By Dr. Mateen Khan (Trenton, New Jersey)

Approved by Mufti Husain Ahmad Madani 

From the standpoint of the shari’ah, when something changes in its essence (istihālah), then the ruling (hukm) associated with it also changes. 

A similar ruling applies for soap, which is made by mixing a fat or oil, from animals or plants, with a base like lye or caustic soda. The fuqahā’ say the animal fat or oil may be najas and haram, but the soap made from it is tāhir and halal. The ancient Arabs typically used vegetable oil, lye, and a fragrance to make their soap. This process of making a soap remains unchanged until this day.

Let’s look at Dart brand foam cups, made from a plastic called polystyrene. Dart uses a process called steam chest molding to make its styrofoam cups. The polystyrene pellets are heated and placed into molds, allowing the pellets to expand and fuse while taking shape. A second process called extrusion/thermoforming is used to make plates and other dinnerware.

Dart uses a lubricant in the extrusion process of their polystyrene pellets that contains zinc stearate. This ingredient allows the polystyrene foam to separate from the molds. Zinc stearate, a white powder, is made by reacting sodium stearate with zinc oxide or zinc sulfate. Sodium stearate is a soap found in a multitude of household items, including deodorant and even some foods as additives and flavoring. It’s made by reacting the fat/oil byproduct of animal leftovers, called tallow, with lye in a process identical to making soap.

The standpoint of the shari’ah mentioned earlier—that when something changes in its essence (istihālah), then the ruling (hukm) associated with it also changes—applies to the zinc stearate in Dart styrofoam cups too. The zinc stearate is derived from sodium stearate, which is formed from tallow and lye. The initial tallow may be najas and haram, but the sodium stearate is tāhir and halal because the tallow underwent a process entailing istihālah. Hence, zinc stearate does not make Dart brand products najas.