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

[Frog]

I think the bottom line of this discussion/debate is establishing a benchmark of the ideal conditions to coat, expose, and store screens. Those printers, who probably make up the majority of the industry in sheer numbers, can probably cut a lot of corners and never notice a difference on their non-demanding work.
Hell, there is even a segment that starts with hand-held screens, and curing with a heat gun, and exposing screens in the sun. Perhaps a big step for them is a home built press, and a flash panel.
To them, a $3000 investment in a used commercial quality press and belt dryer seems like a crazy pipe dream. With luck, that changes.

It's a matter of how close to the "state of the art" they wish to advance, and frankly, whether the investment will pay off in both better, more consistent results, as well as financial gain. Not everyone's market requires the sophistication of our top shops, so other factors may have more wiggle room as well.

In the end, hopefully, we all do what we can do with what we have, but keep growing.

[JBLUE]

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

I totally understand that. I started in the garage and used our second bathroom as my screen room at night while everyone is sleeping. I know tight space. There is always a way to get the job done. I coated screens after dark and woke up early to put them in garbage bags. The point is that if you have the room use it. if you dont have the room then accommodate the best you can. No matter how small a shop you have you can make the right environment some how. 

[Dottonedan]

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

I think you make of it what you will. I'm sure some places are maxed out on room in a shop.

For me, I am currently gathering the remaining necessities (screen cleaning/reclaim, etc. ) for the shop in my garage. My dark room (where I will coat screens) will be 4' wide by 9'. Like a long closet.

I want to thank everyone for the great communication and informative posting on this subject. I don't think most thought it would be a controversial topic worth so much effort to discuss. Some still don't think so, but it was a good thread none the less.  I am anxious to see Inkmans results but at the same time, his results would only be a contribution to what needs to be a group of results.

[inkman996]

Dan there is a reason I hesitate to even bother with a test like I spelled out and that is no matter the results there will still be nay sayers no matter the results. Yet i feel what I am going to do is more than sufficient to prove or disprove this whole discussion. It is exactly as you laid out Dan going through a whole bucket of emulsion in an open light area through the course of a week. At the end i will expose and develope all range of dots and the calculator, if I see no difference between the 260 coated in our dark room versus the one coated in the open light room I will consider the myth debunked.

[Gilligan]

Hell, technically the "UV safe" bulbs in your dark room aren't 100%.  Do the ol' coin on a screen trick and see for yourself.

So now, you need to coat and preregister in complete blackness to keep your emulsion 100% effective.

[Dottonedan]

Dan there is a reason I hesitate to even bother with a test like I spelled out and that is no matter the results there will still be nay sayers no matter the results.

I think we all feel/see this coming.  Simply because it's still left open for variables and only one shops results.

I feel if proven to have a 1 or 3% dot loss, some will still not change a thing. Some because of the effort and some for the lack of feeling a need to add another 3% dot. Many do not achieve holding a 5% dot let alone 3 so it won't matter to them. Some do'nt burn halftones higher 50lpi and less than 5% dots so it won't matter to them.

I think tho, we will have many, many more happier people if it's proven that regular shop lighting does not affect the results at all or "enough to gain or lose a few dots.  If this is true, then I will also be coating out in my regular light just for the room.


None the less, your results will be a great contribution for you especially. Your one result should not be considered hard factual evidence but considered one sample specimen. It might be conclusive evidence (for your parameters) but not for everyone (in general or as an average).

We should ask for a group of at least 3 or more players. That should not be hard (since we have far more people in here that do coat out in the light).

[JBLUE]

Hell, technically the "UV safe" bulbs in your dark room aren't 100%.  Do the ol' coin on a screen trick and see for yourself.

So now, you need to coat and preregister in complete blackness to keep your emulsion 100% effective.

I can tell you that my bulb is 99.99999& uv blocked. The light in our screen room stays on for 12-14 hours a day. I just used a 305 last week for a job that has been sitting in there fo 6+ months and it exposed just fine.

You might want to get a different light source if you are having that problem.

[Gilligan]

Honest question, was the screen out in the light that whole time?

The test that I've seen conducted is to leave a coated screen out on a table (completely exposed) with a coin(s) taped on the screen.  Then after X days wash it out and see if the coin spot washes out differently than the rest.

You can take this further and put multiple coins and remove one a day blah blah blah to see the time frame that it took.

If you screens are/were in a cabinet or stacked or anything that would "shade" them, that could be a difference.  Plus, you didn't have the coin on there and getting it to expose fine is relative as Dan has been pointing out.

[inkman996]

Amberlyth and rubylyth loses its filter properties over a period of time, we used to own a UV meter that told us the exact UV being emitted in to the room. Even with brand spanking new amberlyth UV is present none the less it is so freaking neglible for our process it is safe, if working with camera film and developing UV even a negligible amount is an issue.

