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  • heating fatty acids

    Posted by David08848 on July 18, 2016 at 1:42 am

    I found out the hard way that using a microwave to melt fatty acids in a glass measuring cup wasn’t the best of ideas :/ …  Does anyone have any suggestions for some sort of double-boiler (restaurant style would be fine!) that would be good to melt a few quarts of fatty acids?  (I actually own a large oil melter made for soapmaking that I’ve never used but I haven’t reached the capacity to need it yet!)  Something that would easily pour into a small container would work well.  Any suggestions?

    aperson replied 6 years ago 5 Members · 14 Replies
  • 14 Replies
  • Bobzchemist

    July 18, 2016 at 2:15 pm

    My setup here, crude though it may be, works well for when I have to melt fatty acids.

    1.  Induction hotplate 
    2.  Stockpot Set
    3.  Glass Beakers
    4.  Boiling chips
    5.  Saran Wrap
    6.  Beaker Tongs

    Smaller amounts are melted by using the largest stockpot filled with a small amount of water plus boiling chips, and melting the fatty acid in one of the beakers. Larger amounts can be melted by using 2 of the stockpots, putting some water in the larger one, and the fatty acid in the smaller one. Seal the gap between the pots with plastic wrap. (Be careful venting!)

    The water acts as a built-in temperature limit, so it’s safe to leave the setup alone for a while. Only use a stockpot directly on the hotplate if you can be there to constantly monitor and stir the fatty acids  while they’re melting, or they WILL burn/turn brown while you’re not looking.

  • David08848

    July 19, 2016 at 1:00 pm

    Thanks for putting together your reply with the links to everything!  Greatly appreciated!  You posted some ideas I hadn’t thought of and I never head about the boiling chips or thought of the beaker tongs!  My restaurant supply place might have some similar things or I can order some of these online!  Thanks again for all of your suggestions and for taking the time to reply!

  • Bobzchemist

    July 19, 2016 at 2:27 pm

    Boiling chips are a quick and dirty alternative to putting your beakers on a rack to keep them off the bottom of your improvised water bath. Restaurant places won’t have them, and probably will never have heard of them - they’re an old lab trick. Since they are microporous, they break up the bubbles of steam coming up from the boiling water, which can otherwise disturb the water enough to splash dangerously, especially when there are two flat surfaces close together and the system is being heated from the bottom. 

    If the water temperature can be controlled enough that it’s not boiling, they’re not needed. For example, if you’re using a lab water bath, they’re not needed, or if you use a double boiler, or a pressure cooker that has a bottle support, or also if you use beaker clamps and stands to hold  your beakers. But…all of that stuff is expensive or bulky, so if you have limited space, or limited funds, you learn to improvise.

    Leather welding gloves work about as well as beaker tongs to get a beaker out of boiling water, but they’re more of a pain in the butt to take on and off.

  • David08848

    July 20, 2016 at 2:42 am

    Using restaurant stuff has been my way of improvising and has worked well for me so I understand your “inventiveness”!  I have a good quality restaurant hot plate which has worked well for years and many large stainless steel pots of all shapes and sizes but have to keep these batches fairly small for them to work.  I need glass to see through to determine the “homogenization” of this product but am concerned with heating up something glass and if I were to heat the fatty acids up in a double boiler I would also have to heat up the glass container I would process the batches in so that the fatty acids don’t solidify on contact with the cooler glass!  So, if I used a glass container of some sort and heated the batch in a stainless steel bottom of a double boiler it might work.  It may also work to use stainless steel within stainless steel but I haven’t tried that yet.  Either a stainless steel pitcher with a spout or one that is glass but sturdy enough to use in and out of the double boiler and will hold up to the heat and the mixing and pouring… nothing is easy, is it!

  • belassi

    July 20, 2016 at 4:32 am


  • David08848

    July 21, 2016 at 3:00 am

    Belassi,  I took your hint and ordered 3 Two Quart Pyrex Measuring bowls from WalMart!  (rolls eyes) They should be in the store on Friday for pickup!  I checked out the bowls I had and they were Anchor Hocking but this is what happened to them!  What is the difference between them and Pyrex?

