MAKE author Steve Lodefink remade one of those cool n’ fancy vapor projection screens you’ve likely seen in used for special effect video display –

If youâ€™ve ever ridden the Pirates of the Caribbean ride at Disneyland, you will remember how, right before you hit the first drop, you are greeted with the ghostly image of the tentacle-faced Davey Jones creature warning you that â€œdead men tell no talesâ€. I certainly did.
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I have no idea how the commercial fog screen makes those glass-smooth sheets of air, but all I could think of was to shoot the air through some drinking straws. I made a little box-jig and hot-glued up some bricks of 2 inch straw sections. I then chained those bricks together into long vents. It does straighten out the airflow quite a bit, but certainly does not produce a laminar flow.

Well, it looks pretty impressive from here! Head over to Finkbuilt to see how it’s done – DIY Fog Screen

## 12 thoughts on “DIY Fog Screen”

1. Mohonri says:

It’s not just the fog itself that needs to go through the straws. Think of the videos you see of cars in wind tunnels, where they let out a line of smoke to see how aerodynamic the vehicle is. If you want to get a nice sheet, you need to flow the surrounding air the same way. So take the long block of straws, make two more like it, and put one on each side. Flow smoke or mist through the middle one, and air through the other two. The two outside sheets of air will contain the flow of the smoke in the middle, keeping it in a much more orderly sheet.

2. Teancum says:

Another factor is the speed of the airflow. The faster the airflow, the less time the smoke/mist has to dissipate, and the less noticeable any imperfections become.

3. Threebean says:

You may also need a bank of fans that draws the vapor down.

4. Anon says:

If you want to create laminar flow you need to make sure that the Reynolds Number of the air flowing is less than 2100.

Reynolds number is a unit-less number found by the formula

((Vx bar)(D)(rho))/(eta) = Re

rho is the density of the flowing gas/fluid
for air at room temp: rho = 1.177 kg/cubic meter

eta is the viscosity of the flowing gas/fluid
for air at room temp: eta = 1.85 * 10^-5 Pa*s

D is the diameter of the pipe
(Vx bar) is the average velocity of the gas/fluid

thus if you measure the diameter of the straws you used and you set Re = 2100 and solve for Vx you can find the absolute maximum velocity your gas can flow at before becoming turbulent.

I’ll bet if you scaled down the speed of the flow or increased the diameter of the straws you would be able to create your fog screen.

The density and viscosity of the fog will be different than that of air but the values I have given you will be a good place to start.

Happy Making

5. Neethu says:

dis is Neethu..am doin my final year engg in ISE….as part of my academics i need to give a seminar in d coming week..d topic “FOG SCREEN” interests me a lot n i wud like to give d seminar on d same topic
pls do send me d ppts n pdf…i ll be very thankful to u…

regards
Neethu