Pampers make diapers which have a wetness indicator. Initially it is a yellow stripe when dry; when wet it turns blue. I am wondering whether this would be considered tzoveha. ...
A novelty cup, see for example here, appears black when cold. When hot liquid is poured into it, the black changes to white and the previously concealed writing (underneath, so to speak) becomes ...
In the question Pregancy Test on Shabbos a notion was raised in an answer that the chemical reaction is a problem due to tzovaya. So what are the boundaries of this, in terms of chemical reactions ...
Why is making fruit punch on Shabbos not a problem of coloring?
It is going to sound strange but here is the question In the toilet there are these blue things that clean your bathroom with every flush by adding bleach hence it colors the water blue every time you ...