I actually was on a tour of the Postive factory a few years agi with Rabbi Wickler of Kashrus Magazine. We were also treated to classes on bug checking and infestations.
After that, it is a no-brainer. I ONLY use Postiv (or a few other rare Greenhouse products.) I don’t use those other brands at all, based on what I learned.
Without saying any LH about what is wrong with other products, I can tell you that Postive has some major advantages:
– They are grown in a sealed greenhouse completely isolated from the ground soil, so bugs cannot get in. Even in the greenhouse, they spot check the produce while it is still growing.
– They check every batch once it arrives at the factory BEFORE washing it
– They wash it in a process that is VASTLY superior to most other companies for certain reasons that they might not want divulged
– They check EVERY SINGLE ounce of product before bagging it. Yes, that is correct – they don’t just spot check! They have a method wherby they check everything.
There are some bugs (mites) that are so small that once they infest lettuce, they are difficult to spot even using a lightbox. Non-greenhouse lettuce just cannot be guaranteed clean, even with all of the ‘washing’ and spot checks that other companies do.