Pumice is a very light porous volcanic scoria, usually gray in color. It consistsof pores the size of capillaries that are organized in parallel configuration, giving it a fibrous structure. It is produced by the escape of water vapor from liquid or plastic lava.
Abrasives are evaluated on the basis of three factors- hardness, particle size and shape- and should be chosen according to desired performance, Nakahara et al. have developed an apparatus and method for evaluating these factors. Scrubs made with large, hard and irregularly Shaped abrasives will give a rough feel on skin and may cause irritaion and sometimes damage. In contrast, softer or powder-like abrasives do not give enough massaging effect for de-stressing claims. The most appropriate range of hardness is from 0.5 to 7 (hardness scale from 0 to 10is hardest and 10 is softest). The most appropriate shape is spherical, and the best range of size is from 40 -80 Mesh (180 to 420 microns).Special attention should be paid when using natural shells or seed abrasires became they are susceptible to bacterial contamination. The safest way to prevent contamination is to radiate these raw materials before use in manufacture.
Nonaqueous Formulary
Salt and Sugar Scrubs have recenty become Very popular for body,hand and foot applications. These
products Were developed to meet the Consumer trend of cleansing, treating and rejuvenoting skin all at the Same time. Because salt and sugar are Water-Soluble, their abrasive properties can Only be utilized in nonaqueous formulations. Listed in Table 2 are oils (including natural ester oils, mineral oil, and/or synthetic oils),glycols And silicone fluids. These Are the most COMMON liquids used in the continuous phase of Nonaqueous formations. the salt 08 sugar abrasives can either be immersed or Suspended in the Continuous phase.
Dead Sea salts, Sea Salts, Magnesium sulfate and Sodium chloride are salts are commonly used in this type of formulaSea salts, especially Dead Sea salts, contain A substantial amount of essetial Minerals.The Composition of Dead sea Salts is 31%to 35% Magnesium chloride, 24% to 26% potassium chloride, 0.1 % to 0.5% calcium chloride, 4.0 % to 6.0% sodium chloride and 26% to 30 % of crystallizing water. It has been experimentally and clinically confirmed that Dead Sea salts are effective in the treatment of osteoarthritis,rheumatic discomfort and psoriasis
The size and shape of salts are critical for product performance. The most preferred sizes range from 20-80 Mesh (180 -840 microns). Facial scrubs normally employ finer particles, while body Scrubs hare medium range particles are preferable for less skin irritation and improved feel.
When the abrasive properties of sugar and salt are compared, sugar is found to have certain advantages: Sugar is Softer and Can be made with a variety colors. on the other hand, Sugar is slightly more expensive than salt and contains no minerals for treatment functions. Therefore, the sugar scrubs are not as popular as salt scrubs
Oil- based scrubs: Oils include natural ester oils, Mineral oil and synthetic oil. Some of the natural oils included are shown in Table3. Most of those oils are triglycerides,which deliver good skin feel, moisturization and skin protection.
One problem with natural oils is their tendency to become rancid. AntiOxidizing agents such as tocopherol (vitamin E),BHT Cbutylated hydroxytoluene) or benzotriazolyldodecyl p-cresol are necessary to prevent rancidity. In addition, winterized natural oils are preferred to prevent temperature-related redimentation.
In Oil scrub formulas that carry salt/sugar abrasives, the total amount of oil is 25% to 40%, with corresponding salt/sugar levels of 60% to 75%. the Specific gravity of these particles is higher than oit; thus, they will sink to the bottom of the container when immersed in oil. When this Occurs, the overall product will present with two distinct phases.
There are some limitations When employing natural oils in salt and sugar scrubs. Changing the color of the oil phase is difficult because most natural oils have a yellow or green- yellow hue. In addition, natural oils do not spread easily across surfaces. Therefore the spreadability of natural oils comes into play and is normally represented in terms of viscosity. Light natural oils (low Viscosity)are preferred to heavy natural oils (high viscosity) because they are easier to spread across the skin surface and do not leave a heavy feel. The preferred viscosity range of oil or oil blends is 50 -200 cps. It is the unfor ternate Case, however, that natural oils (except sunflower oil and Safflower oil) Show moderate comedogenicity.
