Full-scale production: problems and solutions. (Gleams & Notions).

SEVERAL YEARS AGO, my column detailed how to scale up from a laboratory formula to a pilot plant batch (see Happi, February 1991, p. 24). This month, I'll detail various techniques used in full-scale cosmetic production.

Some companies, primarily smaller ones, use production chemicals "as is" from the supplier without changing the tradenames to prevent spying. Other firms use an opaque paint to obliterate the trade name before sending it to the processing area. These companies use code names for all raw ingredients. Some even use code names in their R&D labs. I worked for a company that used my first name as a code for formaldehyde. Unless the new chemist has access to the code sheet, he will be formulating blind and since code names are different in every company, his previous formulating experience will be useless.

Dyestuffs, which are usually in small containers, coded or not, should be weighed by the laboratory in order to obtain a more accurate weighing by using a smaller scale.

Most chemicals are delivered in 55 gallon drums. If the entire drum is not used in one batch, which is often the case, drum trolleys can be used to allow a partially used drum to be stored horizontally at a height suitable for drawing off the contents into a weighing container. Another useful piece of equipment is an electric heating mantle that fits around the drum. This prevents a viscous raw material from becoming more viscous or even solid in cold weather. Use of a heating room is another way to keep liquids pourable.

When very large quantities of a chemical are frequently used, it may be more economical and convenient to buy in bulk and store in tanks. Some suppliers may install their own storage tanks at little or no cost if a long term purchasing agreement is reached, the use of a tank eliminates a large amount of work involved in handling the material and saves a considerable amount of drum storage space.

One of the most important pieces of equipment used in the plant is the mixer. Most cosmetic companies use stainless steel tanks, jacketed with separate access for steam and cooling water. One point which is sometimes overlooked is the necessity for careful design of the tank's outlet valve. In the closed position, the top of the should be flush with the inner surface of the mixing vessel. Some vessels have several inches of pipework below the mixing surface and above the valve which can be filled with raw materials during processing. This can cause a quantity of unmixed product or raw ingredients to come out when the valve is first opened. If the unmixed material is a pigment or a wax, it will not disperse in the now cooled bulk. Another disadvantage of bad valve design is that microbial colonies can grow in inaccessible sites that may cause contamination of the finished product.

The mixing apparatus in the vessel should be versatile. It should contain both high speed mixing and slow speed (paddle type) mixing on the same shaft. The high speed propeller mixing is needed at the beginning of the batch when powders or a gum thickener (such as carbomer) is dispersed or dissolved. When the batch cools and thickens, slow speed mixing is required to eliminate air.

Economical Formulations

When making an emulsion economically, the process should have minimum heating, shearing and overall manufacturing time. This can be done by keeping the oil phase just above its melting point immediately before emulsification. If a wax melts at 70 [degrees] C, it is a waste of time and energy to heat it to 85 [degrees] C. Another way of reducing heating costs is to melt the fats and waxes with a small portion of the oil and then adding the rest of the oil.

The minimum quantity of water (at the same temperature as the oil) should be used to form the emulsion. As soon as sufficient emulsification is achieved, the rest of the room temperature water is added. This will eliminate a major part of the cooling cycle. The cooling cycle is completed by running tap water through the jacket of the mixing tank. This technique applies primarily to oil-in-water emulsions. Other low temperature emulsifications can be accomplished if there are no solid lipophilic ingredients and solid hydophilic materials are readily soluble in water or water soluble solvents.

HARVEY FISHMAN HAS A CONSULTING FIRM AT 34 CHICASAW DRIVE OAKLAND, NJ 07436, [e-mail], SPECIALIZING IN COSMETIC FORMULATIONS AND NEW PRODUCT IDEAS, OFFERING TESTED FINISHED PRODUCTS. HE HAS MORE THAN 30 YEARS OF EXPERIENCE AND HAS BEEN DIRECTOR OF RESEARCH AT BONAT, NESTLE LEMUR AND TURNER HALL. HE WELCOMES DESCRIPTIVE LITERATURE FROM SUPPLIERS AND BENCH CHEMISTS AND OTHERS IN THE FIELD.