Why Weigh Soap and Cosmetic Ingredients?

Have you ever searched the internet for cosmetic formulas? A search for nearly any product turns up more variations than we can try in a year, perhaps more. The question is, of course, are they good? Will they provide the results we hope for? Are they well researched and written?  Although many factors determine a worthwhile formula, an alarming number of them call for measured ingredients, in cups and tablespoons. Why weigh soap and cosmetic ingredients?


What’s wrong with that?

Is it acceptable to measure in cups and tablespoons? Must I own a scale to make good products? This is particularly a dilemma for US makers, who are used to cooking and baking with measuring cups and spoons, rather than by weight. It is only natural for someone new to cosmetics to choose formulas that require utensils similar to what they use in their kitchens. I know. Many of you will point to your first soap formula or your great grandma’s formula calling for a can of lye, the fat from a hog, cups of this and spoons of that and how they made good products.

Yes, you and others may create or created outstanding batches with imprecise tools and methods. It is true that the exact same measuring tools and methods will produce consistent batches because the maker provides the consistency by making the product the same way each time.

What is the problem, then? Read on

  • A “recipe” in cups and spoons does not provide enough precision and consistency. If you get new new measuring cups or share the formula, for instance, the result may not be favorable. To be sure, measuring utensils are approximate. What measures one cup to you might be less or more for someone else, which can throw the product off enough to cause a failed batch, or at least an unsatisfactory batch. To test this theory, measure water to fill a one cup measuring cup and pour that into another one cup measuring cup. If you have several, try them all. You will probably find that the amounts vary. The same is true with measuring spoons.
  • In addition, the measuring cups makers often use are not meant for liquids to begin with, so measuring oil in a one cup measuring cup meant for dry ingredients will not offer the same result as a cup meant for measuring liquid ingredients. If we cheat a bit in cooking, it may not matter, but in cosmetics and soap, it very well may.
  • Consistency and accuracy are important in making repeat batches, especially for sale. The best way to ensure consistency is by weighing ingredients rather than measuring them.
  • This is the 21st century, and best practice, even for hobbyists, is to measure by weight. Scales are plentiful and inexpensive. Get accurate, consistent measurements for any formula and weigh ingredients. When you get a formula from another maker, follow it as directed to get equal results, personal differences notwithstanding.

What Should I do?

Purchase a digital scale. Fortunately, what you need is not terribly expensive. The least expensive run on batteries, but calibrate it often; when batteries begin to lose power, the weight fluctuates, causing inaccurate measurements. If you spring for a scale that comes with an adapter to plug in, even better. Calibrate it on a regular basis still, but deviations due to low batteries are non-existent, and you avoid constantly buying those pesky batteries or the inconvenience of not making a great product when you have the chance because you lack fresh batteries. Calibration weights are very helpful, as well, and recommended.

Look also, for a scale that measures in pounds/ounces and grams. This is especially true for smaller batches, as grams offer more accuracy. If you plan to make large or tiny batches, you will probably need to invest in a second scale or even a third if you produce tiny, medium and large batches. To begin with however, a scale that weighs as small as a gram and as high as ten pounds or so, is suitable for soap and medium batches of lotion and such.

Remember, cups and spoons are acceptable for cooking and baking, but not for soap or cosmetics. When precision is imperative, weighing goes a long way to provide that consistency. Your scale is sure to become your new best friend!

What weighing tips do you suggest? What brand/type scale do you recommend?

Until next time, may your days be filled with bubbles and wax.

Beth Byrne, for Making Soap, Cosmetics & Candles Magazine