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Condensation problem

  1. Aug 6, 2013 #1
    Im on the tech team doing an outdoor concert series. I have a dance show coming up this weekend and Im having a hard time keeping the stage dry. Its a nice big black stage radiating its heat away at night and around 9 pm it starts to get a bit wet and slippery (very no bueno for dancers) I can't use gas or propane heaters because of the fire hazard. I can't use any electric heaters as we have limited power and every last amp is being used for sound and lights. half of our lights are running off 104 volts due to the lengths of the runs): I painted the top of the stage with black latex paint and it helps a little by I think both filling in the textured surface a bit and reducing the surface area slightly, and the paint itself has a higher coefficient of friction then the stage has unpainted and is less slippery when wet. but on the colder evenings its still a problem and it gets quite wet. the stage is about 4 feet off the ground and I have been thinking about putting stainless steel barrels or aluminum kegs filled with water under the stage to act as heat sinks and passively help regulate the temperature. any suggestions would be appreciated
     
  2. jcsd
  3. Aug 6, 2013 #2
    Roll out carpet insulation at night?
     
  4. Aug 6, 2013 #3

    berkeman

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    Staff: Mentor

    Instead of black latex paint, you could use boater's deck paint. It has stuff in it that gives it a good texture, and you get pretty good traction even when wet (hence why it is used by boaters). I got some at Sears or OSH (don't remember which), and painted my dirtbike trailer floor with it. It worked great. Note that you put on two coats, using a roller in two different directions for the two coats.

    EDIT -- And it uses a special roller. Check the paint can directions to find out which one to use.
     
    Last edited: Aug 6, 2013
  5. Aug 6, 2013 #4
    Add some fans to blow air over the stage to try to keep the stage temperature above the dew point.
    Add a canopy over top so there is less radiation directly into space.
    Your idea of heated water in barrels underneath is good. Insulate the ground and around the sides so the only way for the majority of heat to escape is up through the stage, warming it. You want to minimize air flow so try to seal the stage off as best as possible.
     
  6. Aug 6, 2013 #5

    russ_watters

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    Can you locate any of the electrical equipment under the stage to heat it from below?

    P.S. If this works, I want free concert tickets: I don't care who or where, I just want to be able to tell people I got free concert tickets for solving an engineering problem on the internet.
     
  7. Aug 7, 2013 #6
    @russ_watters the audio amplifiers and Rf rack are under the stage, the section of stage directly above them does stay slightly dryer, but not by much . and if you want to come for a show im in sonoma county CA and we have 3 more weekends of shows this season. you can come to a show wether or not you solve my problem.
    @berkeman. i like the boaters paint idea. Im not sure how thick it goes on or how rubbery it is and i dont want to change the sound quality of the stage as we have several tap numbers in the show. but if you dont think that this would be an issue ill try and find some today.
    I did find a 55gal stainless steel barrel im going to put under the center of the stage today and i'll see how well it works for that area. if it works i'll contact friends at some of the wineries and borrow some more for the rest of the season.
     
  8. Aug 7, 2013 #7

    berkeman

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    Oops, I don't think tap dancing will work on the boat deck paint. It's not quite like sandpaper, but it has a pretty high-friction hard texture.

    [hijack]
    It's cool that you're up in Sonoma. I went through high school in Calistoga, and I was up in Windsor a couple weekends last month helping out on the medical team for the Vineman Ironman Triathlons. :smile:
    [/hijack]
     
  9. Aug 7, 2013 #8

    russ_watters

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    Can you enclose the area under the stage to trap the heat?
     
  10. Aug 8, 2013 #9
    the barrel with water I put under the stage didnt keep that section dry. I'm really disappointed about that. this morning I found an anti slip paint additive made from crushed walnut shell at a local paint store. I'm going to mix that in with the outdoor latex paint I'm using. Its not nearly as course as the aggregate used in boat deck paint. (Id guess its around 100-120 grit if it were sandblasting media)
    Im not sure why but it seems to be the thermal properties of the textured plastic or mica veiner of the stage sections that allows or encourages the condensation. Ive made some plywood risers that Ive placed on the stage and have had no condensation on them at all.
     
  11. Aug 8, 2013 #10

    marcusl

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    The plywood might be absorbing the dew/condensation, while it pools on the plastic making it slippery.
     
  12. Aug 26, 2013 #11
    we solved the condensation problem by using a 80,000 BTU propane forced air heater. I rearranged some of the power runs and made some more headroom on our backstage circuit. the fan on it only draws 1.5 amps continuous and if it does trip the breaker we wont lose any of the sound or lighting used in the show. its also much quitter then I expected so its not a distraction. the flame is completely contained, but to be safe I placed some plywood and cinderblocks on the ground and the heater on top of that and except for the vent none of the exposed parts of the heater get warm so feel it poses any fire hazard. I tied tarps around the whole perimeter of the stage to help seal in the warm air. I turn it on at intermission and let it run full blast the during the second act. I haven't used a thermometer but the air under the stage feels about 20 F warmer then ambient. the end result is a completely dry stage and no dead dancers. I was just hoping that there would a more scientific way of solving the problem. for as smart as we humans think we are in this case blunt force was the solution. in the end the stage is dry from burning dead plants and I'm no better then a caveman.
     
  13. Aug 26, 2013 #12
    Using and engineered forced air, propane heater seems less scientific than stuffing a bunch of warm water buckets under the stage? :bugeye: haha
     
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