Rules Involving the Use of Tape

Are we allowed to use black electrical tape to block unwanted background inputs from being sensed by the optical sensor?

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Any question that asks “are we allowed” or “is it legal” must be answered by consulting the game manual. In this case, the rules for tape are covered in R-11 of the game manual.

If you have a question after reading R11 of the game manual, feel free to ask a follow-up question on the forum.

You might consider making a legal cover using opaque plastic, for example black abs available from


Ah yes, it says a small amount of tape is allowed to tape wires together, motors (for numbering), the backs of license plates, unwanted leaks, for securing the VEXnet key to the controller, and any other application that would be considered a non-functional decoration. So I guess that’s a no. Thanks for your time.


Now, I believe you can use other colored materials for the purposes of balancing the light sensor.

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It would be better if you said “I know you can…” and cite rules or Q&A for others to learn from you wisdom.

The Game Manual and Official Q&A are your friend for stating facts on the forum.

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I wasn’t providing an answer, rather leading the OP towards their possible solution. But will do in the future.

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Depending on the specific application, “blocking unwanted background inputs” with tape might be OK under <R8a>:

<R8> Certain non-VEX components are allowed. Robots are allowed the following additional “non- VEX” components:

a. Any material strictly used as a color filter or a color marker for a VEX Light Sensor.


Interesting interpretation of “filter” in this application of tape to achieve the stated purpose of the problem. My knee-jerk reaction would be to state that filter means to allow signal through - but thinking it through, “blocking unwanted background inputs” (signal/noise), truly appears legit use of filter in engineering and in this application.

Well done @holbrook and @NicolBolas - this is the forum discussion I truly enjoy!


Wouldn’t that apply ONLY to the Vex Light Sensor (as opposed to the Optical Sensor that the OP indicated)?

Secondary thought - @Capten, couldn’t you use the Vex adhesive foam or antislip mat or even just black polycarbonate sheets?


Hmm, interesting point - I had interpreted “light sensor” as a generic term that would describe any of the several VEX sensors that “sense light”. But one of those sensors is literally called the “VEX Light Sensor”, and “Light Sensor” is capitalized in the rule.

Might be worth a Q&A…


Thank you! This is pretty interesting. Strictly speaking, it doesn’t specify what it’s filtering so it could “filter” any wavelength of light and still read as opaque to the sensor. I agree with @holbrook that this needs a q&a.

Attempting to state facts on the forum is your enemy if you dont want to cite sources

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Yes that is what we did, we used a multi-layered white antislip mat to provide as our background for the sensor. Thank you everyone for all your help.


Well, that was quick!

Yes, the Line Tracker and V5 Optical Sensor would be covered by R8a.