Mineral oil, isoparaffin or synthetic esters (oils)can also be used in scrub formulations. They are usually colorless and odorless and, as such, are readily colored and fragranced to meet marketing requirements.They are also easy to spread and are perceived to be less ''heavy'' on skin. Viscosities below 300 cps are preferred in better performing products. Formula ratios of oil phase to salt/sugar phase for this base type are the Same as with natural oil formulations.
It is worth mentioning that mineral oils are colorless, clear and odorless liquids. They are excellent cosmetic emollients because they are inert and do not penetrate into the skin. Mineral oils have superb skin compatibility and show little or no comedogenic effects.
There are many synthetic esters ( oils) that Can be used in scrubs. Included are: isopropyl esters, ethylhexyl esters, oleic acid esters, caprylic/Capric acid esters,n-butyl stearate,isocetyl Stearates,octyldodecanol,diisopropyl adipate and pentaerythritol tetraisostearate. The price of synthetic oils ranges widely, depending on the chemistry involved in making these oils. Generally however, they cost more than natural or mineral oils.
Suspended oil scrubs:It is somewhat inconvenient to use dual- phase salt/sugar and oil mixtures, since salt/sugar particles settle to the bottom of the container. It then takes time and effort to mix two phase into d degree of homogeneity. To simplify the application process, these abrasives are suspended in the mixture permanently. In suspended formulas, salt/sugar is blended in the oil phase and will not sink to the bottom of the container.
Several methods are used to achieve suspension of salt/Sugar abrasives in the oil phase. In the following example, oils are gelled with thickening agents that impart yield value to the solution. It is the yield value that allows particles to remain in suspension. Fumed silica is one of the agents for gelling the oil phase. It should be noted that fumed silica is very light and dusty, and special protective measures should be taken by compounders. The use of ethylene copolymers is another methods form gets that break easily under shear stress, yet recover viscosity and yield quickly over time, which is to say they have thixotropic properties. As such they are considered a desirable medium for supporting and suspending particles in scrub formulations.The amount of fumed silica or ethylene copolymers varies according to oil type and the desired consistency of the final product.
Other oil thickening agents are quaternium-18 bentonites or stearalkonium bentonites, trihydroxystearin, and Rhns uerniciflua peel wax .These gelling agents also impart yield to the continuous phase and thus will Suspend salts or sugar .
Certain pre-made gels are also suitable for this application. One company offers several pre-made gels composed of mineral oil, ethylene/propylene/stylene copolymer and butylene/ethylene/ styrene copolymer Another Company's line has more than ten different pre-made gels that are oils thickened by bentonite derivatives.
consistency will vary with the amount of salt or sugar added to the formulation. The consistency can further be modified by incorporating surfactants into the system, which can improve both the viscosity, foaming or non foaming, and skin after-feel.
The ratio of oil to salt/sugar is more flexible in suspended oil scrubs than in the previously mentioned nonaqueous systems. The percentage of oil can range from 30 % to 60% and salts / sugar can range from 40 % to 70 %. In summary, colorless oils Can be easily colored to obtain different appearances,and the performance Can be adjusted using surfactants.
Special attention should be paid to the temperature dependency of viscosity and yield. For suspending salts or sugar, the viscosity and yield of oil phases should be stable in the temperature range of- 20°C to 50°C. Different oil thickeners have different temperatare dependency of viscosity and yield. Carefully evolution is needed to safe-guard the stable products.
Glycol- based Scrubs: Glycols and other humectants can be used as carriers in salt scrubs. Included in this category are glycerin, propylene glycol, butdene glycol, pentylene glycol, hexylene glycol and polyethylene glycols of various chain lengths. Sugar is somewhat soluble in glycols and is not appropriate for this type of formula.
Glycol-based scrubs have a self-heating function when they are rinsed with water, which provides an interesting rejuvenating skin as these products are used.
Glycol scrubs have two important benefits:they are colorless and are not susceptible to chemical change. Thus, chemists can easily make a variety of colorful products and need not worry about problems such as rancidity.
Both separated and suspended scrub types are achievable with glycols. The ratio employed in the salt / Sugar and oil fromulary also holds for glycol formulas:25%to 35%glycols and 65% to 75% salt phase. The disadvantage for this type of scrub is lack of good skin after-feel. Su