firm up
US /fɜːrm ʌp/
UK /fɜːrm ʌp/

1.
2.
endurecer, firmar
to make something physically stronger or more solid
:
•
The concrete needs time to firm up before we can build on it.
O concreto precisa de tempo para endurecer antes que possamos construir sobre ele.
•
The jelly will firm up in the refrigerator.
A gelatina vai firmar na geladeira.