Some are concerned that the ink stamps, when boiled, will permeate the pot, and the allegedly chametz part of the ink will make the food Chametz.
Is this a scam?
The international beis din lohoroh notes:
The Shulchan Aruch (442:10) writes that there is no problem in using ink made from chametz, and the Mishnah Berurah (44) explains that the ink is inedible and that there is therefore no problem in using it.
The Mishnah Berurah writes that one must not intentionally eat the ink, but eggs that are stamped will not be considered “intentionally eating ink” even if they are cooked with the ink (see also Shulchan Aruch HaRav 442:34).
The London Beth Din notes:
The ink used to print on eggs is made from two components, a colouring agent and the solvent. The colouring agent is purely synthetic and does not present a problem for Passover.
The solvents most commonly employed are isopropanol, ethanol or a combination of both. The solvent is of such nature, that within a fraction of a second after applying the stamp, it completely evaporates. A moist stamp would lead to unwanted smudges.
It is therefore very safe to assume, that not a trace of solvent remains within a short time of application to the egg. To sum up:
It is not certain if ethanol is used in stamping eggs. Even if ethanol is used, it is not certain that it is wheat derived.
Even if wheat derived ethanol was used, none of it remains after the ink has dried and it no longer constitutes part of the ink.
The OU have paskened:
Q. Is there a problem to use eggs that have a stamp on them on Pesach?
A. One can use eggs with a stamp on them on Pesach without concern.
And yet, we hear about people looking for unstamped eggs, or in Israel, eggs made with KLP ink and a Mashgiach watching each stamp occur, thereby raising the price. Why? Is this an example of a Shtus Chumra?