My teacher and I are having a fight in class about whether or not you can spray paint a motion sensor to not set it off Answered

It depends on how sensitive the motion sensor is. Is this like a laser tripwire, or (Cannot disclose government briefcase sensors.) like a sectional sensor? What kind of lens does it have? Is it IR, heat sensor, UV, UVA, UVB, or otherwise? It depends on the kind, but overall, if it was in use, then sprayed, it would probably be set of. There really isnt a way to not set it off, other than cutting the power, Opening it , cutting the BLACK wire, Insantaneous extreme shock, or smashing it somehow creating a EMP, (ElectroMagneticPulse) -RoAr

If you were going into a business, home, anywhere there is a motion sensor and the system is off because it’s open. Use a can of name brand clear spray paint, and spraying only the aluminum colored piece or the sensor piece but not to heavy to many it run. Come back two or three times covering it again. Then using three or four pieces of HVAC aluminum tape, most sensor areas are aluminum colored cut the tape down to fit over the sensor. Not super clean but try to make it look as natural as possible. The clear coat will stop the movement and the tape with shut down the IR as long as you don’t stand right in front on it or light a cigarette in front of it.

On an episode of mythbusters they defeated a motion detector by walking slowly behind a bed sheet the person walking was holding in front of their body.

It definatly would. A motion sensor detects objects in a room, detects miliseconds later (cheap ones might detect again seconds later), and compares the two "images". If they are different, within a certain threshold, it will go off. Spray painting it will make a drastic difference, and even the cheapest and least accurate sensor would go off then.

cover the sensor and the area of the wall around it with transparent plastic bags. spray and see what happens the sensor sees the room diffused thru a fresnel lens. i think it reacts to change in IR pattern once you painted it in a nontransparent for ir layer of paint it will stop working. but as benthekahn said the act of painting itself (or getting to the sensor to paint it) is change in ir to become invisible you have to hide from the sensor. wear thick clothes and hood and see if it helps

Most everyday motion sensors you'll see around are going to be IR or maybe Microwave (possibly with IR as well as this covers movement in 2 ways). Any movement really is going to set it off. Even if you manage to spray from an angle where it can detect you the spray will most likely set it off. I used to install these things and I've had enough 4am call outs to know that even a slight draught or cobweb can trigger these things!! Cutting the power will almost always result in the battery backup kicking in and all devices connected to alarm systems these days are tamper proof so no opening to cut wires.

I think if you painted a motion sensor, the sensor would register that as motion.