Tuesday, May 15, 2012

The importance of temperature - an example

I know this seems like a really boring topic, but it's one that we neglect at our peril. Temperature is such an important thing for our products, yet I see people arguing against heating and holding all the time. It is vital that we bring our lotion ingredients to the correct temperature to allow them to create a stable emulsifier. It is vital we bring water and other water soluble ingredients to the right temperature to make sure we aren't allowing any beasties into our products! And it's vital that we heat ingredients like shea butter to the right temperature to avoid graininess (in some products).

I was just at a supplier's web site and they advised against heating shea butter because it would ruin the goodness in it. This is simply not true. Shea butter can handle much higher temperatures than our heat and hold phase at 70˚C or 158˚F. Another suggestion on this site was that grainy shea butter should be tolerated - you shouldn't have to temper the product. Again this is completely wrong. I wouldn't tolerate a grainy product, and I'm sure you wouldn't either. It doesn't matter than a grainy butter is just as good as a non-grainy butter, it just feels wrong on my skin! 

I thought this would be an interesting demonstration of how much a small change in temperature can affect our products. My workshop is unheated and it's generally the same temperature as the outside world. For the last few weeks, we've been hovering around 14˚C. This weekend, we shot up to 23˚C and possibly a bit higher. 

When I made this product, it turned out really pearlized and thick - a little thicker than I thought it should be, truth be told. But I was happy with it and poured it into the storage and pump bottles. My product had cooled properly and was definitely at the ambient temperature in the workshop, but that's a tiny bit lower than what would be considered room temperature, and look at the difference! The product is really a clear, slightly thinner version of the original!

Surfactants have what is called a cloud point - it's like the titer point in oils - the point at which the surfactant starts to solidify. Generally we have to heat the surfactants well to get the solids to incorporate into the product, but in the case of this hand cleanser, it turned out okay. What's interesting is that my workshop was only slightly below room temperature (18˚C to 20˚C) and that difference was enough to alter the product pretty substantially.

Never underestimate the importance of a few degrees. It really can make a huge difference! 

Related posts:
Iron Chemist: LSB (some information on titer points relating to LSB)


melian1 said...

another important thing about temperature is that i've found that if my oil and water phases are more than 8-10 degrees (F) different, the emulsion will have trouble. one more reason that heating and holding are so necessary. the phase temps are then the same.

Nancy Liedel said...

Excellent point that completely explains my failed lotion the other day. I had them too far apart in temperature, because the lotion should have been fine otherwise. I had a higher oil temp and then some separation. I do not agree with those that say, "Shake it."

Separation means toss out. I did and will continue to do so.

I'll mess with soap. Never lotion.

Michelle Squyars said...

When taking temperatures of your oil and water phases, can you use an infrared thermometer? I used one on my last lotion and I got separation (telling me the temperatures were not in synch). Also, if I use a candy thermometer, do I have to have two (one for each phase), or can I clean the thermometer between checking each one?

Susan Barclay-Nichols said...

Hi Michelle! I would use thermometers that you dip into the product rather than an infrared one as I think it's more accurate. And yes, you want to have one for each phase.

Michelle Squyars said...

I made lotion yesterday using two instant read thermometer with great success. And I'm so excited to report that I made my first shampoo this morning. I used your basic recipe, mixing 10% SCI, 5% cocamidopropyl betaine, 3% salt, 1% fragrance and 1% preservative. Thought I would start basic, then make adjustments with future experiments. This is going to be more fun than soaping. Thanks.