Lipsticks

Lipsticks

Lipstick may be defined as dispersion of the colouring matter in a base consisting of a suitable blend of oils, fats and waxes with suitable perfumes and flavors, moulded in form of sticks to impart attractive gloss and colour, when applied on lips

A lipstick, consists of a wedge- or ‘bullet’-shaped stick that is moulded hot and then cooled before being placed into a small plastic cup or godet, which is held in a plastic or metal case.

The godet can be moved up and down inside the case by a screw or push action.

Typically weighing 5-6 g, lipsticks are presented in this specialized type of container, which is cylindrical and specifically designed to aid application whilst protecting the stick

Requirements of Lipstiks

• It should efficiently cover lips with colour and impart a gloss which would last long
• It should not be gritty
• The stick should not dry
• It should be safe and non-irritating
• It should adhere well to the skin of the lips and, during wear, the colour should remain the same and not smear or run
• During application the product must be smooth, but not greasy
• Should not transfer from the lips to other surfaces such as cups (or shirt collars), skin
• The stick should be strong enough so that it does not break when force is applied; for example during application
• However, too rigid a stick will be difficult to apply and would pull at the skin
• The stick should be free of blemishes and airholes or pinholes
• The properties of the stick should remain consistent during its life and it is important that with time the formulation remains consistent and that particles of wax or oil should not form on the surface, a property called ‘sweating‘
• These products are regularly carried around by the user and, as such, can be subjected to a variety of temperatures.
• The stick should not be affected by these changes of temperature and should retain its applications characteristics at all times

Formulation of Lipstiks

To consider the formulation of lipsticks the basic raw materials are conveniently classified as follows:

1. Wax mixture
2. Oil mixture
3. Oil mixture
4. Bromo mixture
5. Colors
6. Preservatives and other additives

Wax and oils:

• Best results are obtained by using a mixture of waxes of different melting points and adjusting the final melting point of the stick by adding a sufficient quantity of a high melting point wax.
• Formulation which contain a high concentration of a single high melting point wax should be avoided.

1. White Beeswax:

• A useful material to bind oils and higher melting point waxes.
• The molten wax shrinks slightly on cooling.
• Higher concentrations give a dull waxy appearance and cause the stick to crumble during use

2. Ozokerite wax:

• Sticks containing more than 10% Ozokerite tend to crumble during application

3. Candelilla wax:

• Gives a smooth and glossy appearance to a lipstick if used at a slightly higher dosage concentration than the proportion of beeswax

4. Paraffin wax:

• Show strong oil adsorption properties

5. Cetyl alcohol:

• Binding agent between polar and non-polar ingredients

6. Lanolin:

• Offer adhesion due to its plasticizing as well as luster

7. Isopropyl lanolate:

• Disperse pigments well and has convenient fusing properties to other ingredients

8. Cetyl lactate & myristyl lactate:

• Has a wax like consistency at room temperature but melts on contact with the skin, giving the product a soft effect

9. Castor oil:

• Is used in nearly all lipstick preparation because of its property as a wetting agent for pigments
• It has a thick consistency which provides stability

10. Paraffin oil:

• Serve as lubricant for application and also adds lustre

Color system

Permitted colors must be used.

• The color is painted to the lips in 2 ways:

1. By staining the skin with staining dyes.

• These are dye stuff in solution capable of penetration the outer surface of the lips e.g. acid eosin, and other halogenated derivatives of fluorescein known as (bromoacids).

Disadvantage:

• Difficulty of uniform dispersion of these dye in the lipstick mass which resulting in shade variation
• So Amine salts of bromo acid dyes, dissolve in a mixture of waxes and oils can be more uniformly dispersed

2. By covering the lips with a colored layer:

• The color is produced by insoluble dyes and pigments, which make the film more opaque
• Both inorganic, organic pigments & metallic lakes are used

Titanium dioxide:

• The most effective white pigment used to obtain pink shades and opaque film on the lips
• Protecting them from the aging effect of the sun

Metallic Lakes:

• Ca, Barium and Aluminum lakes of many D&C color.
• A mix of staining dyes, pigments and Tio2 (Titanium dioxide) is usually used in lip stick preparation

