes screens?

[Frog]

Wait, heat exposes screens?

Yep, that's why one has to monitor a a DIY cabinet that employs a heater or dehumidifier. (It's also an added problem, for inefficient, heat-producing quartz halogen exposure units that are not well ventilated.

100 is about tops for a lot of emulsions, at least the photopolymers that I use. Mirakami says 105, and the new Orange from Ulano that seems to be the buzz in another thread says 104, which is an even 40 in centigrade.

[starchild]

Wait, heat exposes screens?

Over a certain degree and by whom the emulsion was made, the temperature will activate the cross linking of the emulsion's chemicals.
Do a search about heat vs dehumidifier for drying screens for more about this.

[alan802]

I think we all agree that eliminating as many variables as we can is the way to go, but my reasoning behind us doing it in the first place was to help train a new employee.  She couldn't see what she was doing and I couldn't see what she was doing wrong.  Now that I don't need us to coat outside anymore, I need to weigh the pros and cons of doing it and whether or not it can or will affect us negatively.  I'm not 100% certain of either way but I'm more sure that coating under regular lighting is harmless.  I think either way of coating is going to give the same results so we will be doing it based on personal preference until someone convinces me that it's bad to coat under non uv safe conditions.  Now that are dark room is no longer dark, it won't be such a pain in the arse to coat in there any longer.  I will keep a close eye on our exposures although I completely agree that we (our shop) don't have the tools, ability or knowledge to properly test this the way it needs to be.

[Rockers]

Yes,

The argument Dan is making (if I have this right) is that even cracking it open and filling up your scoop coater in said ambient light is bad for the emulsion.

As the emulsion gets older, it gets gummier and is not the best to use for high def work. Thicker and harder to get a nice smooth coat. If I were coating for sim process, I'd switch to a fresh bucket. You can use the other older mud on your 110's

I never experienced emulsion getting really gummier unless it has not been stored at the right temperature or do you mean by older a time span of over 6 month?

[Gilligan]

Exactly eliminate as many variables as you can but it's possible to be spinning your wheels putting too much energy into something with minimal ROI.

[Rockers]

We have been coating in indirect daylight for over 12 years and never had an issue. Mind you we are using Sericol Dirasol 916/917 which is as slow as a snail. Once we had some Ulano QTX and that does not really work with coating in daylight. Saying that I think the really issues arise with the QTX once the emulsion is dry and you handle that screen outside a safe light environment. Same for the cabinet the screens are kept in. Repeatedly opening the cabinet in indirect daylight will pre expose the emulsion on the screens kept inside that drying cabinet.
But if you are worried about indirect daylight from the windows in your workspace why not use clear window vinyl that is especially designed to cut out 99% of the UV light. That way you can have the benefits of daylight in your space without having to worry about the UV light doing damage to your screens.

[mooseman]

we move QTX around all the time with no issues. Open light from dry box to storage, in & out of storage many times, transport to washout room walking directly by a south facing window just don't seem to have a problem?
Most like it is the  NY sunshine
mooseman

[Dottonedan]

Great printing results is like great art. Each persons opinion on what is great is different. None are wrong.

[Rick Roth]

As much as we all would not agree what is great art, we all know bad printing when we see it. We each might draw the line somewhere differently, but bad printing exists.

Bad printing never seems to be the result of one problem, but a myriad of problems that add up to crap.

In regard to this current thread - safelight covers cost a little over $10. Even if you had 10 bulbs in your screen room to cover that's $120. How much does one job with halftones that you wrestle with for three hours cost you and do you want to take the chance that you are not getting the best halftone dots you could have? It isn't even that you get the best halftone dots you can, more important in the long run is that you get the same halftone dots every time.

Someone earlier mentioned that all the manufacturers said that coating in a lit room was ok. You can't trust information like that necessarily. We had an exposure unit that was inexplicably to me white inside. The manufacturer assured us that if it was black instead of white inside it would not make a difference. All the units I saw in anyone else's shops were also white. We painted ours black inside and it made a huge difference in resolution because of less light scatter I presume.

[mk162]

I coat in a safe light environment since we have skylights.  Don't really want to mess with that variable.  Some days it's not bad, but others you get a lot of light through those.

[JBLUE]

We coat our screens in a light safe environment as well. We do everything possible to get that last elusive dot consistently. The other major reason we coat inside the screen room is dust. Why coat your screens in a dusty lint filled environment? Every single shop is a dust haven and even though you dont see it, its still there floating around just waiting to stick to your wet screen.

[Gilligan]

Not everyone can afford the dark room.  Some people just don't have the room.