No, I don't mean spray pointing foam, I'm trying to find foam that sprays thin like spray paint. I need to apply such foam in thin coatings over a large area. The gap filler and similar type spray foams wouldn't do the job. Thanks.
If you mean the foam like they shoot on the wall, you can get it in fairly small disposable sprayers but it is still a couple gallons. This stuff sprays like paint and grows on the wall. The gun isn't fancy but it is all you need.
Well, I recently made a parabolic microphone to monitor wildlife near me. I made it out of an old umbrella, which I lined with aluminum tape on the inside to better reflect the sound (the sound would have otherwise gone right through the umbrella and not reflected). Now, I'd like to firm up the umbrella's top side, which is still fabric, but I also need something that stops sound. My idea was to spray paint foam on the top. If I used the thick gap filler foam, it would start making imprints in the umbrella which would affect the way it picks up and directs sound. I also couldn't try spreading it as even that would affect umbrella shape.
Spray it with several coats of poly urethane. That will stiffen it up. Take your time, let each coat dry and lay on another until it gets as stiff as you want. Two part epoxy paint would work too if you have a way to shoot it. Thin with xylene.
He said he also needs something that "stops sound".
Some research into the attenuation properties of spray-on polyurethane and fiberglass resin vs. some of the adhesive foam pads should be done - specific to his situation of course.
I wonder what kind of balance he wants between "firming up" and attenuation.
Some fiberglass mat would sure firm it up. Maybe a combination of both, fiberglass mat and then adhesive foam over that.
Of course, if you add too much material of any kind, you run the risk of damage to the umbrella's frame, depending on the type used.
He really means "reflects sound" Commercial shotgun mikes like you see on the sidelines of an NFL game are made from Lexan. We used to make parabolic mikes using dish sleds (aluminum).
The shotgun microphones work different than the parabolic types. The shotgun is made of parallel tubes each one slightly shorter than the next and the actual mic element is behind the tubes . The parabolic reflects the sound to a point in front of the dish just like the satellite TV antennas do .
The old aluminum sleds made good parabolic reflectors. some larger aluminum mixing bowels would work on a large scale. Maybe some of the TV dishes would work ok now. Never tried any of those.
I know a guy that we call "Shotgun Mike". ;-) Of course, the OP's not asking about a shotgun mic (which I'm pretty sure aren't made of Lexan) but in any case...
He may actually mean "blocks sound" as in blocks sound coming in from
*behind* the mic. I guess that could be considered "reflection" but he may be talking about "blocking it" from interfering with what he really want's the mic to pick up.
In fact, he specifically used the word "reflect" when talking about the foil tape, then switched to "block" when he asked about covering the top side of the umbrella. Until he tells us otherwise, I'll hang on to my interpretation of "block". ;-)
I played with my old DSS dish after I stopped that service and it does work. Take the LNA off and mount a mike. You have to play around with the focus a little tho. The old dish sled works great.
Not really having a need for it I didn't mess with it much other than the proof of concept. I was really more interested in using the dish for WiFi to a camera but the HOA changed their mind about a camera at the boat ramp.
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