Formula- Lipstick

Carnauba wax                                         10%

Bees wax                                                  15

Lanolin                                                       5

Cetyl alcohol                                             5

Castor oil                                                   65

Industrial Manufacture of Lipsticks

1. The 1st stage of manufacture is the formation of the wax base
2. The oil is heated in the process vessel to 175 – 185˚F (80 – 85˚C)
3. The waxes are melted separately in a hemispherical jacketed vessel (often called a “kettle”) typically fitted with an anchor stirrer/scraper – Part of the oil may be added to the kettle to aid the process

4. The wax phase is added to the oil phase

• High shear mixers should not be used as they introduce air into the product which is difficult to remove and can cause problems later when moulding and flaming the finished bullets

Industrial Manufacture of Lipsticks

5. Pigments are selected for a particular shade by carrying out a series of mixing trials
6. Dry powder pigments are never added into a lipstick as they are very difficult to disperse uniformly. Each pigment is first milled into a paste in some of the castor oil, typically in a ratio of 1:3
7. The pigment should be stirred into the castor oil and then left to stand, preferably for several hours or overnight, and then the whole mixture is passed through a triple roller mill, colloid mill or ball mill to grind the pigments into the castor oil completely
8. After the pigment mass is ground and mixed, it is added to the hot wax mass until a uniform color and consistency is obtained
9. The molten lipstick mass is then run out of the vessel via the tap into the pre-warmed and lubricated moulds which are filled to the top to allow for shrinkage of the mass on cooling
10. The filled moulds are then placed either on a cooling table or into a large fridge/freezer to set
11. When the mass has set completely the mould is removed from the cooling area, the surface lipstick is scraped away and can be recycled
12. The mould is then opened up and the lipstick bullets carefully removed and either transferred straight into the lipstick cases or stored in trays until required for finishing
13. Once filled into the holders, the sticks may be “flamed” to produce a glossy finish to the surface and to remove any imperfections

• Flaming is an intricate procedure if carried out by hand and needs plenty of practice to achieve the required finish without melting the bullet
• The moulded lipstick is passed through a flame whilst being rotated
• On a larger scale the holders can be placed on a conveyor belt and are flamed whilst spinning past in front of a flame or hot-air jet.
• Tip shapes:The three shapes common to early lipsticks – chisel, bullnose and bullet – were added to over the years and now include exotic forms going by names such as sculptured, blunt, gothic, fishtail, teardrop, moondrop, contoured, bullet-wedge, moondrop-wedge and sculptured-teardrop.

Variations in manufacturing procedure

• Split moulding many lipsticks is a time-consuming, wasteful and labour intensive method of manufacture
• It also produces poor-quality sticks in general with many surface imperfections
• Most modern lipsticks are produced on automatic lipstick machines
• One of the most common automatic machines consists of a table of moulds which rotates through various heating and cooling chambers
• The warm moulds are first lubricated by spraying in a small amount of oil, usually a low-viscosity silicone fluid
• They then pass under the filling head where the molten lipstick is injected into them
• As they move round the table they are cooled by refrigerated compartments and finally ejected out of the moulds by a small jet of compressed air straight into the cases
• The full holders are then placed onto a conveyor belt and passed through a tunnel; while spinning they pass in front of jets of hot air which ‘flame’ the surface to give the required glossy finish
• The next stage of the belt then twists down the holder to allow operators to put the caps in place
• The labels are then applied to the base, again automatically, and the completed lipsticks stored until required for dispatch, or shrink sleeved and placed into display cases for the shops

Evaluation of Lipsticks

• Quality control procedures are strict since the product must meet USFDA standards
• Lipstick is a cosmetic which is ingested and because of this there are strict controls on the raw materials and the manufacturing procedures
• Lipstick is mixed and processed in a controlled environment so it will be free of contamination
• Incoming material is tested to ensure that it meets required specifications
• Samples of every batch produced are saved and stored at room temperature for the life of the product (and often beyond that) to maintain a control on the batch
• As noted above, appearance of lipstick as a final product is very important
• For this reason everyone involved in the manufacture becomes an inspector, and non-standard product is either reworked or scrapped
• Final inspection of every tube is performed by the consumer, and if not satisfactory, will be rejected at the retail level
• Since the retailer and manufacturer are often times not the same, quality problems at the consumer level have a major impact on the manufacturer.

