6
votes
1answer
105 views

Is it permitted to use a thermochromic cup on Shabbos?

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 ...
2
votes
1answer
109 views

Making Fruit Punch on Shabbos

Why is making fruit punch on Shabbos not a problem of coloring?
9
votes
1answer
129 views

Tzoveah on Shabbos

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 ...