Dan I am trying to show or prove no loss of dots versus you keep talking about gaining x amount of dots thats not what i am doing, my point is to show in a working day to day shop the out side shop lights will or will not effect enough whether you are in a dark room or not. Simple as that.

[Dottonedan]

Dan I am trying to show or prove no loss of dots versus you keep talking about gaining x amount of dots thats not what i am doing, my point is to show in a working day to day shop the out side shop lights will or will not effect enough whether you are in a dark room or not. Simple as that.

I think we are talking about the same thing in a different way apparently.  As I see your desired results as being the same.

Lets say (since I don't have any hard numbers of what you achieve on a normal every day basis). Lets say you can normally achieve a 60lpi halftone and go down as far as 6% with no issues. 5% usually causes saw toothing er something (in the screen coating room with protected lighting). Now, with this test, your normal procedure (should not change).

If you then coat out in the shop under regular flo or whatever lights above (window or no windows). Over a weeks time of coating screens under regular lights, (the halftone screens coated from the emulsion at the last day of the week) should show an adverse affect (to some degree) and I am saying that degree might be losing 1-2% dots (using the same exposure times) as you normally do in both cases.  Will this be an accurate test?  Should be, to some degree.

I think that 1 gallon is not going to show as much as it would, had you used a 5 gallon bucket and did the test over 5 weeks. For example, on a 1 gallon, you might only see a 1% change (and that is not really worth celebrating a win or loss over). On a 5 gallon over 5 weeks, you might see a strong measurable difference such as a 4% difference (lets say).

An easy way that someone might compensate for this (for anyone) is to say, gee, my 5% dots are not coming out great. Maybe my exposure times are off? So, maybe you do an exposure test (using the pre-exposed screens) and the results show that you are over exposing your screens a tad. So you cut back on exposure times just enough to hold more dots. Now, as a result of that, your stencil might be slightly under exposed and may not hold up (as well) as it truly could have with an accurate exposure. So when you get that long run of 3-5000 shirts and the screen starts to break down at 1500, you might ask yourself, why?  This might be why.

For this reason above, I am thinking that not only might you add 1 or 3 more dots, but you might also strengthen your stencils more for longer production runs, resulting in less interruptions of production flo due to screen breakdown. Just a guess, but makes sense.

[alan802]

I'll do the testing as well, I have a piece of film that has all kinds of levels of halftones, 1-100%, 20lpi-85lpi, etc.  I'll just use that film to test this on some high mesh counts, maybe 280, or perhaps a 330 S thread would be better for this test.  I have 2 of those that we rarely use so that's probably the way I'll go.

If I'm getting 98.3% of my halftones to stay, and coating in safe light will move that figure up to 99.7%, then I'll change.  If it increases it by a few tenths, probably not worth it, even though it's not that much harder to do.  I won't be counting these halftones and the results will be looked at through an 80X lighted loupe so the results will be by the good old human eye (with a little help).

[Dottonedan]

I have a piece of film that has all kinds of levels of halftones, 1-100%, 20lpi-85lpi, etc.

Great!  I have what amounts to the same test sheet that I send to people to determine what the are really holding. I have them burn it on a 230 or a 305 and look around the 50-60 lpi section. Some are very surprised. Many aren't holding the 8-10% range. One was losing under 14%.

[inkman996]

I am actually pleasently surprised at the percentage I can now hold since we got the MSP. I know i am hitting 5% easily probably lower if i take the time to examine. But the macdermid calculator has 10% 50% and 90% at 65 DPI and i nailed them perfectly on a 260 that to me is a good sign

[Prosperi-Tees]

I have a piece of film that has all kinds of levels of halftones, 1-100%, 20lpi-85lpi, etc.

Great!  I have what amounts to the same test sheet that I send to people to determine what the are really holding. I have them burn it on a 230 or a 305 and look around the 50-60 lpi section. Some are very surprised. Many aren't holding the 8-10% range. One was losing under 14%.

Hey Dan, I would be interested in that test sheet. I wonder what I could accomplish with 240 watts of UV tubes.

[Gilligan]

... the results will be looked at through an 80X lighted loupe so the results will be by the good old human eye (with a little help).

Geeze, I can't imagine what that would look like.  I have a 10x and 15x loupe here that I picked up for dirt cheap mostly as a toy after seeing you guys talk about them so much.  I was blown away by the difference and how amazingly close the 15x gets... so if a 50% increase did that I can't even imagine what a 500% increase on that would be!  I mean I was looking at 4 color process "dots" on the Anvil swatch book and was amazed that it got that close, with 80x what are you seeing the fibers of the paper?! LOL