In Process evaluation tests

1. Colour matching:

• is done by comparison with a standard shade
• The color matching is also done on the skin

2. Texture

• This test is done to check the presence of solid unwanted particles in the lipstick
• The test is important as regular usage of lipstick with gritty matter can scratch the lips in the long run.

3. Softening point

• The softening point is the temperature at which a material softens
• This test is conducted to check the stability of lipstick at high temperature
• As per the standard requirement, the minimum softening point of lipstick should be 55 °C

4. Melting point

• The determination of melting point is done in order to determine the storage characteristics of the product

5. Breaking point test/ Cantilever test

• This test measure the firmness and bending force of a lipstick
• An important property sought by users is that the product must not bend, crumble, crack or break during application
• Selection of the correct base ingredient quantities, for example waxes of specific melting points, is such to formulate a product with moulded stick resilience, which possesses enough rigidity to withstand firm application to the lips by the user
• This test gives the value of the maximum load a lipstick can withstand before it breaks
• The lipstick is held horizontally in a socket and weight is applied at a measured distance from the edge of the support
• The weight applied is increased gradually every 30 sec by a predetermined increment until the lipstick breaks.
• The test should be carried out constant temperature conditions
• As per the requirement, the lipstick should withstand a breaking load of minimum 200

6. Payoff Test

• This test gives the idea of mass release from the lipstick salve while applying
• As per the requirement, the lipstick should pass this test if pay-off is more than 0.0001gm/cm²

7. Rancidity test (Oxidative stability)

• Can be done by using hydrogen peroxide and determining its Peroxide Value
• As per the standard requirement, the rancidity should not be more than 10 (peroxide number)

8. Drop point test

• Indicates the temperature of transition from the solid or semi-solid state to the liquid state
• The Ubbelohde method is used

9. Test for penetrability

• Carried out using a penetrometer
• A needle of specific dimension is allowed to penetrate the lipstick and the depth of penetration is noted

10. Stability testing

• The stability is determined by accelerated stability testing
• Lipstick is kept at various temperatures and assessed for surface defects, perfume, colour and application characteristics
• Ageing stability is determined by storing the lipsticks in an oven at 40^oC and periodically checking the application characteristics, crystallization and oil bleeding and comparing with a fresh sample

11. Microbiological tests

• Microbiological tests such as total viable count (TVC), testing for gram-negative and gram positive pathogens

12. Presence of Heavy Metals

• The average user applies lipstick 2.3 times daily and ingests around 24 milligrams each day, so the lipstick should be free of heavy toxic metals, or within the limits
• Lipstick generally contains lead, chromium, cadmium, arsenic and many more toxic metals, which are carcinogenic in nature and may cause serious illness
• As per the standard requirement, lead and arsenic should not be more than 20 ppm and 2 ppm, respectively.

13. Sensory testing

• Are carried out by clinical research organization (CRO) with over 150 volunteers to determine the effects, perception and overall acceptability of the various lipsticks after regular use at home
• The subjects will wear the given sample of lipstick once a day for seven days.
• The following attributes will be judged by the volunteers:

Evaluation tests?

1. Improvement in appearance of lips after application. (Radiance, lustre)
2. Does your lipstick spread beyond lip edges after application?
3. Moisturizing effects of lipstick after application
4. Improvement in texture (cracking or chapping) of lips after application
5. Improvement in softness and smoothness of lips after application
6. Application of lipstick and wearable period, approx. >4 hours
7. Fragrance of lipstick after application
8. Rate as per convenience and easy use of packing of lipstick
9. Overall quality of lipstick

Summary

1. Lipstick may be defined as dispersion of the colouring matter in a base consisting of a suitable blend of oils, fats and waxes with suitable perfumes and flavors, moulded in form of sticks to impart attractive gloss and colour, when applied on lips
2. There are three main types of raw materials used in lip products: oils, waxes and colours

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