  • cherri

    July 21, 2016 at 9:56 pm

    OH WOW.. I have used microwaves before in my lab but never seen that before.. the best way is to use a water bath. ..get a big pot and try to melt your oil phase- like how you melt your chocolate at home…
    I was never ever allowed to heat my batch using microwave… for oil phase- you will not have any water loss but esp for water phase it is not recommended. I think your microwave has less capacity or your beaker is just too weak? I understand how you want to create something at home but try making a small batch first and then scale up. You don’t want to waste your raws.. they are $$

  • belassi

    July 21, 2016 at 11:16 pm

    Well, I really had in mind Pyrex beakers. If you heat in the microwave you can only heat water based or mixed phases, not lipids alone.

  • David08848

    July 22, 2016 at 12:57 am

    I learned about microwaves in Home Economics in High School in 1973 when they were new and just out on the market.  Exciting the water molecules was what we were taught…43 years later you’d think I would remember that?  I use large restaurant size double-boilers for regular soap making in my 800 Sq. ft workroom for my business and I guess I was just looking to make these test batches quickly and eventually the fatty acids did melt but because the glass was heating up which I observed while taking temperatures of the batches.  As I said, the glass did melt the fatty acids but if you don’t continuously stir then the heat builds up and breaks the glass… This was a small batch and my particular formula seems to be only able to work in small batches.  I will set up a double-boiler and try using the new Pyrex 2 quart measuring cups I picked up today at WalMart.  I have the little metal “stand” that sits in the pot upon which I can put the measuring cup and a hand-held thermometer to check on temps during the procedure.  Even if I decide to heat up a larger amount of the oil phase enough for several batches in a stainless steel pot then I can then pour it into these Pyrex measuring cups which I will preheat to match the oil phase temps and go from there!  I posted the pic to make sure no-one else has a “duh” moment like I did!  Thanks!

  • belassi

    July 22, 2016 at 1:35 am

    I generally use a 1KW hotplate with temperature control, and a 4Kg stainless steel bowl, with frequent stirring, if I am melting things like glyceryl stearate and cetyl alcohol and shea butter and so on. 

  • David08848

    July 22, 2016 at 8:07 pm

    I think this worked out much better…for the moment!  The measuring cup is sitting on a special stand inside the stainless steel pot.  I had the hand-held thermometer nearby and kept an eye on it. It never got much above 160F and it worked well to process the batch at the temperature I needed and was fairly easy to pour.  Next time I’ll use the new Pyrex measuring cup!

  • aperson

    May 3, 2018 at 9:51 pm

    Just an FYI, for lab equipment/heating equipment, you are looking for borosilicate glass.

    in the 1950’s pyrex was the brand name for a borosilicate glass of cookware; about 15 years back, Dupont sold the retail rights to a chinese company, that flooded the retail market with cheap tempered glass under the Pyrex brand.

    Hence, no shock resistance to temperature changes, as the glass is not borosilicate glass, but rather, tempered glass.

    I believe if you buy “Pyrex” labware, it is still, borosilicate glass.

    You always, want to make sure, you are buying borosilicate glass.  NEVER, buy tempered glass.  Particularly important for the “home” cosmetics (or cooking!) ;)

    (thats the reason why I reopened this old discussion).

    the correct way to break tempered glass cleanly, is to fill a bottle with oil, and microwave it - the heating of the oil actually introduces a stress at the surface, which allows you to make a clean break (used to convert wine bottles into “beakers”).

  • David08848

    May 4, 2018 at 8:44 pm

    I checked out the glass in the last photo and it is made by Anchor Hocking.  Here is a link to their website which explains the change from “borosilicate glass to tempered soda-lime-silicate glass.”


    Interesting!  They say that this is better then he borosilicate glass!

    I usually use metal pots for everything but in the case of those smaller formulas and test batches that was what I opted for back then!


  • aperson

    May 5, 2018 at 5:17 am


    Its crap. 

    If you had pyrex (real borosilicate), you could thermo cycle it all day long; the tempered glass is guaranteed to shatter under similar circumstance.   Their marketing spin (its twice as strong) is a load of garbage (akin to saying this metal is twice as hard, and therefore won’t crack when you hit it) ;)

    This is marketing fluff trying to explain away what really happened ;)

    Thats why all the labware, stayed the same.

    But all the “consumer” grade stuff, disappeared.

    Thanks for the update, I had no idea this was an “industry-wide” event.   I figured it was a Chinese company trying to capitalize on a brand while pumping out cheap crap.  Not uncommon.

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