I was recently present for the kashering of a cheese plant. The cheese is first heated in a large vat (kli rishon) and then transported via strainers into an unjacketed mixer vat. Since this second vat has no independent source of heat, the product that is poured into the vat is considered to be an irui kli rishon of cham litoch tzonen. However, since the consistency of the cheese at this stage is that of a semi solid, it is likely that we should view this cheese as a davar gush. How do we kasher the mixer that had an irui of a hot davar gush, and the pipes that continue on from there?
As we have written in the last issue, the Mishnah Berura 451:114 brings the Mahari Viel 193 who says that kashering from a davar gush requires the use of an even miluban (a super heated stone). Unfortunately, I had left my even miluban at home, and we were faced with the real world issue, of what should a Mashgiach do to accomplish the level of kashering of an even miluban. The way we dealt with the issue was to pump the boiling water from the heated vat into the mixer and insert a steam hose into the mixer. This accomplished that the hot water came back to a boil in the mixer. Our steam hose has taken the place of the even miluban.
The Pri Migadim (O.C. 253:32) and the Pischei Teshuva (Y.D. 94:7) say that a davar gush that is immersed in a liquid in a kli sheini will also attain the status of a kli sheini. Even if it is subsequently removed from the liquid, it will still retain the status of a kli sheini.
In our case, as the cheese gets poured from the strainers into the mixer, initially we have irui davar gush. However, as the mixer fills with cheese, more and more liquid accumulates. Eventually, the davar gush (cheese) is floating in a pool of liquid. At that point the contents of the mixer are considered to have the status of a kli sheini, and any subsequent pumping of this cheese will only be considered an irui kli sheini. We can therefore kasher the rest of the pipes by simply draining the hot water through the pipes.
In summary to kasher from a davar gush
1. A steam hose can be used instead of a heated stone.
2. Once a daver gush is immersed in a liquid it attains the status of a kli sheini.