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  • Need Your Expert Opinion: Cooking with PVP / Aluminum issue

    Posted by Clark on July 20, 2016 at 5:34 am

    Hey Chemists,

    I brew hair products in about 2000g batches. Was doing so in a “presto pot” (basically a controlled heating teflon coated crock pot) for a few batches.

    But then…

    I noticed black specks contaminating one batch (there goes $300 worth of product…) and haven’t used it since. I suspect this could be the teflon layer chipping off into my product? Possible reaction with PVP?

    My ingredients are: Water,  Ceteareth-25, Glycerin, PEF-7 Glyceryl Cocoate, Propylene Glycol, PEG-40 Hydrogenated Castor Oil, Polysorbate-20, Dimethicone, PEG-8 Beeswax, PVP, Fragrance, Color

    I would appreciate your input:

    1. What caused the teflon to come off?
    2. What is your recommended gear for brewing 2000g batches (with separate water / oil phases) to avoid this same issue. Something within $100-200 price point as spending $2000 is not an option at this point.
    3. I assume glass could solve this issue. Any links to popular products used for larger chemistry cooks?

    Thanks!

    -Clark

    Bobzchemist replied 8 years, 4 months ago 3 Members · 2 Replies
  • 2 Replies
  • Bill_Toge

    Member
    July 20, 2016 at 9:19 am

    I recall someone on here had a similar problem not so long ago, with black bits appearing in their product after they’d filled it into in aluminium tins

    aluminium is a very reactive metal, and if part of the internal lacquer/coating is thin, it can leach into the product - I think this is what’s happened here

    in my view using a stainless steel (i.e. inert) vessel, as used in industrial production, is the simplest solution

  • Bobzchemist

    Member
    July 20, 2016 at 2:13 pm

    PVP won’t react. All teflon coatings are not the same. Cheaply-made teflon coated cookware can easily flake off the teflon. 

    Glass 3 kilo/3,000ml beakers are cheaper than stainless steel ones…but then they break, so…you choose when to spend the money. 

    You can use the stainless steel stockpots that are usually used for cooking, instead of beakers, especially if you passivate them when new before you use them (and anytime after you clean them with something abrasive).

    Clean/degrease the pot. Use a 10% Aq. Citric Acid solution at 150 - 200F to soak the pot in, or fill the pot with the solution and heat it. Let the reaction run for at least 30 minutes. Rinse very well.

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