UV output affected by room tempertaure?

[Rockers]

I might be barking up the wrong tree here but recently we experienced real problems with our screen exposures. our screen making room is getting pretty cold over night and at day time too. Let`s say around 42F. Coated screens are kept warm though in a heated cabinet. Still our Vastex LED exposure unit does not manage to burn a screen at the same exposure times we use during spring, summer or autumn. I have to almost triple the times otherwise the whole emulsion washes right off the screen. I did  a comparison on our our MSP 3140 and what I noticed is that at these low temperatures the LTU count down a lot slower at the beginning of the screen exposure, around 3 sec/LTU around 15 sec into the exposure things begin to speed up and the LTU are at what`s normal for our shop at around 1 sec/LTU. Then we did brought a big stove into our screen making room to raise the room temperature to a nice 68F and boom no more problems. LTU on the MSP3140 were not as slow anylonger and the Vastex LED unit did perform as well at the speed we experienced during summer month. Now the guys at Vastex don`t believe there is any connection between temperature and UV output and as I`ve said I might be totally wrong with my conclusion. Maybe someone with more knowledge like to share his thoughts on this matter.

[SoccerMom]

   I would have to disagree with them on principal, Vaacuum tubes (or valves for you old guys ) actally worked on this premise, Boil the electrons with a heater and they become agitated, hence the warm up period.... Back on topic, I would assume this is the basis of a M/H bulb, again requiring a warm up period, Light energy would be the final output and in theory could be made less efficicent with cold.

[Rockers]

Just noticed now while exposing the first screen of the day on LED unit that the blue light that indicates the unit is exposing came on but the LED lamps actually kicked in 10 seconds after that.  Probably because they were still too cold from the night before. This should really not be happening on a unit like that.

[alan802]

I guess there is a chance the problem could be outside of the expo unit.  We've had almost no winter this year and the coldest temp the dryer has shown at startup in the morning was 40, so I can't test our unit until the next cold spell and it sure doesn't look like that is going to happen until next year...crap.  That just means this summer is going to be brutal, can't wait.  If we do get lucky and have some cold weather within the next few weeks I'll see if our unit has any issues, other than the usual. 

[GraphicDisorder]

In our warehouse see around 35 in winter to 110 in summer. Our Starlight is in our warehouse in those temps and we've seen no problems.

[Rockers]

In our warehouse see around 35 in winter to 110 in summer. Our Starlight is in our warehouse in those temps and we've seen no problems.

Which is the unit I originally wanted to buy but because of the long turn around times I had to shop somewhere else. Wow how much I regret it now.

[Maxie]

Brandt, How can you work in those temperatures, freezing or boiling hot.

[GraphicDisorder]

Brandt, How can you work in those temperatures, freezing or boiling hot.

My office has heat and air is how... haha.

Winter is actually pretty great once the dryer comes up to temp a bit. But we can't run heat out there at night/weekends for no reason. Summer no way we could economically cool 6,300 sqft of barely insulated warehouse with 30ft ceilings.

[GaryG]

Was looking at some Big A$$ Fans, but got some Hunter Fan industrial fans that bring heat down
from 20' ceilings and it has to be saving us a good bit. You wouldn't believe how hot it is at ceiling height,
but only 65 or so (set on dial) at floor level.

It is so much more comfortable when that top heat is directed down to working level. They turn slow but push volumes.
You can tell a difference every day, and termed "Destratification" I learned form the $3,500 fan guys.
Hunter Industrial 8' fans = 2 @ $925ea

Thread topic- looking forward to a Led one of these days, our MSP3140 is humming along just fine.

[Vastex]

Just noticed now while exposing the first screen of the day on LED unit that the blue light that indicates the unit is exposing came on but the LED lamps actually kicked in 10 seconds after that.  Probably because they were still too cold from the night before. This should really not be happening on a unit like that.

This is actually the first time we have heard of a delay for the light to turn on one the control panel tells them to. We have tried to replicate possible issues with the temperature since it is below freezing and haven't seen the same problem. The problem doesn't look to be the lights so we have narrowed it down to the power supply that independently powers the LED bulbs. We are replacing that and are going to do everything possible to make sure the exposure unit is working properly.

It is possible for a lot of variable to affect the exposure time such as room temperature, altitude and humidity. Emulsion doesn't like colder temperatures and that is why emulsion suppliers won't ship it when temperatures outside drop below freezing. I learned that the hard way when I used to print out of my garage and I ruined a new gallon of emulsion because it froze.

[ABuffington]

Is the emulsion colder than usual when you begin to coat?  If so EOM may be far greater in cold rooms than warm spring/summer rooms.  This would cause underexposure if times are not changed. You can place emulsion in a small hot box overnight to keep temp at 60-72 degrees.

Al