Scaling up products from a home batch to larger-scale production often presents many surprising challenges. It is not simply a matter of multiplication to get the same end product—the very nature of large scale production changes heating and cooling times, temperatures, ratios, and more. Instead of receiving an unpleasant shock between prototype and production phases, let’s explore what is likely to be an issue and how to manage it. Here’s a rough overview with some thoughts to keep in mind, and we’ll elaborate more in the future.
Something Almost Always Must Change
Formula scale-up is not as simple as multiplying. I liken cosmetic manufacturing to baking, though I have spoken to some folks who have gone from baking and/or food science into cosmetic formulations and they say cosmetics are far less predictable. The analogy I use is that in a home kitchen when one is baking a cake. They can double or triple a recipe and still use the same ingredients, measuring tools, and baking time. But when a yield increases from that cake needing to feed 8 people to now 800 people, things change.
- The usual process of scaling up starts with a prototype in the lab, often just a pound or so, then moving up to a “pilot batch” of perhaps 100 pounds. This might then culminate in a final production batch of 1,000 pounds. Along the way, each step offers something useful.
- Ingredients may not behave in the same way, so they may need to be adjusted or changed to achieve the desired result. For us in cosmetics, it’s electrolytes, polysaccharides and numerous others that can’t simply be evenly multiplied when scaling up.
- One of the biggest factors in selecting ingredients for a formula is knowing how they will scale. We try to ensure is to not use an ingredient whose stability may not meet the needs of a larger batch and process. This situation is one of trial and error as well. Two different preservatives come to mind where we have had to waste thousands of pounds because their use was not scalable in the same manner we had used in the smaller batch. Trial and error form the base of scale-up.
General Issues to Consider
Reviewing the above considerations, you can see how the finished product may have a different texture or viscosity as a result of scale-up. So products often need to be “reworked” until the production batch matches the approved prototype.
Here are some other examples of quite common issues that arise.
- 1) The length of “cooking” time will change and there is almost no way to determine how to translate the cooldown of 1 pound in the lab, to a 200 pound pilot batch, to a 2,000 pound production batch.
- 2) Another part of production that is impacted by scale-up is the ingredient delivery method one chooses to use. For example, in a laboratory setting, incorporating a chunk of Shea Butter into the recipe is easy—just cut it into pieces and transfer it into the mixer. However, when one is handling a 50-pound block of Shea butter, the method is vastly different.
- 3) Will the setup of your production area affect the product? This might include sizes and types of pipes and pumps that product will pass through.
- 4) Can ingredients still be manually added, or are their characteristics such that they need to be slowly sprinkled over the surface of a now much wider-diameter tank? Maybe they need to be mixed at a very slow rate, or all of a sudden you have to turn up the RPMs greatly.
- 5) Do you need to prepare ingredients in some way before they put them into the mixer or another part of the process? Is this understood each time before scale up?
Mixing Considerations
Mixing is a complicated science. Many types and sizes of mixers are available to meet specific needs of viscosity, volume, and material. Determining which type such as high shear, static, milling, baffled or not, etc., and also the size of the mixer to buy, is complicated. A wrong decision can be costly from a quality, production, and replacement cost standpoint. Questions that not only need to be answered BEFORE scaling up but also might have been answered incorrectly and then need to be looked at again are:
1) What is the desired viscosity of the product throughout the mixing cycle?
2) What is the desired pH between each phase?
3) What are the color, odor, and rheology (the flow of a liquid) between at the highest temp and then at the lowest?
4) What type of mixing does one need to accomplish? For instance, incorporating Jojoba wax beads into a cream base requires folding, whereas ensuring powdered ingredients are mixed incorrectly we would shear-mix to break up clumps.
5) Will one need to reevaluate the order of additions? A thick mixture, when scaled up, can require much more powerful equipment to mix it at its thickest point, but perhaps changing the order of addition will prevent the product from becoming as thick.
6) Can one piece of equipment be used to scale-up multiple products? One will need to evaluate the products’ ingredients, viscosities, and solids content to determine this.
7) How much will the diameter of the tank and mixing blade affect the mix and temperature? Smaller blades in larger tanks have a harder time of thoroughly mixing all the product, much of which can get stuck to the side of the tank and never properly integrate without a person routinely scraping the sides. So not only is mixing a greater challenge in larger tanks, but the temperature can be noticeably different on the sides of the tank compared with the center.
Temperature and Scale Up
Now if everything I mentioned isn’t bad enough, there’s another big problem here: the larger surface area and greater volume of production versus lab or pilot batches. The area and volume will greatly impact heat transfer for both heating and cooling. When heating larger quantities, it is tempting to increase the temperature to increase the heat transfer to the product. But for some heat-sensitive ingredients, which many in the cosmetic world are, the higher temperatures can cause products to burn or simply to oxidize too fast and have an odd color change; 2 problems that affect the quality of the product and the cleanup. So with this we need to ask:
1) How will the times and temperatures of heating and cooling be impacted?
2) How will the heat treatment impact the scent and color of the product?
3) Will the heat treatment affect the preservative negatively and if so, will we have to wait 5 days for our bacterial assay to simply fail and we have to start all over again?
4) Will heating and/or slow cooling affect the raw material selection and order of additions?
Pilot testing can help determine the most efficient process for these costly process and utility changes in methodology. The real way to avoid major problems before a production run is taking the time to run pilot batches and tweak formulas and methodologies until it’s as close as possible to being ‘nailed down’. As you can see, more time and energy than you might desire is involved in scale-up. Your account executive understands this and is here to help!
We’d love to hear what your own issues with scale-up have been and how you tackle them.
