Reference for Pesachim 60:8

א"ל חזינא להו דמידייתי אלמא בלעי ואסירי והתורה העידה על כלי חרס שאינו יוצא מידי דופיו לעולם

About green ones there is no problem, as they are certainly forbidden;<span class="x" onmousemove="('comment',' These were made from an earth containing alum crystals and absorbed freely.');">¹²</span> the question is, how about black ones and white ones? Again, if they have splits there is no question, as they are certainly forbidden;<span class="x" onmousemove="('comment',' The splits permitting them to absorb.');">¹³</span>

Jastrow